The functioning of the Behavioral Activation and Inhibition Systems in bipolar I euthymic patients and its influence in subsequent episodes over an eighteen-month period

In order to better understand individual vulnerabilities to bipolar I disorder, this study evaluates individual differences in Behavioral Activation and Inhibition Systems as possible markers of bipolar I disorder. BAS and BIS functioning was evaluated in 39 bipolar I euthymic patients and in 38 controls. Patients showed higher scores on the BAS scale; differences were not detected on the BIS scale. Eighteen months post-initial assessment, patients were re-grouped according to the presence and type of new episodes. Patients relapsing with a depressive episode showed lower scores on the BAS scale than patients suffering from a manic/hypomanic episode, and a tendency to score lower than patients still asymptomatic. Reported higher BAS functioning would reinforce the hypothesis of a trait vulnerability to present approach behaviors during euthymia associated with bipolar I disorder, not necessarily related to the proximity of a manic/hypomanic episode, and interestingly not detected when approaching a depressive episode, circumstance in which BAS functioning would be similar to controls. Results did not reveal a weaker BIS in patients, hypothesized to account for BAS instability in bipolar I disorder.