A study published in the journal Neurology finds that obesity (in the setting of other health problems) is associated with hastened cognitive decline.
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PROBLEM: Obesity has been linked to a variety of metabolic problems, such as high blood pressure, heart disease, and diabetes. Less is known, however, about the relationship among these conditions, obesity, and the brain.
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METHODOLOGY: French researchers surveyed 6,401 adults ranging in age from 31 to 63 in the early 1990s. The study participants reported their body mass index as well as metabolic risk factors such as blood pressure, high glucose levels, high triglycerides, and low HDL cholesterol. Just over half of participants were of a normal weight; 38 percent were overweight; and 9 percent were obese. Of all participants, 31 percent had two or more of the four aforementioned metabolic abnormalities. After the baseline survey, participants were subjected to three rounds of cognitive tests over the next decade and a half to examine brain performance.
RESULTS: Cognitive decline progressed fastest in those who were both obese and metabolically abnormal. Participants who were obese but did not have one of the measured metabolic abnormalities (which is rare), though, showed no increase in cognitive decline.
CONCLUSION: Among people with hypertension, elevated blood glucose (diabetes/pre-diabetes), high triglycerides, and/or low HDL, obesity was associated with significant hastening of cognitive decline.
IMPLICATION: Obesity -- and more crucially, the metabolic syndromes that often accompany it -- may be a risk factor for early-onset dementia and other cognitive diseases. In addition to the known myriad benefits of weight management, it may also yield indirect benefits for the brain.
SOURCE: The full study, "Obesity Phenotypes in Midlife and Cognition in Early Old Age," is published in the journal Neurology.