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Both brain size and IQ are falling in modern humans, coinciding with a big increase in mental illness.

What we eat is to blame, says Professor Michael Crawford, author of a new book ‘The Shrinking Brain’ and Sir David Attenborough is convinced he is right.

The Falling IQ

IQ scores have also been steadily falling for the past few decades. Norwegian researchers, headed by Ole Rogeberg, a senior research fellow at the Ragnar Frisch Center for Economic Research in Norway, analysed the IQ scores of Norwegian men born between 1962 and 1991 and found that scores steadily decreased among those born after 1975 (1). “Similar studies in Denmark, Britain, France, the Netherlands, Finland and Estonia have demonstrated a similar downward trend in IQ scores” says Rogeberg. “The decline is due to environmental factors,” 

This coincides with a change in Western diet away from fat, towards carbohydrates and sugar, based on the mistaken belief that it was fat, not sugar, that was causing heart disease and that we should all eat a low-fat diet. Since then, our IQ scores have been dropping by about 7 per cent per generation. 

“We are heading for an idiocracy” says Professor Crawford who is Director of the Institute of Brain Chemistry and Human Nutrition. Currently one in five of the world’s children and adolescents have a mental health condition (2).’  If this trend continues, by 2080 he predicts that more than a third of the world’s population will have a mental disability.

The World Health Organisation report says ‘there has been a 13% rise in mental health conditions. One in eight now suffers from mental illness. The incidence of depression is through the roof. Last year in the UK there were over 100 million prescriptions for antidepressants. 

Crawford is convinced it is the modern-day diet that is causing us to dumb down. “Our genome is adapted to eating the wild foods we ate during our species’ evolution. Today’s diet bears no resemblance to this.”

Key nutrients from land & sea

In his book, The Shrinking Brain, he says “Our ancestors evolved a unique 1,600cc brain evolving from our ancestral 350cc brain of the chimpanzee, despite our genome only differing by 1.5% (3). This could only have happened by providing brain-specific building nutrients from land and sea. There is incontrovertible evidence of early Homo sapiens exploiting the marine food web in coastal Africa.” In other words, we were the waterside ape who became smart, with bigger brains, by eating mussels, oysters, crabs and fish. 

Professor Crawford discovered, in 1971, that the brains of all mammals are rich in omega-3 DHA. Their brain size varied according to their dietary supply of DHA found in seafood. A dolphin, for example, has a 1,700cc brain, slightly larger than ours, while a lion has a 320cc brain about that of a chimpanzee. “The mix of wildland and aquatic foods powered by the encephalization of the brain from the 340cc of the chimp to the 1,500-1,700 of cro-magnon. DHA is not only involved in signalling but it stimulates gene expression in the brain so the rich aquatic food sources constantly, every day, would have powered the increase in brain size and function.” says Crawford.

“Today’s diet contains less than a tenth of the omega-3 fats that our ancestors ate and this is having dire consequences on mental health. Increased rates of depression, autism, ADHD and dementia are all strongly linked to lack of seafood. Increased intake from eating fish or supplementing omega-3 fish oils reduces dementia risk by 20 per cent (4). While a plant-based diet has many benefits, those who eat no fish, are especially vulnerable and must supplement omega-3 DHA, derived from algae. The only way to be sure you have enough is to get a blood test to specifically test your levels.” Says our CEO and founder Patrick Holford.  

This is why we have just launched a simple ‘do it at home’ pin-prick test that can give you a clear indication of your Omega-3 levels, which done alongside our Cognitive Function Test, can help identify what’s driving future risk and show you how to dementia-proof your diet and lifestyle. 

Canadian neuroscientist and brain expert Professor Stephen Cunnane at the University of Sherbrook in Canada agrees “A shore-based diet, i.e., fish, molluscs, crustaceans, frogs, bird’s eggs and aquatic plants, provides the richest known dietary sources of brain selective nutrients.” says Cunnane. “Change in diet away from marine foods is the likely explanation for this decrease in brain size.”  

Sir David Attenborough, a supporter of the waterside ape theory, agrees “Gathering molluscs is far easier than chasing elephants and wildebeests across the savannah.” 

Children & omega-3

Today, under 5 per cent of children achieve the basic requirement for omega-3 from seafood (5).

Professor Michael Crawford, who is a visiting professor at Imperial College’s Chelsea & Westminster campus and on our Scientific Advisory Board, was part of the team that has recently established that, if a pregnant woman lacks omega-3 DHA she produces a substitute fat, oleic acid, to fill the baby’s brain. But it doesn’t work. Levels of oleic acid in a pregnant woman’s blood predicted preterm birth which carries the highest risk of developmental brain problems and mental deficits in their offspring, as well as a risk of learning and cognitive disabilities. Low omega-3 and B vitamins in mothers increase risk for lower IQ, learning and emotional problems in children (6).

A new study shows that the higher the omega-3 index and DHA, the greater both the brain size and the cognition of older people (7). Brain size predicts cognitive abilities, which is why we have started offering these vital tests – which are both easy and affordable to do at home.

Brain size is worked out from skull capacity. Homo sapiens skulls dating back to 29,000 years ago had a brain capacity of 1,660cc. By 10,000 years ago it was around 1,500cc or 1.5 kilograms. The average brain size today is a fifth smaller, at 1,336cc. Brain size may have started to shrink from 10,000 years ago, coinciding with mankind developing more land-based agriculture and eating less marine food along rivers and coasts.

 So we are inviting you to join our ‘citizen science’ study to track the impact of diet and Omega-3 on cognitive function over time.

Our brains and mental health are suffering as a result of our dietary changes.

So if you are concerned about your levels of Omega-3 and how it might be impacting your brain, body and life – you can now test your levels with our Omega-3 hometest kit here, which is offered alongside the free Cognitive Function Test, which assesses how well your diet is supporting your brain health.

Thank you for reading!
Food for the Brain is a non-for-profit educational and research charity that offers a free Cognitive Function Test and assesses your Dementia Risk Index to be able to advise you on how to dementia-proof your diet and lifestyle.

By completing the Cognitive Function Test you are joining our grassroots research initiative to find out what really works for preventing cognitive decline. We share our ongoing research results with you to help you make brain-friendly choices.

Please support our research by becoming a Friend of Food for the Brain.

Supporting Research

IQ FALLING

Bratsberg B, Rogeberg O. Flynn effect and its reversal are both environmentally caused. Proc Natl Acad Sci U S A. 2018 Jun 26;115(26):6674-6678. doi: 10.1073/pnas.1718793115. Epub 2018 Jun 11. PMID: 29891660; PMCID: PMC6042097.

