Obesity linked to faster rate of mental decline, study finds

OBESITY is linked to faster memory loss, new research has discovered.

The study found that people who were obese and had other risk factors including high blood pressure experienced a 22.5 per cent faster decline in mental abilities than normal weight individuals.

The researchers, from University College London and the French research institute INSERM, followed more than 6,000 UK civil servants who started the study with an average age of 50. Over ten years the participants took tests on memory and other thinking and reasoning skills three times.

At the start of the study the people were assessed for Body Mass Index and other risk factors including high blood pressure, low levels of “good” cholesterol, high blood sugar or taking diabetes medication and high levels of certain fats in the blood. Even at the start of the study there was a big difference between normal weight participants and those who were both obese and had other risk factors.

The author of the study, Dr Archana Singh-Manoux said: “Everyone experiences a decline in mental abilities with ageing, but it was as if the obese group were seven years older.”

Some of Dr Singh-Manoux’s previous work showed this cognitive decline can start at 45, whereas it was previously thought there was no change before the age of 60. However the abilities of the obese group declined much faster.

There was only a small difference between the obese and otherwise healthy group and the obese with other risk factors group.

Dr Singh-Manoux said: “The study provides evidence against the concept of ‘metabolically healthy obesity’ that has suggested that obese people without metabolic risk factors do not show negative cardiac and cognitive results compared to obese people with other risk factors.”

Professor Iain Broom, director of the Centre for Obesity Research and Epidemiology at Robert Gordon University in Aberdeen, said: “This doesn’t surprise me. The hardening of the arteries caused by these metabolic factors includes those supplying the brain, and the reduced blood flow to the brain could impair cognitive function.

“What I would like to know is the results for those patients who were not obese but had the metabolic risk factors to determine whether it is these or the obesity having the greater effect on mental abilities. This would allow the appropriate allocation of obesity as an independent risk factor.”

Dr Lynda Williams from the Rowett Institute of Nutrition and Health in Aberdeen said: “We’ve been doing studies on mice feeding them a high fat diet. When we do this we see genes light up in the brain associated with cognitive decline.”

A Scottish Health Survey published last autumn found that 27.4 per cent of adults aged 16-64 in Scotland were obese in 2010. In addition, more than 150,000 children were obese and 63 per cent of the population was considered overweight.