Circulating leptin was associated with a reduced incidence of dementia and Alzheimer’s disease and with cerebral brain volume in asymptomatic older adults.
High leptin levels were associated with a lower incidence of Alzheimer’s disease and dementia in a community-based study cohort, researchers reported in the December 16, 2009, issue of JAMA.
According to the researchers, a growing body of evidence suggests that leptin has beneficial effects on brain development and function. Leptin appears to mediate structure and functional changes in the hippocampus and to improve memory function. It has also been shown to increase apolipoprotein E–dependent b amyloid.
Using participants from the original cohort of the Framingham Heart Study, researchers from Boston University School of Medicine measured leptin concentrations in 785 persons without dementia. A subsample of 198 dementia-free survivors underwent volumetric brain MRI between 1999 and 2005, nearly eight years after leptin levels were measured. Two measures of brain aging—total cerebral brain volume and temporal horn volume were assessed.
During a median follow-up of 8.3 years, 111 participants developed incident dementia; 89 had Alzheimer’s disease. Higher leptin levels were associated with a lower risk of incident dementia and Alzheimer’s disease. Higher plasma leptin levels were also associated with higher total cerebral brain volume and lower temporal horn volume, although the association of leptin level with temporal horn volume did not reach statistical significance.
“Over a 12-year follow-up, this corresponds to an absolute Alzheimer’s disease risk of 25% for persons with the lowest levels of leptin compared to a 6% risk for persons with the highest levels,” said senior author Sudha Seshadri, MD, who is an Associate Professor of Neurology at the Boston University School of Medicine.
“If our findings are confirmed by others, leptin levels in older adults may serve as one of several possible biomarkers for healthy brain aging and, more importantly, may open new pathways for possible preventive and therapeutic intervention,” she concluded.
—Glenn Williams