Findings from the largest survey ever conducted on the co-occurrence of psychiatric disorders among U.S. adults indicates a sharper picture than previously reported of major depressive disorder (MDD) in specific population groups.
Results from the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC) also indicate a strong relationship of MDD to alcohol use disorders, drug disorders and other mental health conditions.
According to researchers at Columbia University's Mailman School of Public Health, middle age, female gender, Native American race, low income, and separation, divorce, or widowhood increase the likelihood of current or lifetime MDD. "Elevated rates of major depression in baby boomers and in Native Americans were among the most striking findings to emerge from the study," said Deborah Hasin, PhD, professor of clinical Epidemiology at the Mailman School and lead author of the paper. The latest data also indicates that Asian, Hispanic, and black race-ethnicity reduce that risk.
The NESARC involved face-to-face interviews with more than 43,000 non-institutionalized individuals aged 18 years and older and questions that reflect diagnostic criteria established by the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders. Findings conclude that five percent of U.S. adults experienced MDD during the 12 months preceding the survey and 13 percent experienced MDD at any time during their lives. Notable is that the highest lifetime risk was among middle-aged adults, a shift from the younger adult population shown to be at highest risk by surveys conducted during the 1980s and 1990s. "This marks an important transformation in the distribution of MDD in the general population and specific risk for baby-boomers aged 45 to 64 years," remarked Dr. Hasin.
Risk for the onset of MDD increases sharply between age 12 and age 16 and more gradually up to the early 40s when it begins to decline, with mean age of onset about age 30. Women are twice as likely as men to experience MDD and somewhat more likely to receive treatment. About 60 percent of persons with MDD received treatment specifically for the disorder, with mean treatment age at 33.5 years--a lag time of about three years between onset and treatment. Of all persons who experienced MDD, nearly one-half wanted to die, one-third considered suicide, and nine percent reported a suicide attempt.
Among those with current MDD, 14 percent also have an alcohol use disorder, five percent have a drug use disorder, and 26 percent have nicotine dependence. More than 37 percent have a personality disorder and more than 36 percent have at least one anxiety disorder.
The NESARC results demonstrate a strong relationship of MDD to substance dependence and a weak relationship to substance abuse, a finding that indicates the importance of focusing on dependence when studying the relationship of depression to substance use disorders. This is supported by an earlier epidemiologic study conducted by Dr. Hasin and Mailman School colleague Renee Goodwin, PhD, assistant professor of Epidemiology, showing a four-fold increase in risk of current MDD among long-abstinent former alcoholics, and studies that identified genetic factors common to MDD and alcohol dependence.
The NESARC also found strong relationships between MDD and anxiety disorders. In addition, MDD was strongly associated with personality disorders, but the magnitude of the association varied considerably between the different personality disorder types. "Given the seriousness of MDD, the importance of information on its prevalence, demographic correlates, and psychiatric comorbidity cannot be overstated," notes Dr. Goodwin. "This study provides the grounds for further investigation in a number of areas."