SUMMARY
Mood disorders manifest across the life span yet often go undiagnosed and untreated. Increasingly, Major Depressive Disorder (MDD) in the older adult is recognized as a frequently occurring, heterogeneous psychiatric illness that impacts the individual and family, one's physical health, and society. Women are more likely to be diagnosed with MDD than men and therefore it is important to identify specific risk factors and other distinguishing features. This article reviews the descriptive characteristics, epidemiology, etiology and pathophysiology, course and natural history, and assessment and treatment of MDD with specific focus on women and aging.