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

BACKGROUND: Although a number of epidemiology studies of major depressive disorder (MDD) in older adults have been reported, most of them suffer four limitations: (1) the sample was not nationally representative; (2) the sample was relatively small or only one or two sociodemographic correlates of MDD were examined; (3) psychiatric comorbidity was not examined; and (4) the clinical characteristics of MDD were not reported. 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.

METHODS: We analyzed data on 8,205 individuals aged 65 or older from the National Epidemiologic Survey on Alcohol and Related Conditions (2001-2002), a nationally representative survey of the noninstitutionalized U.S. household population. The Alcohol Use Disorder and Associated Disabilities Interview Schedule-DSM-IV version assessed MDD, anxiety, substance use, personality disorders, and pathological gambling. The survey also included demographic characteristics: age, sex, race/ethnicity, marital status, education, employment status, personal income, urban vs. rural residence, and region of the country.

RESULTS: Marital status and gender were associated with MDD, whereas race and socioeconomic characteristics were not. Specifically, the prevalence rates of past-year MDD were significant greater for females (3.6%) than males (2.0%) and higher for widowed (4.9%) or separated/divorced (3.5%) than married (1.85%). The mean onset age was 50 years and the average number of lifetime episodes was 4.4. Only half of older adults with MDD had received treatment, even though one-fourth had thought about suicide. Anxiety disorder, substance dependence, and pathological gambling were highly associated with MDD.

CONCLUSION: Prevention could be targeted to older women and those who were widowed, separated, or divorced and low treatment rate was also alarming. More research is needed for the comorbid psychiatric disorders in late-life depression because of their impact on the course and prognosis of MDD.