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Shared and dissociable features of apathy and reward system dysfunction in bipolar I disorder and schizophrenia


Kirschner, Matthias; Cathomas, Flurin; Manoliu, Andrei; Habermeyer, Benedikt; Simon, Joe J; Seifritz, Erich; Tobler, Philippe N; Kaiser, Stefan (2019). Shared and dissociable features of apathy and reward system dysfunction in bipolar I disorder and schizophrenia. bioRxiv n/a, Cold Spring Harbor Laboratory.

Abstract

Background: Bipolar disorder I (BD-I) is defined by episodes of mania, depression, and euthymic states. These episodes are among other symptoms characterized by altered reward processing and negative symptoms (NS), in particular apathy. However, the neural correlates of these deficits are not well understood. Methods: We first assessed the severity of negative symptoms in 25 euthymic BD-I patients compared to 25 healthy controls (HC) and 27 patients with schizophrenia (SZ). Then, we investigated ventral and dorsal striatal activation during reward anticipation in a Monetary Incentive Delayed Task and its association with NS. Results: In BD-I patients NS were clearly present and the severity of apathy was comparable to SZ patients. Apathy scores in the BD-I group but not in the SZ group correlated with sub-syndromal depression scores. At the neural level, we found significant ventral and dorsal striatal activation in BD-I patients and no group differences with HC or SZ patients. In contrast to patients with SZ, apathy did not correlate with striatal activation during reward anticipation. Explorative whole brain analyses revealed reduced extra-striatal activation in BD-I patients compared to HC and an association between reduced activation of the inferior frontal gyrus and apathy. Conclusion: This study found that in BD-I patients apathy is present to an extent comparable to schizophrenia, but is more strongly related to sub-syndromal depressive symptoms. The findings support the view of different pathophysiological mechanisms underlying apathy in the two disorders and suggest that extra-striatal dysfunction may contribute to impaired reward processing and apathy in BD-I.

Abstract

Background: Bipolar disorder I (BD-I) is defined by episodes of mania, depression, and euthymic states. These episodes are among other symptoms characterized by altered reward processing and negative symptoms (NS), in particular apathy. However, the neural correlates of these deficits are not well understood. Methods: We first assessed the severity of negative symptoms in 25 euthymic BD-I patients compared to 25 healthy controls (HC) and 27 patients with schizophrenia (SZ). Then, we investigated ventral and dorsal striatal activation during reward anticipation in a Monetary Incentive Delayed Task and its association with NS. Results: In BD-I patients NS were clearly present and the severity of apathy was comparable to SZ patients. Apathy scores in the BD-I group but not in the SZ group correlated with sub-syndromal depression scores. At the neural level, we found significant ventral and dorsal striatal activation in BD-I patients and no group differences with HC or SZ patients. In contrast to patients with SZ, apathy did not correlate with striatal activation during reward anticipation. Explorative whole brain analyses revealed reduced extra-striatal activation in BD-I patients compared to HC and an association between reduced activation of the inferior frontal gyrus and apathy. Conclusion: This study found that in BD-I patients apathy is present to an extent comparable to schizophrenia, but is more strongly related to sub-syndromal depressive symptoms. The findings support the view of different pathophysiological mechanisms underlying apathy in the two disorders and suggest that extra-striatal dysfunction may contribute to impaired reward processing and apathy in BD-I.

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Additional indexing

Item Type:Working Paper
Communities & Collections:03 Faculty of Economics > Department of Economics
Dewey Decimal Classification:330 Economics
Uncontrolled Keywords:bipolar disorder, euthymic, apathy, diminished expression, fMRI, monetary incentive delay task, negative symptoms, reward anticipation, striatum, transdiagnostic
Language:English
Date:10 February 2019
Deposited On:19 Feb 2019 13:07
Last Modified:30 Jun 2019 07:16
Series Name:bioRxiv
Number of Pages:30
OA Status:Green
Publisher DOI:https://doi.org/10.1101/546036
Official URL:https://www.biorxiv.org/content/10.1101/546036v1

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