DECREASE IN BRAIN SIZE

Cunnane SC, Crawford MA. Energetic and nutritional constraints on infant brain development: implications for brain expansion during human evolution. J Hum Evol. 2014 Dec;77:88-98. doi: 10.1016/j.jhevol.2014.05.001. Epub 2014 Jun 11. PMID: 24928072.

MENTAL HEALTH RISING

OMEGA-3 PREDICTS COGNITIVE PROBLEMS IN CHILDREN

Montgomery P, Burton JR, Sewell RP, Spreckelsen TF, Richardson AJ. Low blood long chain omega-3 fatty acids in UK children are associated with poor cognitive performance and behavior: a cross-sectional analysis from the DOLAB study. PLoS One. 2013 Jun 24;8(6):e66697. doi: 10.1371/journal.pone.0066697.

OMEGA-3 PREDICTS RISK FOR DEMENTIA AND COGNITIVE DECLINE

Wei BZ, Li L, Dong CW, Tan CC; Alzheimer’s Disease Neuroimaging Initiative; Xu W. The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers. Am J Clin Nutr. 2023 Jun;117(6):1096-1109. doi: 10.1016/j.ajcnut.2023.04.001. Epub 2023 Apr 5. PMID: 37028557; PMCID: PMC10447496.

OMEGA-3 LEVELS PREDICT BRAIN SIZE IN OLDER PEOPLE

Loong, S.; Barnes, S.; Gatto, N.M.; Chowdhury, S.; Lee, G.J. Omega-3 Fatty Acids, Cognition, and Brain Volume in Older Adults. Brain Sci.2023,13,1278. https://doi.org/ 10.3390/brainsci13091278 

References

¹ Bratsberg B, Rogeberg O. Flynn effect and its reversal are both environmentally caused. Proc Natl Acad Sci U S A. 2018 Jun 26;115(26):6674-6678. doi: 10.1073/pnas.1718793115. Epub 2018 Jun 11. PMID: 29891660; PMCID: PMC6042097.

² https://www.who.int/publications/i/item/9789240049338

³ Cunnane SC, Crawford MA. Energetic and nutritional constraints on infant brain development: implications for brain expansion during human evolution. J Hum Evol. 2014 Dec;77:88-98. doi: 10.1016/j.jhevol.2014.05.001. Epub 2014 Jun 11. PMID: 24928072.

⁴ Wei BZ, Li L, Dong CW, Tan CC; Alzheimer’s Disease Neuroimaging Initiative; Xu W. The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers. Am J Clin Nutr. 2023 Jun;117(6):1096-1109. doi: 10.1016/j.ajcnut.2023.04.001. Epub 2023 Apr 5. PMID: 37028557; PMCID: PMC10447496.

⁵ Kranz, S.; Jones, N.R.V.; Monsivais, P. Intake Levels of Fish in the UK Paediatric Population. Nutrients 2017, 9, 392. https://doi.org/10.3390/nu9040392

⁶ Montgomery P, Burton JR, Sewell RP, Spreckelsen TF, Richardson AJ. Low blood long chain omega-3 fatty acids in UK children are associated with poor cognitive performance and behavior: a cross-sectional analysis from the DOLAB study. PLoS One. 2013 Jun 24;8(6):e66697. doi: 10.1371/journal.pone.0066697. Erratum in: PLoS One. 2013;8(9); see also Veena SR, Krishnaveni GV, Srinivasan K, Wills AK, Muthayya S, Kurpad AV, Yajnik CS, Fall CH. Higher maternal plasma folate but not vitamin B-12 concentrations during pregnancy are associated with better cognitive function scores in 9- to 10- year-old children in South India. J Nutr. 2010 May;140(5):1014-22. doi: 10.3945/jn.109.118075. Epub 2010 Mar 24. PMID: 20335637; PMCID: PMC3672847; see also McNulty H, Rollins M, Cassidy T, Caffrey A, Marshall B, Dornan J, McLaughlin M, McNulty BA, Ward M, Strain JJ, Molloy AM, Lees-Murdock DJ, Walsh CP, Pentieva K. Effect of continued folic acid supplementation beyond the first trimester of pregnancy on cognitive performance in the child: a follow-up study from a randomized controlled trial (FASSTT Offspring Trial). BMC Med. 2019 Oct 31;17(1):196. doi: 10.1186/s12916-019-1432-4. PMID: 31672132; PMCID: PMC6823954.

⁷ Loong, S.; Barnes, S.; Gatto, N.M.; Chowdhury, S.; Lee, G.J. Omega-3 Fatty Acids, Cognition, and Brain Volume in Older Adults. Brain Sci.2023,13,1278. https://doi.org/ 10.3390/brainsci13091278 

Developing dementia is the second biggest health fear, after cancer. But what can you do about it? 

The conventional view is that genes play a big part and that factors under our control, including diet, lifestyle and health status, account for up to 40% of risk and therefore up to 40% of dementia cases could be prevented or delayed. Genes actually account for less than 1% of Alzheimer’s cases. But a new study from the UK BioBank, following 344,000 people over 15 years, estimates that “up to 73% of cases could be prevented” by targeting risk factors largely under our control. 

The authors of the study, published in the Nature Human Behaviour journal (1), investigated 210 modifiable risk factors. They found that increased hand grip strength (a good reflection of physical strength), increasing leisure or social activities or time spent in sports clubs or gyms, spending less time watching TV or on a computer, having better dental health, drinking more water, not dozing off in the day and sleeping between 7 to 9 hours a night, not smoking or being exposed to smoke and having better lung function were all associated with less risk of Alzheimer’s. Being unemployed, having a low income, having diabetes, high blood pressure or having had a stroke or brain injury all increased risk. Inheriting the so-called ‘Alzheimer’s gene’, ApoE4, didn’t make any significant difference to overall risk.

However, even this figure of 73% may be an underestimate as this study excluded blood test measures. “We have under-estimated the power of prevention,” says Professor David Smith from the University of Oxford, one of the study authors. “Even this figure of up to 73% of cases preventable could be higher if a person’s omega-3 and B vitamin status, measured by a blood test for homocysteine that any GP can do, were taken into account.”

