Brain-derived neurotrophic factor: a bridge between major depression and Alzheimer's disease?

Cognitive impairment is common in major depression (MD) patients, with these individuals incurring increased risk for development of Alzheimer's disease (AD). Further, depressive symptoms are common in AD patients. This apparent convergence suggests pathogenic factors common to AD and MD. Since decreased brain-derived neurotrophic factor (BDNF), a member of the neurotrophic factor family, is related to both AD and MD, the author suggests that BDNF could be a bridge between AD and MD, explaining both the depressive symptoms in AD, and, cognitive impairment in MD. Evidence supporting this hypothesis suggests that early antidepressants treatment for aged MD patients may decrease the risk of AD, and agents that increase central BDNF may offer an alternative treatment for MD patients with cognitive impairment and/or for AD sufferers with depressive symptoms.