By Mark Cowen
A wide range of demographic, clinical, and environmental factors are associated with an increased risk for transition from major depressive disorder (MDD) to bipolar disorder (BD), US study results show.
Such risk factors include lower levels of education, younger age, prior psychopathology, and a history of child abuse, report Stephen Gilman (Harvard School of Public Health, Boston, Massachusetts) and team.
Interestingly, clinical characteristics of depression were not associated with diagnostic conversion.
The findings come from a 3-year follow-up of 6214 patients initially diagnosed with MDD who participated in the National Epidemiologic Survey on Alcohol and Related Conditions.
During the follow-up period, 245 (4.0%) MDD patients made the transition to BD, defined as experiencing a first manic episode according to DSM-IV criteria.
Logistic regression analysis revealed that demographic factors associated with an increased risk for transition to BD included younger age at study entry, at an odds ratio (OR) of 5.58 for individuals aged 18-29 years versus those older than 60 years, Black race, at an OR of 1.59 versus White individuals, and failure to complete high school, at an OR of 1.95.
Clinical factors associated with an increased risk for transition included a history of panic disorder (OR=1.53), social phobia (OR=2.20), and generalized anxiety disorder (OR=1.58), but other clinical factors, such as younger age at MDD onset and the presence of atypical features, were not.
The researchers also found that a history of childhood abuse was associated with an increased risk for transition, at an OR of 1.26, as were stressful situations in the past year, including social support group problems (OR=1.79) and economic problems (OR=1.45).
However, receiver operating characteristic (ROC) analysis showed that a combination of these risk factors had only modest predictive power for transition, with an area under the ROC curve of 72.4%.
This, say the researchers, indicates "better-than-chance prediction, but not sufficiently high for use as a clinical screening tool for the future development of bipolar disorder among lifetime cases of MDD."
Gilman et al conclude in the Journal of Clinical Psychiatry: "Additional work is needed to further enhance the prediction of bipolar disorder among cases of MDD and to determine whether interventions targeting these factors could reduce the risk of bipolar disorder."
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