We know that we are born with a potential for intelligence and intelligence must be managed. A 60-year-old Scottish research made on 70,000 11-year-old children could explain the way lifestyle affects intelligence. Smoking, obesity, sedentarism and bad food could lead not only to physical diseases, but also to a dumber brain. Dementia, like Alzheimer's, seems to be partly self-induced and one's lifestyle could avoid or delay it.

"This 60-year-old study gives us a unique database of people's past mental abilities. By tracking down and retesting the people in that study we can see how their mental powers have changed over the decades and what impact their lifestyles have had on those changes," said Ian Deary, professor of differential psychology at Edinburgh University.

Deary, together with Lawrence Whalley, professor of mental health at the University of Aberdeen, has found around 1,500 persons who took part in the 1947 research. The subjects went through the tests again, completed questionnaires about their lifestyles and underwent brain MRI scans.

Lesley Main, 71, a retired violin teacher, believes her good health is due to eating well and keeping on being active, as a senior dive master in a local scuba club and going worldwide on diving trips.

"What is emerging is that people who are brighter, more socially engaged, and who live healthy lives, retain their mental faculties as well as their physical health for much longer," said Whalley.

"This project offers us a chance to determine the causes of cognitive decline and how to prevent them." said Michael Lake, director general of Help the Aged.

"Between the ages of 11 and 70-plus, the way you live can raise or lower your cognitive skills by around 10%," said John Starr, a consultant and researcher in geriatric medicine at the Royal Victoria hospital in Edinburgh, involved in the research.
Smoking appeared to be a main factor in IQ decrease.

"If you smoke through life it typically reduces your IQ by about 2%. This might explain the memory lapses and slower thinking suffered by many people beyond the age of 60, and might even explain why some tip over into dementia." said Starr.

Psychotropic drugs against depression and other mental issues inflicted a similar decline. Oppositely, physical exercise and a high-quality diet (especially rich in omega 3 fatty acids, like those encountered in fish oil) boosted mental skills.
The team was amazed to find men of this generation scored far better than women, having an average IQ mark several points above their female counterparts.

"We think this is because women then did not have so many opportunities to get an education or hold stimulating jobs. Intellectual stimulation provides protection against later decline, and men had more opportunities. One small group of men has been identified as the "elite old" because, they defy aging logic", said Whalley.

About a dozen men out of the 500 displayed high levels of fitness and great IQ scores which appeared to be still improving.

Most vitamins and minerals appeared not to affect intelligence, except folic acid (vitamin B9) and vitamin B12, which lower the amounts of homecysteine, an amino acid whose high levels increase the likelihood of experiencing stroke and dementia. The brain aging was more controlled by how "white matter" behaved, as this stuff represents an insulating coat for the billions of connections between brain cells. If the white matter is harmed, the breaking brain cell connections cause mental decline.

"Such damage may result from a range of factors, some genetic but including smoking, diet and high blood pressure brought on, for example, by obesity. By contrast, people who seek out intellectual stimulation can actually enhance their brain, prompting it to build many extra connections that make it more resistant to aging." said Deary.

"It's so easy to relax into retirement and assume that you're going to just go downhill." said Margaret Lawson, of Edinburgh, a former university science technician, subject of the 1947 research.

A recent research made by Carol Brayne, professor of public health at Cambridge University, linked aging-related mental decline and dementia to levels of activity, socializing, obesity and high blood pressure.

"The brain shows a marked increase in degenerative disorders with age but there is evidence that up to 50% of dementia might be preventable." said Brayne.