Staying healthy and maintaining a normal weight may be good not only for your body but also for your brain. A 10-year study of 6,401 British civil servants, initially ages 39 to 63, reports an association between being overweight or obese and impaired cognitive function. Combined with other health issues (“metabolic abnormalities”) such as diabetes or high cholesterol, extra weight also increased the odds of mental decline over time. “I think that its important to point out that metabolic abnormality was predictive of poorer cognitive performance regardless of BMI, says Tammy Scott, PhD, a scientist at Tufts HNRCA Nutrition and Neurocognition Laboratory. One of the most important findings of this study, though, was that amongst metabolically healthy individuals, higher BMI was associated with worse cognitive function. Furthermore, in the metabolically unhealthy group, higher BMI was associated with greater cognitive decline over a 10-year period. This trend over time was not seen in the metabolically healthy group.” Those associations, Scott says, underline the importance of maintaining a healthy weight-not only for your physical health but, apparently, for a healthy brain as well. Like obesity and overweight, moreover, most of the metabolic abnormalities also associated with poorer cognitive performance can be combated with healthy eating and lifestyle.
10-YEAR FOLLOWUP. In the new study published in Neurology, Archana Singh-Manoux, PhD, of Hpital Paul Brousse in Villejuif, France, and colleagues compared body-mass index (BMI) and various metabolic conditions with cognitive function at baseline and after five and 10 years. Participants were assessed using tests including reasoning, memory and semantic fluency. In addition to reporting BMI, participants were asked about other health factors and were classified as “metabolically abnormal” if they had two or more conditions such as high cholesterol or triglycerides, high blood pressure, low “good” HDL cholesterol, high glucose or diabetes. Overall, 38.2% of participants were overweight and 9.1% were obese. Among all participants, 31% were categorized as metabolically abnormal, while among the obese civil servants that rate was 60.1%.
AT RISK FOR DECLINE. Singh-Manoux and colleagues reported in Neurology that lower BMI was associated with better cognition at the studys start. Over time, those with multiple markers of metabolic abnormality were more likely to develop impaired cognitive function. In follow-up mental testing, those who were both obese and metabolically abnormal were significantly more likely to show a faster rate of cognitive decline.
Researchers speculated that vascular problems associated with weight might affect brain function, along with fat-related secretions that impact the aging brain. Says Tufts Scott, “The authors speculations on the mechanisms underlying their findings seem reasonable, although further research needs to be done in this area.”