Older obese people with mild cognitive impairment who lose a small amount of weight may see some improvement on tests of thinking skills, according to a new study.
Mild cognitive impairment causes slight but noticeable declines in memory and thinking skills, and increases the risk of Alzheimer’s or other forms of dementia developing later.
“Increased adiposity has been correlated with reduced volume in a number of brain regions,” said the lead study from the University of Sao Paulo School of Medicine in Brazil.
About the study
The researchers divided 80 obese people over age 60 (average age 68) with mild cognitive impairment into two groups, one of which received usual medical care while the other also met in group nutritional counseling meetings for a year.
All the participants were advised to meet physical activity guidelines, including doing at least 150 minutes of moderate-intensity aerobic exercise or walking throughout the week, or if limited due to health conditions, aiming to be as physically active as possible.
The nutritional counseling group also met about 28 times for one-hour sessions, which included advice on eating a diet rich in fibre, fruits, vegetables and whole grains, and on how to achieve a daily 500-calorie deficit.
At the start, all the participants had a body mass index (BMI) of at least 30, the lower limit for obesity.
As BMI decreased, cognitive function improved
By the one-year point, BMI had decreased by an average of 1.7 points. The proportion of those who were physically active did not change. The process of recruiting volunteers included information on the risks of obesity, which may have increased motivation to lose weight in both groups.
Performance on a battery of physical tests tended to improve during the study. As BMI decreased, thinking skills, verbal memory, language and executive function appeared to increase based on cognitive tests. The improvements were more pronounced for younger seniors.
Even with the small weight changes that occurred, the decrease in fat was correlated with cognitive improvement.
None of the participants had conditions like depression, heart failure or alcoholism that would interfere with weight loss or cognition.
Caloric restriction seems to activate processes that are good for the brain, Weight loss itself may not need to be the goal for elderly people, since those in this study lost relatively little weight.
It is still too soon for older people with thinking difficulties to ask their doctors about calorie restriction for improving cognition, the researchers said, and it may never be a safe strategy for certain people, including cancer patients and pregnant women.
Source: Journal of Clinical Endocrinology and Metabolism, online December 29, 2015.
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