Abstract
Background
Prior studies indicate that chronic schizophrenia (SZ) is associated with a specific profile of reinforcement learning abnormalities. These impairments are characterized by: 1) reductions in learning rate, and 2) impaired Go learning and intact NoGo learning. Furthermore, each of these deficits are associated with greater severity of negative symptoms, consistent with theoretical perspectives positing that avolition and anhedonia are associated with deficits in generating, updating, and maintaining mental representations of reward value hat are needed to guide decision-making. However, it is unclear whether these deficits extend to earlier phases of psychotic illness and when individuals are unmedicated.
Methods
Two studies were conducted to examine reinforcement learning deficits in earlier phases of psychosis. In study 1, participants included 35 participants with first episode psychosis (FEP) and 25 healthy controls (HC). Study 2 included 17 antipsychotic naïve individuals who met criteria for attenuated psychosis syndrome (APS) (i.e., those with a prodromal syndrome) and 18 matched healthy controls (HC). In both studies, participants completed the Temporal Utility Integration Task, a measure of probabilistic reinforcement learning that contained Go and NoGo learning blocks. Participants in the clinical groups also completed neuropsychological testing and standard clinical interviews designed to determine symptom severity and diagnosis.
Results
FEP displayed impaired Go learning and intact NoGo learning. In contrast, APS did not display impairments in Go or NoGo learning at the group level. Negative symptoms were not significantly associated with reinforcement learning in APS participants. However, greater impairments in Go learning were associated with increased cross-sectional risk for conversion on the NAPLS risk calculator score in the APS group.
Discussion
Findings provide new evidence for areas of spared and impaired reinforcement learning in early phases of psychosis. Similar to chronic SZ, FEP was associated with impaired Go learning, and intact NoGo learning. Reinforcement learning is more spared in those at clinical high-risk, except those at greatest risk for conversion, where Go learning deficits are more pronounced. These findings suggest that reinforcement learning deficits may emerge early among those who are at clinical high risk for developing psychosis and that they are already pronounced by illness onset in the first episode. Importantly, these reinforcement learning deficits do not appear to be a byproduct of illness chronicity or antipsychotic medication use, but rather a consequence of the illness itself.
Prediction of disability in schizophrenia: Symptoms, cognition, and self-assessment