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Sensorimotor gating in manic and mixed episode bipolar disorder

Authors

  • Christine A Carroll,

    1. Department of Psychological and Brain Sciences, Indiana University, Bloomington
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  • Jenifer L Vohs,

    1. Department of Psychological and Brain Sciences, Indiana University, Bloomington
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  • Brian F O'Donnell,

    1. Department of Psychological and Brain Sciences, Indiana University, Bloomington
    2. Department of Psychiatry, Indiana University School of Medicine
    3. Larue D. Carter Memorial Hospital, Indianapolis, IN, USA
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  • Anantha Shekhar,

    1. Department of Psychological and Brain Sciences, Indiana University, Bloomington
    2. Department of Psychiatry, Indiana University School of Medicine
    3. Larue D. Carter Memorial Hospital, Indianapolis, IN, USA
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  • William P Hetrick

    1. Department of Psychological and Brain Sciences, Indiana University, Bloomington
    2. Department of Psychiatry, Indiana University School of Medicine
    3. Larue D. Carter Memorial Hospital, Indianapolis, IN, USA
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  • The authors of this paper do not have any commercial associations that might pose a conflict of interest in connection with this manuscript.

  • 1

    Although the pharmacokinetic studies were funded by Bristol-Myers Squibb and Lilly Research Laboratories, the present study was not, and was conducted independently.

  • 2

    Analyses were also performed between the non-psychiatric control group and the BPD patients as a whole with comparable results: Bonferroni-corrected post-hoc comparisons revealed that all significant group differences were attributable to differences between the mixed episode patients and controls.

  • 3

    Although inspection of Fig. 2 suggests an outlier in the healthy control (HC) group for the amplitude conditions, this individual did not meet the criterion (i.e., data values >6 quartiles from the upper or lower ends of the interquartile range) for removal as an extreme outlier. It can be noted, however, that removal of this individual did not affect statistical results.

William P Hetrick, PhD, Department of Psychology, Indiana University, 1101 East Tenth Street, Bloomington, IN 47405, USA. Fax: +1 812 856 4544; e-mail: whetrick@indiana.edu

Abstract

Objectives:  Few studies have examined acoustic startle sensorimotor gating in bipolar disorder (BPD) despite the fact that patients with BPD have exhibited inhibitory dysfunctions on a variety of early information processing tasks. The present study aimed to expand the current literature through the investigation of electromyographic (EMG) measures of acoustic startle prepulse inhibition (PPI) in manic and mixed episode BPD.

Methods:  Fourteen manic and 21 mixed episode BPD patients were compared to 32 healthy controls on acoustic startle measures of PPI using a 120-ms lead interval.

Results:  Prepulse inhibition did not significantly differ across diagnostic groups (manic, mixed, control), and the presence of psychosis in the patient sample was not significantly related to PPI levels. With respect to startle response characteristics, patients in the mixed phase of the disorder showed prolonged prepulsed startle latency and attenuated responses to both probe-alone and prepulsed probes, though no differences in startle habituation were found across diagnostic groups.

Conclusions:  Although PPI deficits were not observed in either BPD sub-group, attenuated probe-alone and prepulsed startle magnitudes and reduced prepulse-induced latency facilitation in the mixed episode group is consistent with evidence that the mixed phase of BPD is associated with a more severe clinical outlook than other stages of the disorder. The absence of attenuated PPI in the patient sample may be due to the low incidence of psychosis in the BPD groups, though further studies are required to systematically assess the effects of symptom factors and clinical phase on sensorimotor gating in BPD.

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