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Wednesday, 12 July, 2000, 14:05 GMT 15:05 UK
High fat diet link to Alzheimer's
Dairy products
High fat foods may increase the risk of dementia
Eating a high fat diet may increase the risk of developing Alzheimer's disease, say scientists.

They have found people who have a certain variant of a gene are at risk.

The gene known as ApoE has already been linked to the progressive brain disease.

It plays a role in the transport and disposal of cholesterol in the body.

What this study tells us is that we need to look a lot harder at people's habits

Professor Grace Petot, Case Western Reserve University

Researchers have examined the impact of a variant of the gene known as ApoE4.

They found that people aged 40 to 59 who had the ApoE4 variant were four times more likely to develop Alzheimer's - even if they kept their fat intake down.

If they ate a diet in which more than 40% of calories came from fat the risk was raised a massive 29 times.

The risk also applied to younger people. High fat consumers aged 20 to 39 with the ApoE4 gene were 23 times more likely than healthier eaters without the variant to develop Alzheimer's in later life.

The research, led by nutrition expert Professor Grace Petot, from Case Western Reserve University in Cleveland, Ohio, was reported at the World Alzheimer Congress 2000 meeting taking place in Washington DC.

Fat Consumption

Professor Petot said: "What this study tells us is that we need to look a lot harder at people's habits, particularly since we saw an association between fat consumption at a relatively early age and the subsequent development of Alzheimer's disease."

The scientists carried out a retrospective analysis that examined foods eaten by 304 men and women, including 72 with Alzheimer's disease, throughout their lives.

Participants were, on average, aged in their 70s when the study began in 1991.

In general, people with the gene variant who also consumed the highest fat diets were seven times more likely to develop Alzheimer's than individuals with the susceptibility mutation who ate less fat.

Professor Petot said it was possible that when fat was broken down by the body it released substances known as free radicals that can cause tissue damage, and might precipitate the development of Alzheimer's symptoms.

Dr Richard Harvey, research director at the Alzheimer's Society in the UK, said: "Because ApoE4 is protein involved in transporting fats around the body, it is very reasonable to examine the connection between dietary fat, ApoE4 and Alzheimer's disease.

"This study gives a clue that there may be a connection.

"We also know that ApoE4 and dietary fat intake are risk factors for vascular disease - both affecting the heart (increasing the risk of heart attack) and cerebrovascular (increasing the risk of stroke).

"There is growing evidence that Alzheimer's may be precipitated or made worse by vascular disease, and this may be the link between ApoE4, dietary fat and Alzheimer's.

"The next step would be to investigate whether modifying the diet of those who are at highest risk would actually reduce their risk of AD."

Disease on the increase

Alzheimer's affects around 500,000 people in the UK. The number of sufferers is expected to rise 50% over the next 40 years because of the ageing population, but at present there is no cure.

ApoE4 (apolipoprotein E epsilon-4) is the only confirmed genetic risk factor for Alzheimer's disease.

Inheriting one copy of the variant increases the risk four times, on average. Inheriting two copies is said to increase the risk 16-fold.

However even inheriting two copies of the gene does not mean an individual will inevitably develop Alzheimer's.

For this reason genetic screening for Alzheimer's is not carried out in the UK.

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