Sharper picture than previously available of major depressive disorder

Findings from the largest survey ever mounted on the co-occurrence of psychiatric disorders among U.S. adults afford a sharper picture than previously available of major depressive disorder (MDD) in specific population subgroups and of MDD's relationship to alcohol use disorders (AUDs) and other mental health conditions.

The new analysis of data from the 2001-2002 National Epidemiologic Survey of Alcohol and Related Conditions (NESARC) shows for the first time that middle age and Native American race increase the likelihood of current or lifetime MDD, along with female gender, low income, and separation, divorce, or widowhood. Asian, Hispanic, and black race-ethnicity reduce that risk. Conducted by the NIH's National Institute on Alcohol Abuse and Alcoholism (NIAAA), the analysis appears in the October 3, 2005 Archives of General Psychiatry.

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 (DSM-IV). Its principal foci were alcohol dependence (alcoholism) and alcohol abuse and the psychiatric conditions that most frequently co-occur with those AUDs. Because of its size and scrutiny of multiple sociodemographic factors, the NESARC provides more precise information than previously available on between-group differences that influence risk.

For example, the analysis indicates that 5.28 percent of U.S. adults experienced MDD during the 12 months preceding the survey and 13.23 percent had experienced MDD at some time during their lives. 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," note the authors.

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 3 years between onset and treatment. Of all persons who experienced MDD, nearly one-half wanted to die, one-third considered suicide, and 8.8 percent reported a suicide attempt.

Among race-ethnic groups, Native Americans showed the highest (19.17 percent) lifetime MDD prevalence, followed by whites (14.58 percent), Hispanics (9.64 percent), Blacks (8.93 percent), and Asian or Pacific Islanders (8.77 percent). Since information is scarce on diagnosed mental disorders among Native Americans, this finding appears to warrant increased attention to the mental health needs of that group, the authors maintain.

Among persons with current MDD, 14.1 percent also have an AUD, 4.6 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. Among persons with lifetime MDD, 40.3 percent had experienced an AUD, 17.2 percent had experienced a drug use disorder, and 30 percent had experienced nicotine dependence.

"Major depression is a prevalent psychiatric disorder and a pressing public health problem. That it so often accompanies alcohol dependence raises questions about when and how to treat each diagnosis," says NIAAA Director Ting-Kai Li, M.D. "Today's results both inform clinical practice and provide researchers with information to advance hypotheses about common biobehavioral factors that may underlie both conditions."

The NESARC results demonstrate a strong relationship of MDD to substance dependence and a weak relationship to substance abuse, a finding that suggests focusing on dependence when studying the relationship of depression to substance use disorders. This research direction is supported by earlier genetic studies that identified factors common to MDD and alcohol dependence and at least one epidemiologic study that demonstrated excess MDD among long-abstinent former alcoholics, state the authors.

Coexisting substance dependence disorder and MDD predict poor outcome among clinic patients. A decade ago, many treatment leaders discouraged treating MDD in patients with substance dependence on the grounds that arresting substance dependence was the more immediate need and that its resolution well might also resolve MDD. Results from foregoing epidemiologic surveys and several clinical trials over time altered that picture, so that treating both disorders simultaneously is today common practice.

The NESARC also found strong relationships between MDD and anxiety disorders, with the strongest comorbidity for current diagnoses. In addition, MDD was strongly associated with personality disorders, but the magnitude of the association varied considerably among discrete personality disorder types. "Given the seriousness of MDD, the importance of information on its prevalence, demographic correlates, and psychiatric comorbidity cannot be overstated," note the authors. "This study provides the grounds for further investigation in a number of areas."

The Epidemiology of Major Depressive Disorder by principal investigator Bridget F. Grant, Ph.D., Chief, Laboratory of Epidemiology and Biometry, NIAAA, in collaboration with Deborah S. Hasin, Ph.D., of Columbia University and New York State Psychiatric Institute and their coauthors is available online to journalists at www.jamamedia.org. For interviews with Dr. Grant, please contact the NIAAA Press Office.

The NESARC data set, interview, descriptive materials, and citations are available at http://niaaa.census.gov/. News releases based on NESARC data and additional alcohol research information and publications are available at www.niaaa.nih.gov.