Research report
Impulsivity: Differential relationship to depression and mania in bipolar disorder

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Abstract

Introduction

Impulsivity, a component of the initiation of action, may have a central role in the clinical biology of affective disorders. Impulsivity appears clearly to be related to mania. Despite its relationship to suicidal behavior, relationships between impulsivity and depression have been studied less than those with mania. Impulsivity is a complex construct, and it may be related differently to depression and to mania.

Methods

In subjects with bipolar disorder, we investigated impulsivity in relationship to affective symptoms. Trait-like impulsivity was assessed with the Barratt Impulsiveness Scale (BIS-11). Affective symptoms were measured using the Change version of the Schedule for Affective Disorders and Schizophrenia (SADS-C). Measures were compared using analysis of variance, multiple regression and factor analysis.

Results

Impulsivity, as measured by the BIS, was related differentially to measures of depression and mania. Total and attentional impulsivity correlated independently with depression and mania scores. Motor impulsivity correlated with mania scores, while nonplanning impulsivity correlated with depression scores. These relationships were strongest in subjects who had never met criteria for a substance use disorder. Among manic symptoms, visible hyperactivity correlated most strongly with BIS scores, regardless of clinical state. Among depressive symptoms, hopelessness, anhedonia, and suicidality correlated most strongly with BIS scores.

Conclusions

Depression and mania are differentially related to impulsivity. Impulsivity is related more strongly to measures of activity or motivation than to depressive or manic affect. The relationship between impulsivity and hopelessness may be an important factor in risk for suicide.

Introduction

Impulsivity is related to mechanisms and consequences of affective symptoms. Its relationship to mechanism stems from its role in the initiation of action (Barratt and Patton, 1983, Moeller et al., 2001). Impulsivity can be regarded as a predisposition to action without reflection or regard for consequences (Moeller et al., 2001). Consequences of impulsivity include substance abuse (Moeller et al., 2002, Swann et al., 2004), suicidal behavior (Maser et al., 2002, Simon et al., 2001, Swann et al., 2005), and other serious behavioral problems (Stanford and Barratt, 1992).

There is little information about impulsivity and specific affective symptoms. Impulsivity is considered to be inherent in mania and is a prominent part of its diagnostic criteria (First et al., 1996, Swann et al., 2001b). Impulsivity is complex, however, and specific relationships between manic symptoms and specific aspects of impulsivity have not been investigated.

In the case of depression, there is even less information. At first glance, depression may appear less strongly related to impulsivity than mania is. Combinations of depression and impulsivity are important in suicidal behavior (Soloff et al., 2000), but impulsivity in this situation may be related to manic symptoms (Swann et al., 2007). Interestingly, an epidemiological study found impulsive suicide attempts to be associated with high Beck Hopelessness Scale scores but with low depression scores (Simon et al., 2001). One aspect of impulsivity, as measured by the Barratt Impulsiveness Scale, is nonplanning impulsivity, or lack of sense of the future (Patton et al., 1995). This aspect of impulsivity may be related to hopelessness and depression.

We have investigated relationships between specific aspects of impulsivity and affective symptoms in subjects with bipolar disorder who were depressed, manic, or not experiencing a current episode. The self-rated Barratt Impulsiveness Scale has been extensively validated and provides an integrated measure of impulsivity. Its three subscales measure cognitive, behavioral, and adaptive aspects of impulsivity (Patton et al., 1995). Our hypotheses were that depression and mania would be differentially related to impulsivity, and that the strongest relationships would involve symptoms related to activation, rather than mood.

Section snippets

Subjects

Potential subjects, who were referred to the study by clinicians or who responded to advertisements that had been approved by the Institutional Review Board, were fully informed of the procedures, risks, and benefits of the study, and signed informed consent documents, before any study-related procedures took place. The study was approved by the Committee for the Protection of Human Subjects, the Institutional Review Board (IRB) for the University of Texas Health Science Center at Houston. All

Impulsivity and affective state

Interepisode subjects had mean SADS-C mania rating scale (MRS) score of 5.7 ± 4.6 (SD) and depression score of 7.9 ± 4.8; for manic subjects, MRS was 18.9 ± 6.7 and depression 8.7 ± 4.9; for depressed subjects, MRS was 4.6 ± 4.9 and depression 24.6 ± 4.9, and for mixed states, MRS was 17.9 ± 7.9 and depression score was 22.4 ± 7.3. Depression and mania scores did not correlate significantly (r =  0.09, p > 0.4). As shown in Table 1, BIS scores were increased in depressed, manic, and mixed, compared to

Definitions and components of impulsivity

Impulsivity defines behavior that occurs without the opportunity for reflection and is therefore not consistent with its context (Moeller et al., 2001). The BIS-11 identifies three components of impulsivity. Attentional/cognitive impulsivity is a lack of cognitive persistence with inability to tolerate cognitive complexity; motor impulsivity is a tendency to act on the spur of the moment; and nonplanning impulsivity refers to a lack of sense of the future (Patton et al., 1995).

The data in this

Conclusions

Impulsivity appears differentially related to depressive and manic symptoms. Attentional-cognitive impulsivity is increased with either depression or mania; motor impulsivity correlates with mania, and nonplanning impulsivity with depression. Impulsivity correlated most strongly with hyperactivity in mania and with hopelessness or anhedonia in depression, reflecting the possibility of a stronger relationship to motivation or activity than to subjective affect.

Role of the funding source

This work was supported by the Pat R. Rutherford, Jr. Chair in Psychiatry (ACS) and by NIH grants RO1 MH 69944 (ACS; principal source of funding), RO1 DA 08425 (FGM), and KO2 DA 00403 (FGM). The funding sources were not involved in design of the studies, analysis or interpretation of the data, preparation of the manuscript, or decision to publish the manuscript.

Disclosure of potential conflicts of interest

ACS: grant support: Bristol Myers Squibb, Novartis, Shire Labs Consultant or advisory board: Abbott Laboratories, Astra Zeneca, Bristol Myers Squibb, Cyberonics, Glaxo SmithKline, Novartis, Ortho McNeill, Pfizer, Shire Labs Speakers bureau or sponsored lectures: Abbott laboratories, Astra Zeneca, Glaxo SmithKline.

  • JLS: None

  • ML: None

  • FGM: grant support: Ortho McNeill

Acknowledgements

This study was supported in part by the Pat R. Rutherford, Jr. Chair in Psychiatry (ACS) and by NIH grants RO1 MH 69944 (ACS), RO1 DA08425 (FGM), and KO2 DA00403 (FGM). We thank Saba Abutaseh, Glen Colton, Psy.D., Stacey Meier, and Mary Pham for their assistance.

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    This study was supported in part by the Pat R. Rutherford, Jr. Chair in Psychiatry (ACS) and by NIH grants RO1 MH 69944 (ACS), RO1 DA08425 (FGM), and KO2 DA00403 (FGM). We thank Saba Abutaseh, Glen Colton, Psy.D., Stacey Meier, and Mary Pham for their assistance.

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