Major depressive disorder in vulnerable groups of older adults, their course and treatment, and psychiatric comorbidity.

This study (1) examines the prevalence of DSM-IV MDD across different demographics, especially the vulnerable ones; (2) identifies clinical characteristics of DSM-IV MDD, such as onset, course, and treatment; and (3) evaluates the comorbidity of DSM-IV MDD with anxiety disorder, substance-use disorder, and personality disorder.