Publication Date

2012-10-08

Availability

Embargoed

Embargo Period

2014-10-08

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Psychology (Arts and Sciences)

Date of Defense

2012-10-03

First Committee Member

Charles S. Carver

Second Committee Member

Amy Weisman de Mamani

Third Committee Member

Matthias Siemer

Fourth Committee Member

Ihsan Salloum

Fifth Committee Member

Sheri L. Johnson

Abstract

Impulsivity as a symptom during mania is well documented, but less is known about the driving factors behind these impulsive acts. Perhaps this is because impulsivity is a term that encompasses multiple facets. There is evidence for a type of impulsivity in which extreme sensitivity to positive affective states can influence cognitive processes, such as error detection and identification of threatening cues. This can ultimately lead to engagement in impulsive actions during elevated mood states. Among people who are vulnerable to mania, positive moods have larger or more pervasive effects than they have on other people. While there is more conclusive evidence of impulsiveness among persons with BD (Bipolar Disorder) during mania, as compared to euthymia, it is less clear what specific mechanisms or mania symptoms perpetuate this effect. This study examined the possibility that positive emotion creates a greater processing bias among persons with BD than among other persons, such that neutral and negative stimuli are perceived less negatively. This study utilized multiple methods to measure the emotional response to threat--the motivational component with measurement of the affect-modulated eyeblink startle response, the arousal component with measurement of skin conductance levels, and the explicit appraisal component of emotional experience with self-report mood ratings. Twenty-two participants with BD and 25 control participants viewed a series of valenced pictures (negative, positive, neutral), underwent a cognitive speed task to induce a positive mood, and then viewed another series of valenced pictures. Acoustic startle probes were paired with the pictures at 2500ms and 4500ms. Skin conductance tonic levels, eyeblink startle amplitude, and eyeblink latency times were measured continuously through the laboratory session. BD participants had lower SCL tonic levels to the negative stimuli after the mood induction, compared to control participants. There was no group difference in eyeblink amplitude or in eyeblink latency. Several limitations, including issues with study methodology, recruitment bias, and validity of the IAPS stimuli, were reviewed. Future directions for research and clinical implications were discussed.

Keywords

bipolar disorder; impulsivity; startle reflex; positive mood

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