Impulsivity differences between bipolar and unipolar depression

Even though particularly bipolar depression and unipolar depression seem to be similar, they show differences in terms of the etiology, phenomenology, course, and treatment process. Bipolar depression is associated with mood lability, motor retardation, and hypersomnia to a larger extent. Early age of onset, a high frequency of depressive episodes, and history of bipolar disease in the family are suggestive of bipolar disorder (BD) rather than major depression. Bipolar and unipolar disorders are also associated with increased impulsivity during illness episodes. However, there is little information about impulsivity during euthymia in these mood disorders. The aim of this study was to illustrate the difference in impulsivity in euthymic bipolar and unipolar patients.

Impulsivity was evaluated by the Barratt Impulsiveness Scale (BIS-11A), in 78 interepisode BD patients, 72 interepisode unipolar disorder patients, and 70 healthy controls. The diagnosis was established by severe combined immunodeficiency. One-way between-groups ANOVA was used to compare the BIS-11A mean scores for all three groups.

Impulsivity scores of the bipolar and unipolar disorder patients were significantly higher than controls on total and all subscales measures. There was no difference between the bipolar and unipolar disorder groups on total, attentional, and nonplanning impulsivity measures. However, BD patients scored significantly higher than the unipolar patients on motor impulsivity measures.

Both interepisode bipolar and unipolar disorder patients had increased impulsivity compared to healthy individuals. There was no significant difference on attention and nonplanning impulsivity subscales; however, on the motor subscale, bipolar patients were more impulsive than unipolar disorder patients.