Dementia is preventable – and can be spotted from as young as 35

A new study in the British Medical Journal has found that it’s diet, not genes, that is causing dementia. Eight simple diet and lifestyle changes can cut your risk by up to two-thirds.

Written by Becky Hardy
Published 12.09.2023

Improving your diet and lifestyle can cut your future risk of developing dementia by a massive nine times.

That’s according to a new study in the British Medical Journal, which has investigated age-related cognitive decline and dementia.

Significantly, this study also shows that it makes no difference whether you inherit the ApoE4 ‘Alzheimer’s gene’ that one in five people carry, you can still positively reduce your risk of developing dementia by simple diet and lifestyle changes.

  1. Eating a healthy diet is the most important prevention step
  2. This is followed by an active lifestyle
  3. Then keeping your brain active intellectually
  4. Then keeping your body active physically through exercise
  5. Then regular social interactions

Eating a healthy diet was about twice as important as exercise in predicting cognitive decline.

The study, published earlier this year, followed more than 30,000 people for over a decade and found that those with a healthy diet were about seven times less likely to have age-related cognitive decline or dementia than those with an ‘average’ diet, and about nine times less likely to develop dementia than those with an unfavourable diet.

The assessment of a healthy diet was based on intake of fish, eggs, fruits, vegetables, legumes, nuts and tea, among other foods known to predict lower risk.

“These results provide an optimistic outlook, as they suggest that although genetic risk is not modifiable, a combination of more healthy lifestyle factors are associated with a slower rate of memory decline, regardless of the genetic risk,” wrote the study authors.

Diet to prevent dementia and Alzheimers


This study has been warmly welcomed by charity Food for the Brain, as it backs up their own research and the work they have been actively carrying out for 10 years to help people reduce their risk of age-related cognitive decline.

Food for the Brain offers a free Cognitive Function Test, which assesses your memory. Almost 380,000 people have taken the test so far and, according to research by the NHS and University College London, 88% have found it useful.

You can then complete their Dementia Risk Index, which tells you exactly what’s driving your risk up and what to do about it.

Diet to prevent dementia and Alzheimers

And by downloading Food for the Brain’s COGNITION app, you can also track your progress and get support to help you dementia-proof your diet and lifestyle.

These online tests assess all the same risk factors the British Medical Journal study has shown impact a person’s future risk: diet, active physical, intellectual, social lifestyle, smoking and drinking habits.

“Genes can only exert effects via non-genetic mechanisms and these mechanisms are often susceptible to modification by, for example, improving one’s diet,” explains Professor David Smith from Oxford University, one of the charity’s scientific advisors.

“This study shows that diet and lifestyle are much more important than inheriting a gene variant such as ApoE4. Less than 1% of Alzheimer’s is directly caused by genes. With no clinically effective drugs and minimal role of genes, this study confirms that the focus must be on making diet and lifestyle changes that reduce the risk of developing dementia, as Food for the Brain is doing.

“It also shows that switching from an average to a healthy lifestyle, with positive diet changes being key, can dramatically reduce a person’s future risk of developing cognitive decline and dementia.”

Dementia prevention by diet as young as 35


Risk for dementia can be detected from the age of 35 and subtle changes, picked up by Food for the Brain’s cognitive function test, can be seen up to 40 years before a diagnosis.

The charity wants anyone over 35 to take the test and start making positive diet and lifestyle changes.

“The average person can cut their future risk by three quarters, just by making simple diet and lifestyle changes,” says Patrick Holford, who is directing the Alzheimer’s prevention project.

“This prevention approach, if we reach enough people, could cut cases of dementia in the UK by a third. That’s why we are urging everyone over 35 to tell everyone they know to take the free and scientifically- validated test at Food for the Brain.

“Alzheimer’s dementia, which accounts for the vast majority of dementia, is irreversible. But it is preventable, as this study shows.”


Earlier in the year, world experts at the Alzheimer’s Prevention Conference – organised by Food for the Brain – identified four easy ways that could reduce our risk of dementia by half.

Omega-3 fish oils to prevent dementia

1. Supplementing omega-3 fish oils

According to a new study of almost half a million participants of the UK’s Bio Bank, supplementing fish oils cuts dementia risk.[1] This new research was presented at the conference by China’s leading dementia prevention expert from Shanghai’s Fudan University, Professor Jin-Tai Yu.

Other studies reported by Dr Simon Dyall, clinical neuroscientist at the University of Roehampton, have shown that a higher intake of fish was associated with cutting the risk of Alzheimer’s disease by a third.

“Half your brain is fat, and a type of omega-3 called DHA has a very important role in the communication between brain cells,” says Dyall.

[1] Yu JT et al, Circulating polyunsaturated fatty acids, fish oil supplementation, and risk of incident dementia: a prospective cohort study of 440,750 participants, BMC Medicine (pending publication)

Vitamin B supplements to prevent Alzheimer and dementia through diet

2. B Vitamins

“Lowering blood homocysteine levels, an established indicator of Alzheimer’s risk, with B vitamins is a most promising treatment,” says Professor Yu. Raised homocysteine is found in one in two people over 70.

In a trial at Oxford University by Professor David Smith, giving high-dose B vitamins versus placebos resulted in 52% less brain shrinkage and little further memory loss.

Combining omega-3 and vitamin B is also important. Scientists in the trial found that those with low omega-3 DHA blood levels had no benefit from the B vitamins, while those with high omega-3 DHA had 73% less shrinkage and almost nine times less shrinkage of the Alzheimer’s-related areas of the brain.

“Research shows that you get impressive results if you give omega-3 and B vitamins together, rather than on their own,” said Professor Smith.

Exercise and diet to combat dementia and Alzheimer

3. Exercise

“For many people, the worst thing they can do for their brain is to retire.”

Those were the words of another expert at the conference – Tommy Wood, Assistant Professor at the University of Washington – who showed that your muscle mass predicts brain volume.

“Exercise, especially resistance exercise, is important because it makes the brain do things that keep it healthy, such as growth and repair,” he says. “When they aren’t stimulated, the health of brain tissues deteriorates, with a knock-on effect on memory and thinking.”

And it’s not just physical exercise that does this. We also benefit from the mental exercise involved in activities like solving puzzles or learning a new language.

Reduce sugar to prevent dementia Alzheimer

4. Sugar

“Sugar levels at age 35 predict Alzheimer’s risk later in life”

 While it has long been known that diabetics have a much higher risk for dementia, a recent study at Boston University School of Medicine found that higher blood sugar levels at age 35, but still in the ‘normal’ non-diabetic range, predict Alzheimer’s later in life.[1]

Talking at the conference, Professor Robert Lustig, from the University of California, said: ”a high level of sugar and insulin in the blood – linked with a high carbohydrate diet – is definitely a driver for Alzheimer’s.”

[1] Yu JT et al.

The conference went further to identify eight domains of risk – in other words, four more actions you can take to reduce your risk of dementia:

  • eating antioxidants from fruit and veg
  • having a healthy gut
  • sleeping well
  • controlling stress

By making all eight diet and lifestyle changes earlier in life, we could reduce our risk of dementia by two-thirds.

Find out more about how you can reduce your risk of dementia on Food for the Brain’s website.

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