While the BioBank study didn’t include blood test measures of either homocysteine or omega-3, scientists at the US National Institutes of Health have attributed 22% of the risk of Alzheimer’s to raised blood homocysteine and 22% to a lack of omega-3 (2). “These have been shown to predict risk but were beyond the scope of this study.” confirmed the study author, Professor Jin-Tai Yu from Shanghai’s Fudan University. “Homocysteine-lowering treatment with B vitamins, especially B12, is one of the most promising interventions for dementia prevention.” 

The Impact of B Vitamins & Omega-3

Professor Smith’s group at Oxford University tested the effects of giving B vitamins (B6, B12, folate) versus placebo to those with pre-dementia and found that the 10p a day supplements halved the rate of brain shrinkage in one year and virtually stopped further memory loss (3). “The greatest effect we found in our trial was in those in the top third of DHA blood levels (an omega-3 found in fish or fish oil supplements). Those with high DHA reduced their rate of brain shrinkage by 73%, down to the level normally seen in older people with loss of cognitive function. They also had virtually no further memory loss and almost a third ended the trial with no clinical dementia rating at all.”

The benefit of omega-3 was also confirmed in a major study this year of over 100,000 people, finding that increased omega-3 cut the risk of dementia or cognitive decline by around 20%. An increase in intake of omega-3 DHA of 200 mg decreased risk by almost a fifth (4). 

And here at Food for the Brain, we take prevention seriously.

Alzheimer’s is preventable, but not curable

We developed the free online Cognitive Function Test,  which includes a Dementia Risk Index questionnaire assessing your diet, omega-3 and B vitamin status, and lifestyle and an optional home-test kit for pinprick blood tests that will be available soon.

“Over 400,000 people have taken our validated Cognitive Function Test, which not only shows a person their cognitive status right now but also their future risk based on our Dementia Risk Index questionnaire, the factors driving future risk and what they can easily do right now to lower it. If all modifiable risk factors are taken into account, including B vitamins and omega-3, it is highly likely a person could reduce risk by over 80%.” says our CEO, Patrick Holford.

“The government has pledged £160 million a year for dementia prevention research but we are not seeing any of this going into easy prevention wins. Most seem to be fueling drug research for an apparent ‘cure’.

Alzheimer’s is preventable, but not curable. You cannot reverse holes in the brain. With over 200,000 people diagnosed every year with dementia, if prevention were taken seriously we could halve the number of people developing this terrible, but preventable disease.”

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Thank you for reading!
Food for the Brain is a non-for-profit educational and research charity that offers a free Cognitive Function Test and assesses your Dementia Risk Index to be able to advise you on how to dementia-proof your diet and lifestyle.

By completing the Cognitive Function Test you are joining our grassroots research initiative to find out what really works for preventing cognitive decline. We share our ongoing research results with you to help you make brain-friendly choices.

Please support our research by becoming a Friend of Food for the Brain.

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References

¹ Zhang, Y., et al. Nature Human Behaviour. 2023 7, 1185–1195

² Beydoun MA., et al. BMC Public Health. 2014 Jun 24;14:643.

 Jernerén F., et al. Am J Clin Nutr. 2015 Jul;102(1):215-21.

³ Oulhaj A., et al. J Alzheimers Dis. 2016;50(2):547-57.

⁴ Wei B., et al. Am J Clin Nutr 2023 Jun;117(6):1096-1109. 

Last month’s newspaper headlines pitched the new anti-amyloid Alzheimer’s drug as a ‘turning point’. The pitch has a lot in common with the statin story.

Last month’s newspaper headlines pitched the new anti-amyloid Alzheimer’s drug as a ‘turning point’. (Read our response here) The pitch has a lot in common with the statin story.

Is high cholesterol the cause of heart disease? No. 

Do statins lower it? Yes.

Are amyloid deposits the cause of cognitive decline? No. 

Do anti-amyloid drugs lower it? Yes.

No doubt there will be a blood test soon for amyloid, just like a blood test for cholesterol, the effect of which pushed millions into taking statins.

Both statins, given to people with very high cholesterol, and anti-amyloid drugs, given to people with very high amyloid levels, do have marginal benefit but not enough to establish causation. In the case of the new Alzheimer’s drug, the benefit is considerably less than half that shown by the combination of B vitamins and omega-3. 

But, even more than statins, they come with a high risk of quite serious adverse effects – over a third in the recent trial got brain bleeding or swelling and three died. Also, the whole brain shrinkage accelerated by twenty percent compared to placebo, a fact not reported in any newspaper. Any vitamin showing such adverse effects would be immediately banned.

But the important question is: what’s causing these diseases, be it cognitive decline or heart disease? To the extent that cholesterol or amyloid is relevant, what makes them go up? Cholesterol gets damaged by sugar and oxidants and is protected by antioxidants such as vitamin C and a low-carb diet. Brain cells get damaged by homocysteine and are protected by B vitamins and omega-3.

Mind the gap 

Also, in those with cognitive decline, there’s an energy deficit in brain cells. Ironically, they can’t get the glucose they need due to ‘insulin resistance’ which is driven by eating too much sugar and ultra-processed carbs. So, the effect of too much sugar is to starve the brain of fuel which then leads to mental tiredness and cognitive decline. 

There is a way around this – and that is to give the brain an alternative fuel – ketones. 

Ketones can either be supplied as ketone salts or esters, both of which taste disgusting or made from a type of fat – principally C8 oil, which is a medium-chain triglyceride. About 7 percent of coconut oil is C8. Studies giving people with cognitive decline a C8-rich MCT oil have shown clear improvements in cognition by increasing the brain’s energy supply and production. Ripping out amyloid deposits isn’t going to fill this energy gap. Eating less carbs, reversing diabetes, which is a big risk factor for dementia, and having C8 oil will. Our podcast with Professor Stephen Cunnane, who heads the Brain Research Team at Sherbrooke University in Sherbrooke, Quebec, Canada and holds the clinical research chair in ketotherapeutics and on the Food for the Brain Scientific Advisory Board, discusses this area with Patrick Holford – listen to the podcast here.

Also, in those with cognitive decline, there’s an energy deficit in brain cells. Ironically, they can’t get the glucose they need due to ‘insulin resistance’ which is driven by eating too much sugar and ultra-processed carbs. So, the effect of too much sugar is to starve the brain of fuel which then leads to mental tiredness and cognitive decline. 

