Researchers from the Icahn School of Medicine at Mount Sinai have found that greater increases, decreases, or variability in body mass index (BMI) over time are associated with an accelerated rate of cognitive decline, irrespective of whether a person was originally normal weight, overweight, or obese.
The findings, published January 20 in Alzheimer's & Dementia: the Journal of the Alzheimer's Association, indicate that in old age, a stable BMI may confer protection against cognitive decline. They also suggest that tracking BMI, which is simple to measure, at annual medical visits may point to individuals whose cognition is declining and allow for early intervention.
Progressive loss of cognition is common in older adults and its prevention and treatment is a major public health priority. Consistent evidence associates high BMI, the most commonly used measure of overweight, in midlife with poor cognitive outcomes in late life. Some studies have shown more cognitive impairment and dementia with greater BMI in old age, while others have found no association or even lower dementia risk in obese older adults. In addition, losing weight has been associated with higher dementia risk. Despite the relevance of BMI to the risk of incident cognitive impairments and the subtle but consistent decrease in BMI which accompanies old age, there is limited evidence about simultaneous changes in BMI and cognitive decline, which better reflect the natural course of both health phenomena.
To address this gap in knowledge, the research team analyzed longitudinal clinical data from approximately 16,000 older adults through the National Alzheimer's Coordinating Center, which maintains the uniform data set of participants enrolled at Alzheimer's disease centers across the United States that are funded by the National Institute on Aging, including the Alzheimer's Disease Research Center at Mount Sinai.
To be eligible for the study, participants had to be at least 60 years old and without a diagnosis of dementia, as determined by clinician consensus. The study included participants who were enrolled in these centers between September 2005 and December 2019, following them for an average of five years. All participants were administered a standardized neuropsychological battery at each visit. The study team categorized the neuropsychological tests into the following domains: memory, attention/working memory, language, and executive function. BMI was calculated based on measured weight and height at baseline and at each follow-up visit, with baseline BMI categorized into three groups based on the World Health Organization's classification of underweight or normal (2), overweight (25≤BMI2) and obese (≥30kg/m2).
"All groups had some degree of decline, including the group with stable BMI. However, the rate of decline in the non-stable BMI groups was over 60 percent faster than the rate of decline in the stable BMI group," said Michal Beeri, PhD, Professor of Psychiatry at Icahn Mount Sinai and senior author of the paper. "Disentangling the biological pathways underlying different trajectories of BMI in old age, and their contributions to brain health and disease, is necessary in order to develop potential therapeutics. Our study findings help point us in the direction of that ultimate goal, while also providing important considerations that can be assessed in the clinical management of patients as they age."
Who: Michal Beeri, PhD, Professor of Psychiatry at Icahn Mount Sinai.
This study was supported by the National Institute of Aging (AG005138 AG016976 P30 AG066514 for Dr. Sano, and R01 AG034087, R01 AG053446, R01 AG051545, R01 AG061093, AG043878); the Department of Veterans Affairs, Veterans Health Administration. The views expressed in this article are those of the authors and do not necessarily represent the views of the Department of Veterans Affairs.
Article
Michal Schnaider Beeri, PhD; Amir Tirosh, MD, PhD; Hung-Mo Lin, ScD; Sapir Golan, MSc; Ethel Boccara, BA; Mary Sano, PhD; Carolyn W. Zhu, PhD; Stability in BMI over time is associated with a better cognitive trajectory in older adults. Alzheimers & Dementia, January 20, 2022, DOI: XXX
