August 21, 2012

Research Suggests Obesity Leads To Rapid Mental Decline

Brett Smith for - Your Universe Online

New research suggests that obesity and its associated risk factors lead to a more rapid mental decline in persons over 50, according to a report in the journal Neurology.

Although the exact relationship is unknown, a survey of over 6,400 adults found that the obese participants´ who were 56 at the start of testing were calculated to have brains that aged 3.8 years more than those who maintained a healthy weight. The most overweight participants showed a 22.5% faster drop-off in cognitive test scores.

In the study, French medical research institution INSERM tested the civil service participants, who were between 35 and 55, on memory and other cognitive skills three times over ten years. They also tracked the weight and any metabolic abnormalities in their subjects. Metabolic abnormalities were considered to be having high blood pressure or taking medication for it, low HDL or "good" cholesterol, high blood sugar or taking diabetes medication, and high triglycerides or taking medicine to lower cholesterol.

Of the study´s participants 31% had two or more metabolic abnormalities, 9% were obese, and 38% were overweight. Of the 582 obese participants, 60% met the criteria for metabolic abnormality.

Some scientists had expected that relatively healthy obese people without metabolic abnormalities might be protected from mental decline — but their testing scores dropped off as well.

"More research is needed to look at the effects of genetic factors and also to take into account how long people have been obese and how long they have had these metabolic risk factors and also to look at cognitive test scores spanning adulthood to give us a better understanding of the link between obesity and cognitive function, such as thinking, reasoning and memory," said study author Archana Singh-Manoux, of INSERM and University College in London.

She added that the study´s results punched holes in the idea that people could be overweight, yet still live a healthy lifestyle.

"We do not yet know why obesity and metabolic abnormality are linked to poorer brain performance, but with obesity levels on the rise, it will be important to delve a little deeper into this association,” said Shirley Cramer of the Alzheimer's Research UK who was not involved with the study.

One problem with the study is that it only looked at cognitive function, and not at dementia, according to some experts. Some diminished cognitive function is to be expected with aging and not all loss of function can be connected to dementia.

"While the study itself focuses on cognitive decline, previous research suggests that a healthy diet, regular exercise, not smoking and controlling blood pressure and cholesterol in midlife can also help stave off dementia,” said Cramer.

“With dementia figures spiraling towards a million, the findings suggest we should be conscious of our general health throughout life.”

This same sample group, Whitehall II prospective cohort study, was established in 1985 on 10,308 British civil servants and had provided cognitive data for several other studies, including a report from INSERM that concluded cognitive decline may begin in middle age.