Predictors of Motivational Deficits in Schizophrenia
thesisposted on 21.10.2015, 00:00 by Emily K. Olsen
Reductions in motivational drive are an increasingly studied phenomenon in people with schizophrenia (SZ) as deficits in this area strongly relate to functional outcome. Interestingly, SZ show similar levels of enjoyment in response pleasant experiences as do healthy individuals (HC). Therefore a challenge facing the field is to explain the incongruence between hedonic drives and motivated behavior in schizophrenia. To address this issue, the present study utilized a novel task designed to assess hedonic response and expended effort (i.e., motivation) for rewards akin to those encountered in daily life. Twenty-four individuals with schizophrenia and 27 control participants viewed humorous and non-humorous film scenes and performed an effortful task at varying degrees of difficulty in order view additional scenes from their preferred film. Participants rated their consummatory liking and anticipatory wanting of the stimuli throughout the task. As predicted, SZ and HC reported similar levels of hedonic enjoyment to rewarding stimuli. Group differences in exerted effort were not observed at low to moderate levels of required effort. While ratings of anticipatory wanting to the stimuli were predictive of exerted effort among the HC, this was not true of SZ. Further, SZ chose to expend less effort than HC at higher levels of required effort. Results converge with literature showing that motivational impairments in SZ relate to difficulties modulating behavior to obtain reward, particularly when effort demands increase. Translated to daily life, people with schizophrenia may be biased in judging the positive outcomes associated with difficult or effortful behavior. Results are also considered in light of social-contextual variables and clinical symptoms associated with motivational drives.