Each standard-deviation increment of BDNF was associated with a 33% lower risk for AD or dementia. Compared with the bottom quintile, BDNF levels in the top quintile were associated with less than half the risk for AD or dementia. However, these links were restricted to men and women over age 80, women under age 80, and to individuals with a college education or higher.
"This is a potentially important study from the perspective of reducing the risk of dementia," Dilip Jeste, M.D., chair in aging at the University of California, San Diego, and immediate past previous APA president, told Psychiatric News. "BDNF has been previously shown to be related to lifestyle factors and interventions. One study even reported an increase in BDNF in individuals with schizophrenia who received cognitive-enhancement therapy. Continued research on BDNF and related neurotrophic factors in people at risk of dementia is necessary to help develop interventions to treat and prevent cognitive deficits in older adults."
These results have clinical implications, Seshadri told Psychiatric News. For example, blood levels of BDNF might be used to help predict risk for AD in older adults. Or giving BDNF to older people might prevent or counter AD symptoms. "We need to study the benefits and potential side effects of giving BDNF to people. Ways of doing this"—for example, using agonists that would cross the blood-brain barrier into the brain—are being studied, she noted. And interestingly, lithium, long used to treat bipolar disorder, has been found to increase BDNF levels in individuals with Huntington's disease, she pointed out. So it might also possess some effectiveness against AD. Indeed, preliminary evidence reported in the May 2012 Drugs and Aging bolsters this possibility.
More information about Alzheimer's and BDNF can be found in the Psychiatric News article, "For Now, Preventive Efforts Are Best Alzheimer's Weapon," and in the American Psychiatric Publishing book, Clinical Manual of Alzheimer Disease and Other Dementias.