Being Overweight Linked To "Severe Brain Degeneration"

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Main Category: Obesity / Weight Loss / Fitness
Also Included In: Neurology / Neuroscience;  Alzheimer's / Dementia
Article Date: 27 Aug 2009 - 11:00 PDT

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US neurologists who analyzed brain scans of elderly people discovered that being overweight is linked to brain tissue loss, or what one researcher described as "severe brain degeneration".

The study was the work of senior author Dr Paul Thompson, a professor of neurology at the University of California Los Angeles (UCLA), and lead author Cyrus A. Raji, a medical student at the University of Pittsburgh School of Medicine, and colleagues, and is to be published in the journal Human Brain Mapping, of which an early view is available online.

We already know that obesity is linked to an increased risk of several chronic diseases, including type 2 diabetes, high blood pressure and stroke. And now Thompson and colleagues have added another to the list: loss of brain tissue.

They found that obese people had on average 8 per cent less brain tissue compared to people of normal weight , while overweight people had 4 per cent less.

They defined obese as having a BMI over 30, overweight in the range 25 to 30, and normal weight 18.5 to 25.

(BMI stands for body mass index, the most widely used standard measure of obesity. It equals the ratio of a person's weight in kilos to the square of their height in metres).

Thompson described 8 and 4 per cent as "a big loss of tissue".

"It depletes your cognitive reserves, putting you at much greater risk of Alzheimer's and other diseases that attack the brain," he said.

"But you can greatly reduce your risk for Alzheimer's if you can eat healthily and keep your weight under control," he added.

For the study he and his colleagues looked at brain images from 94 people aged 70 and over who had taken part in an earlier study called the Cardiovascular Health Cognition Study.

All the participants were healthy and none was cognitively impaired when assessed five years after the scans were taken.

The researchers converted the scans into 3-D images using a high resolution method called "tensor-based morphometry" that shows a detailed anatomy of the brain.

With these images they were able to do things like examine the grey matter and the white matter and determine which parts of the brain were most affected.

They found that the obese participants had lost brain tissue in areas of the brain that are important for planning and memory (the frontal and temporal lobes), attention and executive functions (the anterior cingulate gyrus), long-term memory (the hippocampus), and movement (the basal ganglia).

Overweight participants showed brain loss in the basal ganglia, the corona radiata, the white matter, and the parietal lobe.

The findings were unaffected by taking into account age, gender and race.

Thompson said that when they looked at the scans:

"The brains of obese people looked 16 years older than the brains of those who were lean, and in overweight people looked 8 years older."

According to the World Health Organization, there are more than 300 million people worldwide whose BMI puts them in the obese category.

The National Institute on Aging, the National Institute of Biomedical Imaging and Bioengineering, the National Center for Research Resources, and the American Heart Association paid for the study.

"Brain structure and obesity."
Cyrus A. Raji, April J. Ho, Neelroop N. Parikshak, James T. Becker, Oscar L. Lopez, Lewis H. Kuller, Xue Hua, Alex D. Leow, Arthur W. Toga, Paul M. Thompson.
Human Brain Mapping, Early view, accessed 27 August 2009.
DOI: 10.1002/hbm.20870

Source: UCLA News.

Written by: Catharine Paddock, PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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