Continuous circular cycling ‘a distinct bipolar disorder subtype’

By Mark Cowen, Senior medwireNews Reporter

Results from an Italian study suggest that there are distinct differences in clinical presentation, outcome, and treatment response between bipolar disorder patients with and without intervals between mood episodes.

Indeed, in a study of 140 patients with bipolar I (n=77) or II disorder (n=63), the team found that those with a continuous circular course (CCC) of illness (without a free interval longer than 1 month between [hypo]manic and depressive episodes) were less than half as likely to achieve the primary outcome of no new episodes during follow up as those with a non-CCC.

"The results of the present study demonstrate the clinical, prognostic, and treatment value of distinguishing CCC and non-CCC pattern of course in bipolar disorders," comment Antonio Tundo (Istituto di Psicopatologia, Rome) and colleagues.

The patients, who were aged 18-65 years, attended the Istituto di Psicopatologia between 1998 and 2006 and received prophylactic treatment for at least 1 year. Overall, 28% of participants met criteria for bipolar disorder with a CCC.

On average, patients with a CCC were significantly older than non-CCC patients (45.7 vs 36.8 years), had an older age at onset of illness (32.0 vs 25.9 years), a higher total number of previous mood episodes (three vs one), and a higher number of previous depressive (two vs one) and (hypo)manic episodes (one vs none).

A significantly greater proportion of CCC than non-CCC patients had experienced switch (direct transitions from mania/hypomania to depression or vice versa), at 82.1% versus 16.8%, and they had also spent a significantly greater percentage of time ill in the year prior to enrolment, at 89.3% versus 65.8%.

Over the 1-year follow-up period after starting maintenance therapy, 37.6% of non-CCC patients remained episode-free compared with just 15.4% of CCC patients.

Tundo and team conclude in the Journal of Affective Disorders: "The presence or absence of… free intervals over the course of illness identifies two subtypes of bipolar disorder that differ in clinical presentation, outcome, and response to long-term treatment."

They add that "the present work contributes to better characterizing 'real world' patients with bipolar disorder."

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