An increase in amyloid in the brain is really a consequence of the disease, not the cause. It’s part of an inflammatory reaction, much like the nodules in joints that occur from inflammation resulting in arthritis. Should you cut out the nodules or reduce inflammation? Do you eliminate the root cause or target the consequences? Inflammation is both a function of a bad diet high in ultra-processed and fried food, smoking, lack of antioxidants, omega-3 fats and vitamin C to name a few key nutrients. Having an active lifestyle is also important.

The same story exists with all major diseases. Cancer cells thrive on sugar. Do you starve them and in the process protect healthy cells, or cut or drug them out?

The big difference in approach – treat the cause or the consequences – is money.  You can’t patent nutrients, but you can patent drugs that stop you from making cholesterol or amyloid. More than $1 billion has been spent on the anti-amyloid approach and the push isn’t going to stop. Pharma needs a return on their investment. This latest drug treatment, according to the Financial Times, will be sold for $26,000 a year. Taking B vitamins, eating fish and/or supplementing omega-3, which has shown more clinical benefit and reduced the rate of brain shrinkage by over 70% with no side-effects – actually side-benefits – might cost £100 a year. Which would you choose?

Food for the Brain is a non-for-profit educational and research charity that offers a free Cognitive Function Test and assesses your Dementia Risk Index to be able to advise you on how to dementia-proof your diet and lifestyle.

By completing the Cognitive Function Test you are joining our grassroots research initiative to find out what really works for preventing cognitive decline. We share our ongoing research results with you to help you make brain-friendly choices.

Please support our research by becoming a Friend of Food for the Brain.

Friday’s Guardian article on ‘I refuse to get old’ about how readers strive to keep dementia at bay, on the face of it, seems like a good message. Most cases given focussing on people increasing physical and mental activity, as an active lifestyle is certainly a positive step towards prevention. But these two prevention steps reduce risk by less than B vitamins, omega-3 and reducing sugar and carbs.

The first error is the extent to which dementia can be prevented. The article says by 40%, which is based on the inaccurate Lancet Commission’s Livingston report which, despite being sent all the evidence, doesn’t even mention B vitamins and homocysteine, which is the single most important prevention step. There’s also only one mention of omega-3 from a redundant study so this risk factor is also ignored to arrive at the ‘40% preventable’ figure.

80% of dementia cases could be prevented, not 40%

The latest assessment of how much can be prevented, based on UK Biobank data is “47%–73% of dementia cases could be prevented.” This was published last week in Nature and even this is an underestimate because, while including B vitamins, it excludes the impact of omega-3 and seafood. If that modifiable risk factor were included it is likely that around 80% of dementia cases could be prevented. This would mean that the Guardian is halving the impact of prevention.

The next error is no-one quoted in the article mentions diet, let alone B vitamins or omega-3, except for Professor David Smith. He rightly says: ‘The large leap forward in what we know about preventability has informed his own retirement lifestyle: he walks for half an hour a day, spends at least 15 minutes on an exercise bike, drinks alcohol sparingly, and follows a Mediterranean diet.

Having led a clinical trial into the benefits of B vitamins in people with mild cognitive impairment – a memory-loss condition that increases the chance of those who have it developing dementia – Smith takes 500mcg of vitamin B12 daily and fish oil with Omega 3. Nutrition, he believes, is not given enough prominence when we talk about prevention.’

When we calculated the attributable risk for each risk factor for our online Dementia Risk Index questionnaire each domain scores as follows, adding up to 100%:

B Vitamins           18%

Brain Fats             17%

Glycemic Load     15%

Active Body          15%

Active Mind          10% 

Sleep & Calm       10%

Antioxidants         10%

Gut  Health          5%

So, the biggest impact you can have on your risk is to supplement B vitamins, especially B12, and omega-3 fish oils, as David Smith does. But the Guardian article then downplays the role of supplements with this statement ‘Alzheimer’s Research UK does not recommend any supplements in particular, but says “there is no harm in people taking a supplement to reduce the risk of deficiency”.

B12 Reference Ranges are wrong

This is not only wrong because brain shrinkage occurs well within the ‘normal’ range of either B12 dietary intake or blood tests, but also ARUK, who largely promotes drug-based solutions, happened to know what they are saying is wrong because they funded, back in 2010, a top level, randomised placebo controlled trial on B vitamins that, virtually stopped cognitive decline and reduced brain shrinkage by 52% – in the group with higher omega 3 , by 73% – that is the most effective disease modifying treatment to date! In fact, David Smith and I have written to ARUK to stop making this inaccurate statement. Here’s why it’s wrong:

The reason so many people are low in B12 is less to do with dietary intake and more due to malabsorption which often becomes worse with age, due to lack of stomach acid secretions which are needed to absorb B12. So relying only of analysing what someone eats (meat, fish, eggs, dairy being the only sources of B12) doesn’t prove sufficiency. Note that David Smith says he supplements 500mcg of B12 daily, while the basic ‘Nutrient Reference Value’ (NRV) that you’ll see on the back of a vitamin supplement is 2.5mcg. So, why does he take two hundred times this amount? Because you cannot rely on your dietary intake to confirm sufficiency. Also, there is growing body of evidence from well designed studies showing that supplements giving nutrients at levels beyond the basic ‘recommended intakes’ delay, eliminate or ameliorate symptoms of dementia.

So, what about blood tests? One UK study reports that 2 in five people over 61 have insufficient levels of B12 to prevent accelerated brain shrinkage. Serum B12 is the ‘standard’ test used by doctors. The UK reference range of above 180pg/ml being sufficient (and the US lower level of 200pg/ml) is out of date and in need of revision. In Europe and Japan anything below 500pg/ml is considered deficient. Accelerated brain shrinkage due to a lack of B12 does happen with B12 levels below 500pg/ml.

In conclusion, while it is good to recommend a physically and intellectually lifestyle, ignoring the need to supplement B vitamins, especially B12, eat fish and supplement omega-3, and cut your intake of carbs and sugar, is not doing anyone any favours.

Take the free test here to work out which simple steps will most reduce your risk.

Food for the Brain is a non-for-profit educational and research charity that offers a free Cognitive Function Test and assesses your Dementia Risk Index to be able to advise you on how to dementia-proof your diet and lifestyle.

By completing the Cognitive Function Test you are joining our grassroots research initiative to find out what really works for preventing cognitive decline. We share our ongoing research results with you to help you make brain-friendly choices.

Please support our research by becoming a Friend of Food for the Brain.

Don’t be fooled by the rhetoric promoting the new Alzheimer’s anti-amyloid drug. The results – increased brain shrinkage, a third getting brain bleeding or swelling and questionable clinically meaningful benefit – are not good.

