Higher BMI in Midlife Linked to Earlier Onset of Alzheimer’s

Being overweight or obese at age 50 may lead to earlier onset of Alzheimer’s disease, according to a new study in Molecular Psychiatry.

Researchers found that each unit increase in midlife body mass index (BMI) accelerated the onset of Alzheimer’s by 6.7 months.

Lead study author Madhav Thambisetty, MD, PhD, and colleagues in the National Institute on Aging wanted to determine if there were any links between midlife BMI and age at onset of Alzheimer’s, severity of Alzheimer’s neuropathology, and fibrillar brain amyloid deposition during aging.
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They analyzed data from nearly 1,400 participants in the Baltimore Longitudinal Study of Aging (BLSA), one of the longest running studies of human aging in North America. Cognitively healthy at baseline, all participants completed cognitive assessments every 1 to 2 years for the duration of the nearly 14-year study.

About 10% of the group (142 patients) eventually developed Alzheimer’s disease—and the authors found a relationship between higher BMI and earlier onset of the disease in these patients.

The researchers also looked at two subsamples of BLSA that included:

• 191 participants who underwent autopsy and neuropathological assessment.

• 75 healthy individuals underwent brain imaging to detect amyloid, which is considered one of the earliest biomarkers of Alzheimer’s disease.

From examining both groups, the authors found that those with higher midlife BMI had greater levels of neurofibrillary tangles, an indicator of more severe neuropathology, and more amyloid deposits in the precuneus, a region of the brain that often shows the earliest signs of changes related to Alzheimer’s.

“In conclusion, midlife overweight predicts earlier onset of [Alzheimer’s disease] and greater burden of Alzheimer’s neuropathology,” the authors wrote. “A healthy BMI at midlife may delay the onset of [Alzheimer’s disease].”

—Colleen Mullarkey

Reference

Chuang YF, An Y, Bilgel M, Wong DF, Troncoso JC, O’Brien RJ, et al. Midlife adiposity predicts earlier onset of Alzheimer’s dementia, neuropathology and presymptomatic cerebral amyloid accumulation. Mol Psychiatry. 2015 Sep 1. [Epub ahead of print].