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Hypoactivation in ventral striatum occurs during reward processing in individuals with psychosis

A meta-analysis indicated individuals with psychosis exhibit ventral striatal hypoactivation during reward anticipation, reward feedback and reward prediction error.

“Positron emission tomography and single-photon emission computed tomography studies have consistently shown that striatal dopamine synthesis capacity is increased in psychosis,” Joaquim Radua, MD, of King’s College London, and colleagues wrote. “Functional [MRI] studies during monetary reward anticipation have also detected altered [ventral striatal] activation in patients experiencing their first episode of psychosis, patients with chronic psychosis, and individuals at clinical or genetic high risk for psychosis. However, these [functional] MRI findings seem inconclusive because some studies found reduced [ventral striatal] activation whereas others reported no abnormalities.”

To assess differences in ventral striatal activation during reward processing among individuals with schizophrenia spectrum disorders and healthy individuals, researchers conducted a meta-analysis of functional MRI studies comparing monetary reward anticipation between individuals with schizophrenia spectrum disorders or clinical or genetic high-risk for psychosis and healthy controls. The analysis included 23 studies on reward anticipation (n = 917), nine on reward feedback (n = 358) and eight on reward prediction error (n = 314).

Researchers found bilateral ventral striatal hypoactivation during reward anticipation compared with healthy controls (P < .001).

Individuals with high scores of negative symptoms during reward anticipation had more severe left ventral striatal abnormality (P < .001).

Individuals with schizophrenia or risk for psychosis also exhibited hypoactivation during reward feedback (P < .001).

Exclusion of studies with nonstatistically significant unreported effects was associated with a strong bias, while estimations using MetaNSUE were unbiased even when statistics were seldom reported, according to researchers.

“The robust finding of [ventral striatal] hypoactivation during reward anticipation may support that psychosis is characterized by impaired learning of stimulus-reinforcement associations,” Radua and colleagues wrote. “However, studies of reward anticipation did not investigate the learning process directly but rather the neural response to reward-indicating cues learned before scanning, and thus our finding may reflect a more general blunting of [ventral striatal] responsivity rather than a specific deficit during reinforcement learning.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.