However, reading this week’s headlines claiming a ‘turning point’ in the fight against Alzheimer’s you’d be mistaken in thinking something new has occurred since Eli Lilly’s press release regarding their new drug, donanemab, a month ago. What stimulated this week’s front pages was publication of the actual study in the Journal of the American Medical Association [1] giving more details of the results. This was reported positively in every major newspaper. Yet not one reported the fact that the drug treatment accelerated the rate of brain shrinkage by over 20% compared to placebo. This is clearly stated in the paper as “At 76 weeks, MRI [scans] showed a greater decrease in whole brain volume”.

This is consistent with a meta-analysis of all anti-amyloid treatments including donanemab, in the journal Neurology [2] earlier this year, which concluded that “Mild cognitively impaired participants treated with anti-amyloid drugs were projected to have a material regression toward brain volumes typical of Alzheimer dementia approximately 8 months earlier than if they were untreated.”

In stark contrast, treatment with homocysteine-lowering B vitamins, given to those with sufficient omega-3, ‘the rate of atrophy was significantly slowed by circa 70%’.[3] B vitamins and omega-3 are but two out of eight established prevention steps you can take yourself.

Alzheimer’s is characterised by brain shrinkage, and particularly in the central ‘hippocampus’ area of the brain. The new drug treatment was not associated with shrinkage of the hippocampus, just the whole brain. In fact, there was a very small reduction of about one per cent in shrinkage in this area of the brain compared to the placebo. In the B vitamin study there was an 80% reduction in shrinkage in the medial temporal lobe. While it is theoretically possible that, having selected people with lots of plaques, then targeting them with an aggressive drug, the brain may have shrunk as part of the process of amyloid destruction, this is not yet known and therefore this increased brain shrinkage is worrying

The other main measure of Alzheimer’s and dementia, made by a health professional, include interviewing the patient’s carer or partner – thus potentially subject to ‘hopeful’ bias – is the Clinical Dementia Rating (CDR).

The new drug treatment results do show a statistically significant improvement, showing just over half a point  (0.67) less worsening, compared to placebo, on the 18 point CDR scale. But is this small change meaningful? A study in the Lancet suggests that minimum changes of 0.98 in mild cognitive impairment and 1.63 in mild Alzheimer’s disease are meaningful. [4] This study was on those with early Alzheimer’s.

In contrast, a trial giving omega-3 fish oils to those with adequate B vitamin status, showed three times this beneficial clinical effect [5]. In another, giving homocysteine lowering B vitamins to those with adequate omega-3, almost two thirds of the trial participants ended the trial with an overall Clinical Dementia Rating of zero [6]. This means they were no longer diagnostically labelled as having cognitive impairment. In other words, not less worse, but actually better. 

Serious adverse effects including deaths

More details in the recent donanemab paper were given on the adverse effects and trial deaths. ‘Treatment-emergent adverse events’ were reported by 759 of 853 participants (89%) receiving donanemab’ and ‘Either amyloid-related imaging abnormalities of edema/effusion [swelling] or microhaemorrhages [bleeding] occurred in 314 participants (37%) receiving donanemab’. Also, in the donanemab group, ‘3 participants with serious amyloid-related imaging abnormalities subsequently died.’ This means that more than a third had brain bleeding or swelling and 1 in 287 died. This compares to no adverse events in the B vitamin and omega-3 trials, or other prevention approaches. If any nutritional supplement had anything like these adverse effects it would be banned, not licenced.

According to the Financial Times, this new treatment will cost $26,000 a year (in addition to medical costs including numerous scans). In the UK this would be paid by the taxpayer. In contrast, taking homocysteine-lowering B vitamins, eating fish and/or having fish oil supplements would cost perhaps 20p or cents a day.

So, the question is would you rather take a treatment that markedly slows both whole brain and medial temporal lobe shrinkage than a treatment that is associated with a greater loss of brain volume, a high risk of adverse effects and costs.

The big push is now on to get approval of the UK’s NICE  (National Institute for Health & Care Excellence) and the drug licensed in Europe. NICE have previously refused to consider the evidence for homocysteine-lowering B vitamins and omega-3, which is now overwhelmingly positive, when both these nutrients are combined.

That is why we, at Food for the Brain, aim to make sure as many people as possible know that the real ‘turning point’ for Alzheimer’s is prevention through diet, nutrition and lifestyle improvements, not expensive drugs with dangerous side-effects.

Please take the Cognitive Function Test yourself at foodforthebrain.org, and encourage all you know to do the same. We appreciate your support by becoming a Friend at foodforthebrain.org/friend. 

REFERENCES

1. Simms J., et al JAMA July 17, 2023.

2. Alves, F., et al Neurology 2023 May 16;100(20):e2114-e2124. 

3. Jernerén F., et al. Am J Clin Nutr. 2015 Jul;102(1):215-21.

4. Liu KY., et al Lancet Psychiatry 2021;8:-6.

5. Jernerén F., et al J Alzheimers Dis. 2019;69(1):189-197. doi: 10.3233/JAD-181148. PMID: 30958356

6. de Jager C et al Int. J. Geriatr. Psychiatry 27:592–600 2012

Autism is one disease where there is a very high ‘inherited’ component.

In studies with genetically identical twins, if one twin has it, the odds of another having a diagnosis is about 60%. But it’s not in the ‘in the genes’ since we share the same ‘environment’ as our siblings.

Perhaps the more interesting question is why the number of children diagnosed with Attention-deficit /hyperactivity disorder (ADHD), autism and other neurodevelopmental disorders classifying them as ‘neurodivergent’, has rocketed in both the UK and US.

One in six children is ‘neurodivergent’ as autism numbers quadruple.

UK figures (see here) which show that just under 1.5 million pupils in England have special educational needs which is one in six children. Autism is the biggest part of this, has been steadily rising in both the Uk and US.

“Now, one in six children in the US are classified as neurodivergent and one in 36 as autistic – a fourfold increase in 20 years.” says pediatric Professor Alessio Fasano from Massachusetts General Hospital for Children, Harvard Medical School.  

—

All down to our increased awareness & better diagnosis?

According to Dr Rona Tutt OBE, past president of the UK’s National Association of Head Teachers “There has been a dramatic increase in the number of people being diagnosed with ASD. Although some of this is due to a broader definition of autism as well as better diagnosis, it raises the question of whether it may also be the result of environmental changes, which have also been dramatic.” 

Some UK schools are reporting as many as one in four children having problems.

