By JENNY HOPE
PUBLISHED: 18:05 EST, 20 August 2012 | UPDATED: 19:21 EST, 20 August 2012
- People over 50 with high blood pressure or obesity suffer accelerated memory loss and cognitive skills
- Risk factors such as heart disease and diabetes speed up the mental decline
- Obese participants’ brains aged 3.8 years more than those of a health weight
- Research supports evidence that mid-life obesity increases the risk of dementia
Obesity and high blood pressure lead to faster mental decline in the over-50s, researchers warn.
A study shows that being fat and having other risk factors for heart disease and diabetes accelerates the loss of memory and other cognitive skills.
Over the course of a decade, obese participants’ brains aged 3.8 years more than those of a healthy weight.
Memory loss: Obesity and high blood pressure accelerates memory loss and other cognitive skills
The fattest participants had a 22.5 per cent faster drop-off in test scores compared with those who were a healthy size and had fewer risk factors.
Experts warn that obesity in middle-age could be a major risk factor for developing dementia in later life, as well as conditions such as diabetes.
The claim has been strengthened after the study by scientists at the French medical research institution INSERM examining the mental skills, body mass index and general health of 6,401 adults with an average age of 50.
Researchers took note of so-called ‘metabolic abnormalities’ such as high blood pressure, low levels of ‘good’ cholesterol, high blood sugar and whether participants took diabetes medication.
A third of the participants had two or more of these risk factors, while 9 per cent were obese (defined as having a BMI above 30) and 38 per cent were overweight (with a BMI of between 25 and 29.9).
The participants then took tests on memory and other cognitive skills three times over ten years. Those who were overweight or obese and had at least two metabolic abnormalities showed the fastest decline.
More research: Study author Archana Sing-Manoux says more research is needed into the effects of genetic factors and how long people have been obese
Over the course of the study, those who were both obese and ‘metabolically abnormal’ experienced a 22.5 per cent faster decline on their scores than those who were a normal weight with no abnormalities.
Among a middle-aged sub-group of participants who had an average age of 56 at the start of testing, researchers found a decline in scores equivalent to an extra 3.8 years of ageing among those who were obese.
Scientists had speculated that relatively healthy obese people without metabolic risk factors might be protected from mental decline – but their performance also dropped off.
Study author Archana Singh-Manoux, whose work is published in Neurology, the journal of the American Academy of Neurology, said: ‘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.’
Mental decline: Relatively healthy obese people might be protected from mental decline but their performance still declined
She added that researchers should also look at test scores ‘spanning adulthood to give us a better understanding of the link between obesity and cognitive function, such as thinking, reasoning and memory’.
Experts do not know exactly why obesity affects the risk of dementia, but hardening of the arteries and high blood pressure play a role.
Previous research has also shown that abdominal obesity has a particularly harmful effect on the brain.
Jessica Smith of the Alzheimer’s Society charity said: ‘We all know that piling on the pounds is bad for your physical health, but this robust study suggests that it is bad for the head as well as the heart.
‘These results back up existing evidence that obesity in mid-life increases the risk of developing dementia.
‘One in three people over the age of 65 will die with some form of dementia.
‘The best way of reducing your risk is to eat a balanced diet, maintain a healthy weight, exercise regularly and get your blood pressure and cholesterol checked.’