Given the success of cognitive models of unipolar depression in elucidating important cognitive processes in the onset, course, and treatment of depression, there has been much interest in applying these models to bipolar spectrum disorders. However, the evidence for the occurrence of negative cognitive styles independent of current mood state in individuals with bipolar disorders and the role of such cognitive patterns in predicting mood symptoms and episodes in the course of bipolar disorder is mixed (Alloy et al., 2005
; Cuellar et al., 2005
). The present study was designed to examine whether the concurrent and prospective associations between cognitive styles and bipolar spectrum disorders would be more consistent for a subset of cognitive styles that are BAS-relevant.
Based on a BAS dysregulation model of bipolar disorders (e.g., Alloy et al., 2008
; in press
; Depue & Iacono, 1989
; Depue et al., 1987
; Johnson, 2005
; Urosevic et al., 2008a
), we hypothesized that individuals with bipolar spectrum disorders would differ from normal control individuals on BAS-relevant, but not non-BAS-relevant cognitive styles, and that the group differences on BAS-relevant styles would at least partially mediate group differences in BAS sensitivity. The findings were supportive of the first, and partially supportive of the second, hypothesis. As expected, the correlations between diagnostic group and the BAS-relevant cognitive styles were significantly greater than the correlations between diagnostic group and the non-BAS-relevant styles from the same measures. Moreover, controlling for concurrent levels of depressive and hypomanic/manic symptoms, bipolar participants exhibited significantly higher scores than controls on the BAS-relevant cognitive dimensions of performance evaluation (DAS), autonomy (SAS), and self-criticism (DEQ). However, they did not differ from controls on the non-BAS-relevant dimensions of approval by others (DAS), sociotropy (SAS), and dependency (DEQ). That the associations between bipolar status and elevated scores on BAS-relevant cognitive dimensions held despite controlling for concurrent depressive and hypomanic/manic symptoms suggests that symptomatic state is unlikely to provide a plausible explanation for the group differences. Indeed, higher state levels of hypomanic symptoms (HMI) were associated with higher autonomy and lower need for approval by others, sociotropy, and dependency. In contrast, with state hypomanic symptoms controlled, a tendency to experience recurrent hypomania/mania as reflected in a bipolar diagnosis was not associated with lower scores on the BAS-irrelevant dimensions of approval by others, sociotropy, and dependency.
In addition, our findings are consistent with several other studies that also have reported that individuals with disorders in the bipolar spectrum only exhibit dysfunctional cognitive patterns with BAS-relevant features (Goldberg et al., 2008
; Lam et al., 2004
; Rosenfarb et al., 1988
; Scott et al., 2000
; Wright et al., 2005
). Thus, individuals with bipolar disorders may exhibit a unique profile of cognitive styles consistent with the goal-striving, drive, and incentive motivation associated with high BAS sensitivity (Alloy et al., 2005
; Johnson, 2005
), but not dependency, approval-seeking, and attachment attitudes typically observed among individuals with unipolar depression (Zuroff et al., 2004
). Interestingly, and consistent with the past unipolar depression findings, we did observe that higher state levels of depressive symptoms (BDI) were associated significantly with higher scores on all of the cognitive style dimensions except SAS autonomy.
Moreover, our findings also go beyond prior research on BAS-relevant cognitive styles in bipolar disorder by examining whether individuals’ BAS-related cognitive styles mediated their elevated scores on BAS sensitivity. Consistent with the mediation hypothesis, bipolar spectrum participants scored higher on self-reported BAS sensitivity (Total, Drive and Fun-Seeking) than the controls and higher BAS sensitivity was significantly associated with elevated scores on the three BAS-relevant cognitive styles that differentiated the bipolar and control groups (DAS performance evaluation, SAS autonomy, and DEQ self-criticism). In addition, we found that autonomy fully mediated the association between bipolar status and BAS sensitivity. In contrast, although performance evaluation and self-criticism continued to be significantly associated with bipolar status controlling for BAS sensitivity, neither mediated the bipolar status - BAS sensitivity association. Although these findings are cross-sectional and not able to demonstrate causal relationships, they are consistent with the idea that high BAS sensitivity contributes to the development of an autonomous cognitive style, which, in turn, may contribute risk for bipolar disorder. Whereas high BAS sensitivity may also contribute to self-critical and perfectionistic cognitive styles and these styles are related to bipolar status, they did not seem to provide a mechanism by which BAS sensitivity is associated with bipolarity (at least as measured here).