Have our genes changed in the past few decades?

Since the genes cannot have changed this rapidly, the increase points to the influence of environmental factors of which there are many candidates.

The main suspects are:

Gut problems
Wheat, milk and sugar
Vaccines
Environmental anti-nutrients and toxins
Social media overuse and social issues
Maternal nutrition and brain formation essential fats 

—

The gut’s role

World-renowned pediatric gastroenterologist, and research scientist Professor Alessio Fasano, MD, directs the Center for Celiac Research and Treatment at Massachusetts General for Children thinks something is going wrong in the gut, with many ASD children reporting gut problems including diarrhoea, constipation, belching and excessive flatulence and ‘dysbiosis’ – abnormal patterns of gut bacteria. In some children, wheat and milk may contribute to these symptoms. His research finds that neurodivergent children show high levels of ‘zonulin’, a family of proteins that regulate the barrier between intestinal cells in the digestive tract that can lead to “leaky gut.” ASD children are often found to have opioid-like wheat and milk proteins in their urine, making these foods especially ‘addictive’.

—

Prenatal nutrition?

Professor Michael Crawford, who heads the Institute of Brain Chemistry and Human Nutrition at the Chelsea & Westminster Hospital says “We can predict which babies are going to have developmental problems from the fats in the mother’s blood. When omega-3 levels are low, the mother produces a non-functional ‘brain fat substitute’ to build their baby’s brain during pregnancy, high levels of which predict problems. The brain is 50% fat, and omega-3 DHA should make up most of the structural fat in brain cells.” Less than 5 per cent of children in the UK achieve the basic dietary recommendations for omega-3 and fish.

—

Methylation & B vitamins

Vitamins may help. ‘A high level of homocysteine, a marker for B vitamin deficiency, predicts ASD and studies have shown that giving homocysteine-lowering vitamin B6, B12 and folate help reduce symptoms.” says Patrick Holford from the Food for the Brain Foundation, which is hosting the masterclass. “Vitamin A improves eye coordination and vision, helping those with autism who don’t look you in the eye and have visual problems.”

A 12-month randomised controlled trial giving omega-3, vitamins, digestive enzymes and a healthy gluten-free, casein-free diet showed major improvement in both autistic symptoms and raising IQ.

Nutrition and functional medicine therapist Anne Pemberton, who specialises in helping those with ASD, is spoke at the Autism Masterclass reports considerable success, not just by improving nutrition but by addressing the psychological and social circumstances of neurodivergent children. “It is critical to work with both mother and child, and not only address critical nutritional issues, stress triggers including early life traumas, and suppressed emotions as a result of their condition and conditioning, and to help them develop a sense of self and mindset. I have seen hundreds of children and adults who usually have major improvements. Peter, age 8, is a case in point. He was diagnosed with ASD and classified as needing special education. 15 months later he’s no longer even classified as ASD.”

So, as you can see, there are many layers to Autism and Neurodivergence.

For more information you can:

Get instant access to our Autism Masterclass to learn from the expert
Find out more about our Smart Kids & Teens Programme here to learn about the program, conference and more!

Failure of yet another anti-amyloid drug is hailed as ‘the beginning of the end for Alzheimer’s’, according to the Times headline today. It certainly was the end for two, possibly three volunteers given the experimental drug, according to the BBC [1] .

Like other anti-amyloid drugs, the level of significant adverse effects was unacceptably high. According to the Eli Lilly’s press release [2] (no trial has been published) one quarter (24%) of those on the drug developed brain swelling and 24% brain bleeding. It is these adverse effects that can cause death. I’m not quite sure how the BBC conclude only ‘1.6% developed dangerous brain swelling’. Perhaps they meant the level of swelling that could be fatal? But brain swelling and bleeding is not a good idea in elderly people with pre-dementia. Apart from anything else this means they’d need frequent and expensive brain scans to check whether or not this was occurring with each monthly treatment.

The press release inflated the apparent benefit in the usual way saying ‘29% less reduction, compared to placebo’ on the main measure of Clinical Dementia Rating , thus showing the relative, not absolute effect on cognitive assessment. What it actually means is that those on the placebo degenerated from a clinical perspective and those on the drug degenerated a bit less so.

The measure in question, Clinical Dementia Rating (Sum of Boxes), is a questionnaire, administered by a health professional who asks the patient’s partner or carer to rate their memory and 6 aspects of their general functional ability as being normal, questionable, mild, moderate or severe. Depending on the carer’s assessment each question adds either zero (if normal), 0.5, 1, 2 or 3 to the ‘Sum of Boxes’ score, which can therefore range from zero (nothing wrong) to 18 (severe impairment in everything). This is balanced by an interview with the participant who answers questions related to each of the domains/aspects of functional ability, and the doctor or rater scores the CDR taking both the subjective and objective evidence into account. The previous anti-amyloid drug trial, which reported less than half a point (0.45) difference, has been criticised for potential ‘unblinding’. This means that the carer or partner, when asked about how they thought the ‘patient’ was doing, might be biased to provide a more optimistic assessment because they knew they were on the drug from the adverse effects and thus hoped there was some improvement.

So, what happened in this trial? Those on the placebo got 2.4 points worse over 18 months and those on the drug treatment got 1.7 points worse. That’s relatively 29% less worse, but the absolute improvement is the difference, namely 0.49 points, similar to the previous ant-amyloid treatment reporting 0.45 points. So, no meaningful difference between the previous failed drug, nor the one before it which reported 0.39 points on an 18-point scale. According to a British Medical Journal editorial “minimum changes of 0.98 in mild cognitive impairment and 1.63 in mild Alzheimer’s disease are meaningful.” [3] This means that these results were clinically meaningless. All data from the drug company’s own press release.

How this hails the ‘beginning of the end’ of Alzheimer’s beggar’s belief. When compared with the effect of B vitamins or omega-3 fish oil in similar randomised controlled placebo trials [4], these results pale into insignificance, and especially the combination of the two[5]. In those with high homocysteine, given B vitamins, and with sufficient omega-3, there was 73% less brain shrinkage [6] and a third ended the trial with an overall Clinical Dementia Rating of zero [7] – i.e. no longer diagnostically labeled as having dementia. In other words, not less worse, but actually better. Why does this not get reported?

Foodforthebrain.org offers a free, validated online Cognitive Function test that includes an assessment of a person’s Dementia Risk Index with guidance on how to reduce that risk.

