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NIH study reveals incidence, precursors and psychiatric sequelae of major psychiatric disorders

April 23, 2008

A new study by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) presents results on the first onset of substance use disorders (i.e., alcohol and drug abuse and dependence) and major mood and anxiety disorders, based on Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).

This landmark survey is the first conducted in the U.S. to identify rates of first episodes (i.e., incidence) of these disorders in the U.S. population. In addition, it provides information on sociodemographic and psychopathologic risk factors for those disorders-information critical for developing evidence-based preventive interventions-and estimates risk for subsequent comorbid disorders.

Bridget Grant, Ph.D., Chief of NIAAA's Laboratory of Biometry and Epidemiology, and her colleagues found that 1-year incidence rates were highest for DSM-IV alcohol dependence (1.70%), alcohol abuse (1.02%), major depressive disorder (1.51%) and generalized anxiety disorder (1.12%), followed by panic disorder (0.62%), bipolar I disorder (0.53%) and specific phobia (0.44%). One-year incidence rates of DSM-IV social phobia (0.32%), bipolar II (0.21%) and drug abuse (0.28%) and drug dependence (0.32%) were lower but not insignificant. These rates are comparable to or exceed corresponding incidence rates for other common medical diseases such as lung cancer (0.06%), stroke (0.45%) and cardiovascular disease (1.5%).

The study found that men were at greater risk of first onset alcohol abuse, alcohol dependence and drug dependence, and 1-year incidence rates were greatest among 20- to 29-year-olds and individuals who had been separated/divorced/widowed or never married. By contrast, the risk of most incident DSM-IV anxiety disorders, including panic disorder, specific but not social phobia, and generalized anxiety disorder, was greatest among women, and all anxiety disorder incidence rates were greater in the youngest age groups (20- to 54-year-olds). Among DSM-IV mood disorders examined in this study, the risk of first onset of major depressive disorder (MDD) was greatest among women, and no sex differences in incidence were found for bipolar I and II disorders. Taken together, these results highlight age as an important general risk factor for first onset DSM-IV substance use, mood and anxiety disorders, whereas the effects of sex and marital status appear to be disorder-specific.

Consistent with earlier studies, baseline dysthymia in this study predicted incident MDD, and baseline MDD predicted incident bipolar II disorder, suggesting that MDD precedes hypomania in the development of bipolar II disorder. Consistent with other prospective studies, alcohol abuse and dependence showed strong reciprocal temporal relationships, whereas drug abuse predicted only incident drug dependence. "The reciprocal relationship between alcohol abuse and dependence suggests that strong common factors may underlie the relationship and provides support for eliminating the hierarchy between the disorders in future DSM revisions," state the authors. Other intriguing findings include reciprocal temporal relationships between MDD and GAD, and GAD and panic disorder, suggesting that common causes underlie those disorders. In addition, substance use disorders did not predict any incident mood or anxiety disorder, the authors note.

"Information on psychiatric risk factors prospectively identified in this study can begin to inform a new class of preventive interventions aimed at preventing a second disorder or set of disorders," said Grant. "As to clinical implications, this study helps to clarify the risk of future disorders posed by chronologically primary disorders, information that may be used to improve treatment planning and counsel patients at risk of developing secondary disorders."

Molecular Psychiatry