We also evaluated whether BAS-related cognitive styles were more likely than non-BAS-relevant styles to predict the onset of mood episodes among bipolar spectrum participants during a 3.2-year prospective follow-up and whether BAS-relevant cognitive styles mediated predictive associations between BAS sensitivity and prospective mood episodes. Consistent with hypothesis, some of the BAS-related cognitive styles predicted significantly the likelihood of onset of major depressive and hypomanic/manic episodes, controlling for initial levels of depressive and hypomanic/manic symptoms and past history of mood episodes. None of the non-BAS-related cognitive dimensions predicted mood episode onsets in our bipolar sample. Whereas higher levels of self-criticism and autonomy predicted a greater likelihood of hypomanic/manic episode onset, higher autonomy was associated with a smaller likelihood of major depressive episode onset. Again, the fact that some BAS-related cognitive dimensions predicted the likelihood of mood episode onset prospectively controlling for initial symptom levels and past history of mood episodes suggests that the prospective associations between BAS-relevant cognitive styles and mood episodes are not readily attributable to residual symptoms or scarring by past episodes associated with elevated cognitive styles. However, it should be noted that the associations between autonomy and self-criticism and prospective mood episode onsets were small to moderate in magnitude. It may be that these BAS-relevant cognitive styles would have greater predictive power for bipolar mood episode onsets in combination with BAS-relevant life events (see Alloy et al., in press
; Urosevic et al., 2008
It is interesting that SAS autonomy predicted a greater likelihood of hypomanic/manic episodes, but a smaller likelihood of major depressive episodes. This particular finding raises the intriguing possibility that some BAS-relevant cognitive styles may not always be maladaptive. Research suggests that bipolar disorder is characterized by both high levels of impairment and achievement (see Nusslock et al., 2008
). Thus, an important question is what psychological traits or mechanisms are associated with achievement among individuals with bipolar spectrum disorders. It is possible that some BAS-related cognitive styles, such as high autonomy, also contribute to BAS-mediated adaptive outcomes such as positive goal striving and achievement. Future research needs to test this speculation.
Although autonomy and self-criticism predicted the likelihood of mood episode onsets prospectively, only autonomy mediated the predictive association between BAS sensitivity and prospective hypomanic/manic episodes. Indeed, self-criticism no longer predicted hypomania/mania with BAS sensitivity controlled. Thus, autonomy mediated the associations between BAS sensitivity and both bipolar diagnosis (cross-sectional analyses) and hypomania/mania onset (prospective analyses). The prospective mediation findings for autonomy are particularly noteworthy because prospective data allow for a stronger test of mediation than do cross-sectional analyses. These prospective findings for autonomy provide further support for the idea that high BAS sensitivity may contribute to the development of an autonomous cognitive style, which, in turn, increases risk for bipolar disorder and hypomanic/manic episodes. Given that an autonomous cognitive style as measured by the SAS involves an emphasis on individualistic achievement, this finding is consistent with Lozano and Johnson’s (2001)
report that an achievement-striving style predicted manic symptoms in a 6-month follow-up of bipolar I patients. Moreover, our results suggest that an autonomous cognitive style mediates the effects of a temperament characterized by high drive and incentive motivation on bipolarity.
Study Strengths and Limitations
This investigation has several strengths. These include the inclusion of a large sample of individuals with bipolar spectrum disorders and demographically similar normal controls, the use of standardized diagnostic interviews and criteria, interviewers blinded to cognitive style and BIS/BAS scores, a prospective longitudinal design, conservative statistical tests of the study hypotheses, and an examination of whether elevated BAS sensitivity among bipolar individuals is mediated by BAS-relevant cognitive styles.
However, it is important to recognize this investigation’s limitations as well. First, the study sample consisted of undergraduates, which although ethnically and socioeconomically diverse, may not be representative of community or clinical samples. Replication of our findings in a community sample with bipolar spectrum disorders and in samples with more severe bipolar I disorder is important. However, bipolar II and cyclothymia tend to be understudied relative to bipolar I disorder, and are often risk factors for the progression to bipolar I disorder (e.g., Shen et al., 2008
), suggesting the value of the present study as well. Second, cognitive styles were assessed with self-report instruments only. Although the self-report measures chosen for this study are reliable and valid assessments of cognitive style, future tests of associations between BAS-related cognition and bipolar disorder may benefit from use of task-based measures of cognition as well. Similarly, although the BIS/BAS Scales have been validated against behavioral (Zinbarg & Mohlman, 1998
) and neurobiological (Harmon-Jones & Allen, 1997
; Sutton & Davidson, 1997
) indices of BAS sensitivity, future studies of the relationship between cognitive styles and BAS sensitivity would also benefit from use of multiple indicators of BAS (e.g., EEG).