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Homotypic, heterotypic risk factors may help predict bipolar disorder onset

Early patterns of homotypic and heterotypic psychopathological symptoms, along with behavior changes and environmental factors, were significantly associated with later diagnoses of bipolar disorder, according to research findings.

“Recent worldwide estimates of lifetime prevalence of [bipolar disorder] in the general population average 2.4%, plus an additional 2.4% experiencing subthreshold forms of [bipolar disorder] not meeting standard diagnostic criteria,” Ciro Marangoni, MD, from the department of mental health at Mater Salutis Hospital in Italy, and colleagues wrote in Harvard Review of Psychiatry. “Younger onset is associated with a greater likelihood of familial mood disorder and also with a less favorable clinical course, more co-occurring anxiety and substance abuse, more recurrences that include rapid cycling ( 4 episodes in 1 year), inferior response to treatment, and more hospitalizations, disability, and suicidal behavior.

Using clinical databases, researchers reviewed 39 prospective, observational and case-control studies that discussed the onset of bipolar disorder and factors that have been identified as predicting its onset. They included studies of patients with bipolar disorder, but who were not diagnosed at initial assessment, and studies that included new diagnosis of bipolar disorder as the reported outcome. Findings from these studies were qualitatively summarized.

Consistent with research from prospective studies, the researchers found that affective psychopathology usually precedes diagnosis to suggest a homotypic pattern in developing bipolar disorder, and early heterotypic patterns of psychopathological disturbances — such as anxiety and disruptive behavior disorders — along with environmental factors and exposures increase the risk for bipolar disorder, but often lack specificity in predicting the disorder. Although homotypic symptoms have low sensitivity, this symptom pattern showed moderate to high specificity, according to the researchers. On the other hand, the heterotypic pattern had low sensitivity and specificity, meaning only some patients with such symptoms develop bipolar depression. This evidence suggests that a wide range of psychopathological symptoms, behavioral changes and exposures are associated with later diagnoses of bipolar disorder.

“The predictive value of heterotypic risk factors appears to be less than for homotypic factors. In order to enhance the prognostic value of clinical features that can predict later diagnosis of [bipolar disorder], it may be necessary to combine multiple risk factors rather than to focus on single predictors,” Marangoni and colleagues wrote. “It also remains to be explored whether different features or clusters of factors may have specific predictive value for particular aspects of [bipolar disorder], such as bipolar subtype, overall severity, course patterns, predominant polarity, treatment response, disability, suicide, and mortality risks.” – by Savannah Demko

Disclosures: The authors report no relevant financial disclosures.