Purpose: To examine the strength and specificity of the association between a manic episode and other common mental disorders at follow-up.
Background: Based on current evidence from twin studies demonstrating a genetic relationship between depression and generalized anxiety disorder (GAS), the likelihood of developing a depressive episode after a manic episode is expected to be similar to the likelihood of developing GAS. In contrast, the risk for developing other anxiety or substance use disorders should not be increased.
PATIENTS AND METHODS: A total of 43,093 participants were interviewed as part of the National Epidemiological Survey on Alcohol and Related Conditions (NESARC). Both 12-month and lifetime prevalence for mental disorders were assessed using DSM IV criteria. In a follow-up after three years, there was rescreening with a responder rate of 86.7%. Adjusted logistic regressions were used to determine odds ratios, with analyses controlling for sociodemographic variables and health-related quality of life.
Results: Mania at baseline (T1) was significantly associated with increased odds for major depression at follow-up (T2) and with all anxiety disorders (except social phobia). Here, the likelihood of patients with mania at T1 developing a substance use disorder at T2 was not significantly different from that of patients who did not have mania at that time. Major depression at time T1 was associated with a significantly increased likelihood of developing (hypo)mania and all anxiety disorders at time T2. However, the odds for substance use disorders at time T2 were not significant.
Authors’ conclusions: The results of this study are consistent with the assumptions regarding a genetic relationship between depression and anxiety disorders. It is possible that anxiety symptomatology in adults with a history of a manic episode is an expression of the same clinical syndrome. Further studies should examine whether mania and anxiety disorders share common gene/environmental risk factors. Regarding psychiatric nosology, it needs to be reevaluated whether the prospective association between mania and depression, which is relevant for making the clinical diagnosis, should be extended to include anxiety symptomatology. Alternatively, (hypo)mania could be considered an independent entity with an increased likelihood of being comorbid with depression and anxiety disorder.
Comment: In view of the presented study results as well as the current findings on the (epi-)genetic factors and biomarkers of mental disorders, it can be assumed that a new era in the classification of mental disorders is on the horizon, mainly characterized by genome-wide associations and overlapping risks. As a consequence, this is likely to bring not only new treatment options (e.g., pharmacogenetics) but also a rethinking of etiological assumptions about common mental disorders.
InFo NEUROLOGY & PSYCHIATRY 2016; 14(5): 34.