>> Take the Test here <<

Reference & Links

¹ https://www.bbc.co.uk/news/health-65471914

²  https://investor.lilly.com/news-releases/news-release-details/lillys-donanemab-significantly-slowed-cognitive-and-functional

³  Walsh S, Merrick R, Richard E, Nurock S, Brayne C. Lecanemab for Alzheimer’s disease. BMJ. 2022 Dec 19;379:o3010. doi: 10.1136/bmj.o3010. PMID: 36535691.

⁴  Jernerén F, Cederholm T, Refsum H, Smith AD, Turner C, Palmblad J, Eriksdotter M, Hjorth E, Faxen-Irving G, Wahlund LO, Schultzberg M, Basun H, Freund-Levi Y. Homocysteine Status Modifies the Treatment Effect of Omega-3 Fatty Acids on Cognition in a Randomized Clinical Trial in Mild to Moderate Alzheimer’s Disease: The OmegAD Study. J Alzheimers Dis. 2019;69(1):189-197. doi: 10.3233/JAD-181148. PMID: 30958356; see also Jernerén F, Elshorbagy AK, Oulhaj A, Smith SM, Refsum H, Smith AD (2015). Brain atrophy in cognitively impaired elderly: the importance of long-chain ω-3 fatty acids and B vitamin status in a randomized controlled trial. Am J Clin Nutr. 2015 Jul;102(1):215-21

⁵  Oulhaj, A et al, ‘homocysteine as a predictor of cognitive decline in Alzheimer’s Disease’, Int J Geriatric psychiatry, 25(1): 82-90 (2010)

⁶  Douaud G, Refsum H, de Jager CA, Jacoby R, Nichols TE, Smith SM, Smith AD. Preventing Alzheimer’s disease-related gray matter atrophy by B-vitamin treatment. Proc Natl Acad Sci U S A 2013; 110: 9523-8.

⁷ Oulhaj A, Jernerén F, Refsum H, Smith AD, de Jager CA. Omega-3 Fatty Acid Status Enhances the Prevention of Cognitive Decline by B Vitamins in Mild Cognitive Impairment. J Alzheimers Dis. 2016;50(2):547-57. doi: 10.3233/JAD-150777. PMID: 26757190; PMCID: PMC4927899.

In the UK progress in putting these breakthroughs into action is slow. The two leading charities, the Alzheimer’s Society and Alzheimer’s Research UK (ARUK) fail to mention the importance of homocysteine lowering B vitamins and omega-3 at all and have confirmed that they are not funding any research on their use in prevention or planning to do so. ARUK’s chief medical officer Professor Jon Schott and the Alzheimer’s Society’s associate director of research, Richard Oakley, declined to comment.

ARUK’s Brain Health Check-In, a short 13 question check list, with only one very basic question on diet, says nothing at all about B vitamins or whether or not a person supplements omega-3 fish oils despite ARUK having part-funded the Oxford University research. According to Professor Smith, who was the first Chair of their Scientific Advisory Board “ARUK part-funded our trial on B vitamins, and are aware of the results. I don’t understand why they make no mention of such an effective preventive intervention, that is taking a 10p a day B vitamin supplement if your homocysteine is high. Now we know that those who also supplement with omega-3 fish oil, or eat fish regularly, reduce their risk. These are the easiest two prevention actions anyone can take, with a significant impact on reducing the risk for dementia. Everyone needs to know this.”

“We’ve been applying to UK and EU agencies for the past 8 years to fund the obvious next trial – testing the effects of B vitamins and omega-3 combined to see if they slow, or prevent, conversion from cognitive impairment to dementia, but to no avail.” Says Professor Smith.

Neither the Alzheimer’s Society, nor ARUK are funding any vitamin or omega-3 research and spend virtually none of their annual research pot, which exceeded £37 million last year, on diet or lifestyle prevention which offer the most potential, despite these representing up to half of the risk for Alzheimer’s. Neither would confirm the percentage of their research funds that were being spent on prevention research.

UK Government have pledged to deliver ‘Dementia Moonshot’, doubling dementia research funding to £160 million to ‘fast-track the development of new treatments’, meanwhile ignoring the biggest breakthroughs in diet and lifestyle prevention. Most support is feeding failed drug research. With an estimated $50 billion [12] spent so far on amyloid drugs and research, all of which have failed to produce any clinical benefit, isn’t it time governments and Alzheimer’s charities took prevention seriously?

In contrast, the Food for the Brain Foundation are doing just that. “At Foodforthebrain.org we are testing almost 4,000 people every month on our free online Cognitive Function Test, and assessing all risk factors on a 140 question questionnaire, including the need for B vitamins and omega-3. We hope, soon, to introduce a pinprick blood test for both omega-3 and homocysteine. We don’t know why the most evidence-based, easy to action and inexpensive prevention steps are being ignored” says Holford. “Why world class scientists such as Professor David Smith’s team at Oxford University have been unable to get funding for the most essential research is shameful. Right now we know enough to cut the average person’s risk of developing Alzheimer’s by up to two thirds and the number of people developing dementia by a third if only there was the political will to do so.”

One of the reasons for complacency in the UK is the Lancet’s commissioned report on Alzheimer’s prevention chaired by Gillian Livingston, Professor of Psychiatry for Older  People, at the University College London (UCL). The report, first published in 2017, didn’t include B vitamins. Despite being sent all the evidence by Smith. The 2020 revised report still excluded this vital research, as did a follow up report specifically on supplements in 2022. “There are no trials that show that lowering homocysteine has any benefit” she told us yet she had been sent the unequivocal evidence that the B vitamins reduced brain shrinkage by up to 73%, compared to the 2% reduction of anti-amyloid drugs and the combination of omega-3 and B vitamins has lowered the Clinical Dementia Rating (CDR) in placebo controlled trials by three times that reported by the recent anti-amyloid drug, Lecanemab. (see charts below).

When asked about the recent finding of a synergistic effect of B vitamins and omega-3 she said “It sounds a good hypothesis. I hope they can get the funding for it, but raised homocysteine is not common in the wider population and drug companies can’t be expected to fund nutrition trials, so money would have to come from some government agency.”

There is one prevention study, called AppleTree, underway at University College London. It focuses on reducing risk for Alzheimer’s by eating a Mediterranean style diet and lifestyle advice, including encouraging smokers to quit, which is a known risk factor for cognitive decline. One recent study shows that being a smoker increases risk for dementia by 1.5 times and quitting for at least 3 years reduces much of that risk. [13] One in twelve people over 65 smoke.

