Why Brains Shrink? …Obesity!

September 08, 2009

Results from a recent study conducted by scientists from UCLA and the University of Pittsburg relating body mass index (BMI) and brain volume were recently released in the scientific publication Human Brain Mapping - results were staggering.

Results from a recent study conducted by scientists from UCLA and the University of Pittsburg relating body mass index (BMI) and brain volume were recently released in the scientific publication Human Brain Mapping - results were staggering. Controlling for age, gender and race - theoretically flattening the playing ground - researchers studied virtual images, focusing on brain structure and volume, of 94 elderly subjects (average age 77.3), displaying normal cognitive function.
In the elderly, brain atrophy or deterioration is related to a decrease in cognitive function and dementia, including Alzheimer’s disease. Previous studies have related the intermediate risk state for Alzheimer’s disease, to hypertension, diabetes, heart disease, and others. High BMI and its relation to brain structure in elderly free of Alzheimer’s had yet to be investigated.  
Results compared those considered normal weight and obese subjects as well as normal weight and overweight subjects. Normal weight correlates to a BMI range 18.5-25, overweight BMI 25-29 and obese BMI 30+. The results proved both significant and shocking! 
Normal Weight versus Obese Subjects: Obese subjects demonstrated eight percent less brain volume than their normal weight counterparts. Degeneration was seen in the frontal and temporal lobes- critical for reasoning and judgment, the anterior cingulate gyrus (critical for decision making and emotion), the hippocampus (responsible for long term memory), and the basal ganglia (integral for motor control and movement). The obese subjects’ physical brain age was determined to be 16 years senior to their leaner counterparts.    
Normal Weight versus Overweight Subjects: In comparing normal weight subjects with those considered overweight, BMI range 25-29, researchers found a four percent decline in brain volume. In this group, brain degeneration occurred in the basal ganglia as well as the parietal lobe (important in determining spatial sense and navigation). Overweight subjects’ brain age was thought to be eight years older than the more physically fit.  
While the studies’ subjects showed no outward signs of cognitive impairment, the authors predict that the observed premature aging and loss of brain volume would put heavier subjects at a greater risk of Alzheimer's disease and other degenerative brain diseases. A shrunken and aged brain, as seen in the overweight and obese subjects, is less robust and resilient as compared with normal weight subjects. Memory loss, movement problems and decreased cognitive ability are far more likely to surface at an earlier age in overweight and obese patients.
According to the World Health Organization, over one billion people worldwide are overweight, and 300 million are considered obese. We also know that in our country alone, the prevalence of obesity has increased or stayed the same in all 50 states, despite major governmental and public health initiatives. The study’s researchers are optimistic about their findings, both to further understand the brain systems affected and to create and gauge success of preventative and protective interventions. In the meantime, the best prevention seems to be the good old fashioned prescription of regular exercise and a varied and balanced diet.