Obesity Linked to Risk of Alzheimer's Disease

Alzheimer's Disease
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Obesity has been linked with a variety of serious health problems, and the latest one to add to the list is Alzheimer’s disease. A new study available on the online edition of the journal Human Brain Mapping reports that obese and overweight people have less brain tissue than people of normal weight.

This is the first study to demonstrate a link between being obese or overweight and having “severe brain degeneration,” according to Paul Thompson, senior author of the study, a member of UCLA’s Laboratory of Neuro Imaging, and UCLA professor of neurology. For this study, the researchers used brain images from 94 healthy people in their 70s who had participated in the Cardiovascular Health Study Cognition Study and converted them into detailed three-dimensional images using a technique called morphometry. They also identified the weights of the individual participants according to the Body Mass Index (BMI) and used the scale of 18.5 to 25 as normal weight, 25 to 30 as overweight, and greater than 30 as obese.

Thompson and his colleagues found that people defined as obese had 8 percent less brain tissue than people of normal weight, and that overweight people had 4 percent less tissue. According to Thompson in a UCLA news release, this represents a “big loss of tissue and it depletes your cognitive reserves, putting you at much greater risk of Alzheimer’s and other diseases that attack the brain.”

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Thompson and his colleagues observed that the brains of obese individuals looked 16 years older and those of overweight people looked eight years older than the brains of people who were of normal weight. The shrinkage of brain tissue observed in this study was found in areas of the brain associated with memory, attention, long-term memory, and movement.

A previous study (March 2008, Neurology) found that have a large abdomen increased the risk of developing dementia, including Alzheimer’s, regardless of whether individuals were of normal weight, overweight, or obese, and regardless of existing health conditions such as diabetes, cardiovascular disease, and stroke. The study found that people who were overweight and who had a large abdomen were 2.3 times more likely to develop dementia than people of normal weight and belly size.

The good news is that people can reduce their risk of Alzheimer’s disease if they follow a healthy diet and maintain a healthy weight. Results of a recent study conducted at Columbia University Medical Center found that elderly people who follow a Mediterranean diet and practice regular physical exercise have a reduced risk of developing Alzheimer’s disease.

Alzheimer’s disease is just the latest addition to the list of serious complications associated with obesity and overweight. Along with the known risks for cardiovascular disease, hypertension, and type 2 diabetes, other challenges linked with excessive body weight include an increased risk for needing a hip replacement for osteoarthritis in men, a significantly higher incidence of complications associated with spinal surgery (including blood clots, heart problems, and deep vein thrombosis), and a greater risk of gallbladder disease, sleep apnea, fatty liver disease, pregnancy complications, and certain types of cancer.

SOURCES:
Franklin et al. Annals of the Rheumatic Diseases 2009 Apr; 68(4): 536-40
National Institute of Diabetes and Digestive and Kidney Diseases
Patel N et al. Journal of Neurosurgery. Spine 2007 Apr; 6(4): 291-97
UCLA News Release, 8/25/09

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