Impulse control predicts euthymia in bipolar disorder

By Lucy Piper, Senior medwireNews Reporter

Patients with bipolar disorder who have good trait impulse control are likely to respond better to treatment than those with poor impulse control, say researchers.

“We found that better self-reported impulse control was the primary predictor of time to reach euthymia when compared to other clinical characteristics associated with disease course,” the researchers write in Bipolar Disorders.

They recommend that treatment providers consider targeting impulse control as a potential protective factor among adults with bipolar I disorder.

Assessment of 94 participants hospitalised with bipolar I disorder showed that better self-reported impulse control on the Barratt Impulsiveness scale 11th edition (BIS-11) significantly correlated with greater educational attainment, later age at illness onset, shorter illness duration and fewer depressive symptoms.

And patients with good impulse control were less likely than those without to have comorbid psychiatric conditions associated with poorer treatment outcomes, such as a lifetime history of alcohol or drug misuse, or attention-deficit hyperactivity disorder.

A total of 26 patients reached euthymia within 8 months of hospitalisation and the likelihood of this outcome was significantly increased if patients had lower baseline Montgomery–Åsberg Depression Rating Scale scores, lower BIS-11 scores, shorter illness duration and did not have a lifetime history of marijuana misuse.

When these variables were entered into a logistic regression model predicting achievement of euthymia, the area under the receiver operating characteristic (ROC) curve was 0.71, which meets the customary criterion for diagnostic utility of 0.70.

But of the individual variables, only BIS-11 baseline score had an odds ratio significant enough to be able to discriminate between participants who did and did not achieve euthymia, the researchers report.

Similarly, only BIS-11 score was found to be a significant unique predictor in cox regression models predicting time to reach euthymia from a collection of demographic, clinical and test variables.

Researcher Paula Shear (University of Cincinnati, Ohio, USA) and colleagues note that while good self-reported trait impulse control shortened the time to reach euthymia, behavioural impulsivity had no effect.

“This finding supports previous results indicating that impulsivity measures often do not correlate with one another and may therefore measure separate subcomponents of impulse control”, they say.

The researchers conclude that determining “whether better trait impulse control is associated with a less severe disease course versus better responsiveness to typical treatments represents an interesting avenue for future research and may help to guide future treatment planning in this population.”

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