In contrast, almost half of all people over 65 have raised homocysteine [14] which increases risk for cognitive impairment by up to ten times, according to Chinese research published last year[15]. Lowering homocysteine with B vitamins, and sufficient omega-3, would virtually eliminate that risk. This suggests that targeting B vitamins and omega-3 would be about twenty times more impactful in preventing dementia than quitting smoking. Yet the need for supplemental intake of these nutrients is not part of the Apple Tree protocol.

If you’d like to test your cognitive function and find out how to reduce your risk, register here and join our citizen science campaign.

References

[1] Jernerén F, Elshorbagy AK, Oulhaj A, Smith SM, Refsum H, Smith AD (2015). Brain atrophy in cognitively impaired elderly: the importance of long-chain ω-3 fatty acids and B vitamin status in a randomized controlled trial. Am J Clin Nutr. 2015 Jul;102(1):215-21

[2] Oulhaj, A et al, ‘homocysteine as a predictor of cognitive decline in Alzheimer’s Disease’, Int J Geriatric psychiatry, 25(1): 82-90 (2010)

[3] van Soest, A.P.M., van de Rest, O., Witkamp, R.F. et al. DHA status influences effects of B-vitamin supplementation on cognitive ageing: a post-hoc analysis of the B-proof trial. Eur J Nutr (2022). https://doi.org/10.1007/s00394-022-02924-w

[4] Jernerén F, Cederholm T, Refsum H, Smith AD, Turner C, Palmblad J, Eriksdotter M, Hjorth E, Faxen-Irving G, Wahlund LO, Schultzberg M, Basun H, Freund-Levi Y. Homocysteine Status Modifies the Treatment Effect of Omega-3 Fatty Acids on Cognition in a Randomized Clinical Trial in Mild to Moderate Alzheimer’s Disease: The OmegAD Study. J Alzheimers Dis. 2019;69(1):189-197. doi: 10.3233/JAD-181148. PMID: 30958356.

[5] Walsh S, Merrick R, Richard E, Nurock S, Brayne C. Lecanemab for Alzheimer’s disease. BMJ. 2022 Dec 19;379:o3010. doi: 10.1136/bmj.o3010. PMID: 36535691.

[6] Li M, Li W, Gao Y, Chen Y, Bai D, Weng J, Du Y, Ma F, Wang X, Liu H, Huang G. Effect of folic acid combined with docosahexaenoic acid intervention on mild cognitive impairment in elderly: a randomized double-blind, placebo-controlled trial. Eur J Nutr. 2021 Jun;60(4):1795-1808. doi: 10.1007/s00394-020-02373-3. Epub 2020 Aug 28. PMID: 32856190.

[7] Yu JT, Xu W, Tan CC, Andrieu S, Suckling J, Evangelou E, Pan A, Zhang C, Jia J, Feng L, Kua EH, Wang YJ, Wang HF, Tan MS, Li JQ, Hou XH, Wan Y, Tan L, Mok V, Tan L, Dong Q, Touchon J, Gauthier S, Aisen PS, Vellas B. Evidence-based prevention of Alzheimer’s disease: systematic review and meta-analysis of 243 observational prospective studies and 153 randomised controlled trials. J Neurol Neurosurg Psychiatry. 2020 Nov;91(11):1201-1209. doi: 10.1136/jnnp-2019-321913. Epub 2020 Jul 20. PMID: 32690803; PMCID: PMC7569385.

[8] Huang Y, Deng Y, Zhang P, Lin J, Guo D, Yang L, Liu D, Xu B, Huang C, Zhang H. Associations of fish oil supplementation with incident dementia: Evidence from the UK Biobank cohort study. Front Neurosci. 2022 Sep 7;16:910977. doi: 10.3389/fnins.2022.910977. PMID: 36161159; PMCID: PMC9489907.

[9] Jeong SM, Park J, Han K, Yoo J, Yoo JE, Lee CM, Jung W, Lee J, Kim SY, Shin DW. Association of Changes in Smoking Intensity With Risk of Dementia in Korea. JAMA Netw Open. 2023 Jan 3;6(1):e2251506. doi: 10.1001/jamanetworkopen.2022.51506. PMID: 36656579; PMCID: PMC9857334.

[10] Beydoun MA, Beydoun HA, Gamaldo AA, Teel A, Zonderman AB, Wang Y. Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis. BMC Public Health. 2014 Jun 24;14:643. doi: 10.1186/1471-2458-14-643. PMID: 24962204; PMCID: PMC4099157.

[11] Witte AV, Kerti L, Hermannstädter HM, Fiebach JB, Schreiber SJ, Schuchardt JP, Hahn A, Flöel A. Long-chain omega-3 fatty acids improve brain function and structure in older adults. Cereb Cortex. 2014 Nov;24(11):3059-68. doi: 10.1093/cercor/bht163. Epub 2013 Jun 24. PMID: 23796946.

[12] Cummings JL, Goldman DP, Simmons-Stern NR, Ponton E. The costs of developing treatments for Alzheimer’s disease: A retrospective exploration. Alzheimers Dement. 2022 Mar;18(3):469-477. doi: 10.1002/alz.12450. Epub 2021 Sep 28. PMID: 34581499; PMCID: PMC8940715.

[13] Lu Y, Sugawara Y, Zhang S, Tomata Y, Tsuji I. Smoking cessation and incident dementia in elderly Japanese: the Ohsaki Cohort 2006 Study. Eur J Epidemiol. 2020 Sep;35(9):851-860. doi: 10.1007/s10654-020-00612-9. Epub 2020 Feb 15. PMID: 32060675; PMCID: PMC7525275.

[14] Pfeiffer CM, Osterloh JD, Kennedy-Stephenson J, Picciano MF, Yetley EA, Rader JI, Johnson CL. Trends in circulating concentrations of total homocysteine among US adolescents and adults: findings from the 1991-1994 and 1999-2004 National Health and Nutrition Examination Surveys. Clin Chem. 2008 May;54(5):801-13. doi: 10.1373/clinchem.2007.100214. Epub 2008 Mar 28. PMID: 18375482.

[15] Teng Z, Feng J, Liu R, Ji Y, Xu J, Jiang X, Chen H, Dong Y, Meng N, Xiao Y, Xie X and Lv P (2022) Cerebral small vessel disease mediates the association between homocysteine and cognitive function. Front. Aging Neurosci. 14:868777. doi: 10.3389/fnagi.2022.868777