Brain derived neurotrophic factor (BDNF) is a growth factor associated with decreased risk of dementia and improved cognitive function in humans. While BDNF promotes brain cell growth plasticity, its precursor form, called proBDNF, has the opposite effect, promoting cell death. The authors of a recent report investigated the relationship between blood levels of pro-BDNF and memory loss.

The effects of Alzheimer’s disease on the brain can be observed 10 to15 years before the onset of dementia, which presents the opportunity for early detection. Even though BDNF is known to cross the blood-brain barrier, whether blood levels of BDNF are reflective of BDNF activity in the brain is unclear. Establishing blood biomarkers of dementia risk provides the ability for early intervention.

The authors recruited 256 older adults (average age, 68 years) without dementia. They analyzed magnetic resonance imaging (MRI) scans of the participants’ brains and measured blood levels of BDNF and proBDNF. Participants completed questionnaires to measure memory and physical activity habits.

The investigators reported that increased age and decreased physical activity were associated with poorer memory performance. MRI findings showed decreased volume in the hippocampus, the region of the brain associated with memory, in those with worse memory scores. Finally, the authors reported that decreased blood levels of BDNF, but not pro-BDNF, were associated with worse memory performance.

These results echo earlier findings that exercise is associated with greater BDNF activity and better memory performance. The authors conclude the measuring blood levels of BDNF may be an effective strategy for early detection of dementia.

• Link to full report.

• Learn more about BDNF and brain health in our overview article.