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Apathy but Not diminished expression in schizophrenia is associated with discounting of monetary rewards by physical effort


Hartmann, Matthias N; Hager, Oliver M; Reimann, Anna V; Chumbley, Justin R; Kirschner, Matthias; Seifritz, Erich; Tobler, Philippe N; Kaiser, Stefan (2015). Apathy but Not diminished expression in schizophrenia is associated with discounting of monetary rewards by physical effort. Schizophrenia Bulletin, 41(2):503-512.

Abstract

Negative symptoms in schizophrenia have been grouped into the 2 factors of apathy and diminished expression, which might be caused by separable pathophysiological mechanisms. Recently, it has been proposed that apathy could be due to dysfunctional integration of reward and effort during decision making. We asked whether apathy in particular is associated with stronger devaluation ("discounting") of monetary rewards that require physical effort. Thirty-one patients with schizophrenia and 20 healthy control participants performed a computerized effort discounting task in which they could choose to exert physical effort on a handgrip to obtain monetary rewards. This procedure yields an individual measure for the strength of effort discounting. The degree of effort discounting was strongly correlated with apathy, but not with diminished expression. Importantly, the association between apathy and effort discounting was not driven by cognitive ability, antipsychotic medication, or other clinical and demographic variables. This study provides the first evidence for a highly specific association of apathy with effort-based decision making in patients with schizophrenia. Within a translational framework, the present effort discounting task could provide a bridge between apathy as a psychopathological phenomenon and established behavioral tasks to address similar states in animals.

Abstract

Negative symptoms in schizophrenia have been grouped into the 2 factors of apathy and diminished expression, which might be caused by separable pathophysiological mechanisms. Recently, it has been proposed that apathy could be due to dysfunctional integration of reward and effort during decision making. We asked whether apathy in particular is associated with stronger devaluation ("discounting") of monetary rewards that require physical effort. Thirty-one patients with schizophrenia and 20 healthy control participants performed a computerized effort discounting task in which they could choose to exert physical effort on a handgrip to obtain monetary rewards. This procedure yields an individual measure for the strength of effort discounting. The degree of effort discounting was strongly correlated with apathy, but not with diminished expression. Importantly, the association between apathy and effort discounting was not driven by cognitive ability, antipsychotic medication, or other clinical and demographic variables. This study provides the first evidence for a highly specific association of apathy with effort-based decision making in patients with schizophrenia. Within a translational framework, the present effort discounting task could provide a bridge between apathy as a psychopathological phenomenon and established behavioral tasks to address similar states in animals.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:03 Faculty of Economics > Department of Economics
04 Faculty of Medicine > Psychiatric University Hospital Zurich > Clinic for Psychiatry, Psychotherapy, and Psychosomatics
04 Faculty of Medicine > Institute of Biomedical Engineering
Dewey Decimal Classification:610 Medicine & health
330 Economics
Language:English
Date:March 2015
Deposited On:11 Nov 2014 14:25
Last Modified:08 Dec 2017 08:02
Publisher:Oxford University Press
ISSN:0586-7614
Additional Information:This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Schizophrenia Bulletin following peer review. The definitive publisher-authenticated version is available online at:DOI: 10.1093/schbul/sbu102
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1093/schbul/sbu102
PubMed ID:25053653

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