BD family history risk factor for recurrent episodes in MDD

By Ingrid Grasmo, medwireNews Reporter

A family history of bipolar disorder increases the likelihood of recurrent episodes of hypomania or mania (H/M) in individuals with prior major depressive disorder, suggest findings published in Bipolar Disorders.

The research also shows that these patients have a lower risk for subsequent H/M if the first episode occurred within 8 weeks of initiating an antidepressant or electroconvulsive therapy (ECT).

Discussing the proposed revisions for DSM-V, Jess Fiedorowicz (University of Iowa, USA) and colleagues say the findings "do not support the predictive validity of treatment-associated mania and also fail to support the proposed relevance of an H/M episode 'persisting beyond the physiological effect of that treatment.' "

However, the findings offer some support to practitioners who distinguish treatment-associated hypomania as a distinct disorder on the bipolar spectrum.

This prospective study of 108 patients diagnosed with unipolar major depression at intake found 21 of 60 patients who developed H/M had a family history of bipolar disorder. Indeed, a family history of the mood disorder was associated with a two-fold increased likelihood of repeat episodes of H/M.

The researchers say this is consistent with previous study findings showing that individuals with bipolar disorder and a family history of the condition have more episodes than those without this genetic predisposition.

Twelve patients developed H/M within 8 weeks of starting to take an antidepressant or undergoing ECT, of whom 33% reached the threshold for mania while the remainder had only hypomania. Furthermore, only 27% of the 96 patients with spontaneous episodes met the criteria for mania.

The study also showed that compared with 60% of patients with a spontaneous episode, only 17% with treatment-associated H/M developed a subsequent H/M. Notably, patients with treatment-associated H/M had a significantly later age of onset for mood disorder and were more likely to have been experiencing depressive symptoms in the 8 weeks prior to the index H/M episode.

The authors say it remains unclear whether the findings reflect true differences between a hypothetical population vulnerable to antidepressant-associated H/M and those prone to spontaneous H/M.

They call for a prospective study of mood disorders to resolve nosological issues concerning the position of antidepressant-associated H/M. "Nonetheless, our data suggest that duration of H/M in weeks does not have any predictive validity, nor do specific thresholds of 2 or 4 or more weeks," add the researchers.

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