A healthy diet of oily fish, fruit and vegetables could reduce the risk of developing Alzheimer’s disease, according to scientists.

The study found that old people with high levels of omega 3 fatty acids and vitamins C, D, E and B suffered from less brain shrinkage and had higher scores on mental agility tests than those with low levels of the nutrients.

Omega 3 fatty acids and vitamin D are primarily found in oily fish, such as mackerel, while B vitamins and antioxidants C and E are primarily found in fruits and vegetables.

People whose blood had higher levels of trans fats, found mainly in cakes and fried foods, had the worst cognitive scores.

However, the nutrients did not seem to be effective when found in high concentrations in isolation, suggesting that simply taking fish oil capsules or taking vitamin C tablets may be less effective at protecting against cognitive decline than eating a balanced diet.

The brain typically shrinks by about 10 per cent each decade, even in healthy older people, and the rate of brain atrophy is known to be more rapid in those who go on to develop Alzheimer’s.

Scientists said the findings suggested that in the future dietary therapy could be used to delay the onset and slow the progression of Alzheimer’s disease, although they added that further clinical trials would be needed to provide conclusive evidence.

There are currently 820,000 people in the UK affected by dementia but few treatments have been shown to be effective at preventing or slowing the rate of decline.

Professor Gene Bowman, of Oregon Health & Science University in Portland, who led the study, said: “If you have a family history of Alzheimer’s, these are dietary patterns that you might want to seriously consider.”

The study, published today in the journal Neurology, involved 104 people with an average age of 87 and no diagnosed memory or thinking problems. Blood tests were used to determine the levels of various nutrients present in the blood of each participant. All of the participants also took tests of their memory and thinking skills and 42 had MRI scans to measure their brain volume.

The study suggested that a significant amount of the variation in both brain volume and thinking and memory scores could be explained by differences in nutrient. For the thinking and memory scores, the nutrient biomarkers accounted for 17 per cent of the variation in the scores. Other factors such as age, number of years of education and high blood pressure accounted for 46 per cent of the variation.

For brain volume, the nutrient biomarkers accounted for 37 per cent of the variation.

“These results need to be confirmed, but obviously it is very exciting to think that people could potentially stop their brains from shrinking and keep them sharp by adjusting their diet,” Professor Bowman said.

A second study, also published today in Neurology, showed that the rate of brain shrinkage is a useful marker for whether a person will go on to develop Alzheimer’s disease.

Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, said: “The ability to predict who will develop Alzheimer’s disease is a key target for dementia research, as it would allow new treatments to be trialled early, when they are more likely to be effective. These findings add weight to existing evidence that Alzheimer’s begins long before symptoms appear, although it’s important to note that the study did not assess who went on to develop the disease.”


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