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Tuesday, 28 November, 2000, 00:27 GMT
Low IQ 'linked to later dementia'
baby brain
Intrinsic factors govern intelligence and dementia
Lower childhood IQ may be linked to development of dementia later in life, Scottish researchers believe.

A study based on school records of children born in 1921 has found that those with the lowest scores in intelligence tests are significantly more likely to develop dementia.

Although the research is interesting, it is clearly not the case that only people with low IQ develop dementia

Harry Cayton, Alzheimer's Society
The link with childhood IQ becomes apparent at age 64, is stronger at age 72 and stronger still at age 77.

Study author Professor Lawrence Whalley, from Aberdeen University, said: "Our research showed that there is something intrinsic rather than environmental that contributes to the development of dementia and people believe that intrinsic element is genetic."

Professor Whalley and his colleagues, geriatrician Dr John Starr and Edinburgh psychologist Professor Ian Deary believe that the same genes that determine intelligence may also be responsible for delaying the onset of dementia.

"There are many, many genes linked to intelligence but it appears some will have a compensatory response that will delay the onset of dementia and may also play a part in aging as well," Professor Whalley told BBC News Online.

The study suggests that individuals at risk of developing dementia may be targeted for gene therapy in future years.

And crucially, Professor Whalley says it is an argument "to encourage people to develop their children's brains as best they can, including by nutritional means".

The Scottish study involved reviewing the intelligence test scores of 87,498 11-year-olds who had sat tests in 1932.

The school records were uncovered by Professor Whalley's wife as part of her work as an educationalist.

Previous data

Professor Whalley had previously completed a study funded by the Medical Research Council into development of early onset dementia over a 15-year period from 1984.

He was able to establish that the IQ test results did not link to early onset dementia.

But, the researchers were able to track down 900 people from those who had sat the 1932 test who still lived in Aberdeen.

By looking at this group, Professor Whalley said it was possible to conclude that "childhood mental ability contributes to late onset dementia".

The lower the expected childhood IQ the more likely an individual was to have developed dementia after age 64, with the link becoming more significant with age.

A volunteer group from the 900 people was also invited to repeat the 1932 test and scores were virtually the same.

"The social circumstances and the material circumstances of these people have improved dramatically but their intelligence has stayed the same - that is something intrinsic rather than the environment," Professor Whalley said.

Harry Cayton, chief executive of the Alzheimer's Society said the cause of Alzheimer's Disease is most likely to be a combination of factors, including lifestyle, genetics and environment

"Although the research is interesting, it is clearly not the case that only people with low IQ develop dementia - the late Iris Murdoch is an obvious example of a highly intelligent woman who developed this devastating disease," he added.

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