Improvement of Brain Reward Abnormalities by Antipsychotic Monotherapy in Schizophrenia

Abstract

CONTEXT Schizophrenic symptoms are linked to a dysfunction of dopamine neurotransmission and the brain reward system. However, it remains unclear whether antipsychotic treatment, which blocks dopamine transmission, improves, alters, or even worsens the reward-related abnormalities. OBJECTIVE To investigate changes in reward-related brain activations in schizophrenia before and after antipsychotic monotherapy with a dopamine D2/D3 antagonist. DESIGN Longitudinal cohort study. SETTING Psychiatric inpatients and outpatients in the Capital Region of Denmark. PARTICIPANTS Twenty-three antipsychotic-naive patients with first-episode schizophrenia and 24 healthy controls initially matched on age, sex, and parental socioeconomic status were examined with functional magnetic resonance imaging while playing a variant of the monetary incentive delay task. INTERVENTIONS Patients were treated for 6 weeks with the antipsychotic compound amisulpride. Controls were followed up without treatment. MAIN OUTCOME MEASURES Task-related blood oxygen level-dependent activations as measured by functional magnetic resonance imaging before and after antipsychotic treatment. RESULTS At baseline, patients, as compared with controls, demonstrated an attenuation of brain activation during reward anticipation in the ventral striatum, bilaterally. After 6 weeks of treatment, patients showed an increase in the anticipation-related functional magnetic resonance imaging signal and were no longer statistically distinguishable from healthy controls. Among the patients, there was a correlation between the improvement of positive symptoms and normalization of reward-related activation. Those who showed the greatest clinical improvement in positive symptoms also showed the greatest increase in reward-related activation after treatment. CONCLUSIONS To our knowledge, this is the first controlled, longitudinal study of reward disturbances in schizophrenic patients before and after their first antipsychotic treatment. Our results demonstrate that alterations in reward processing are fundamental to the illness and are seen prior to any treatment. Antipsychotic treatment tends to normalize the response of the reward system; this was especially seen in the patients with the most pronounced treatment effect on the positive symptoms. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01154829.

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“…15 The different results could be due to the fact that our study design included only reward conditions, while Nielsen and colleagues employed a salience contrast. 58,59 In addition, our patients were treated with atypical antipsychotics. However, in our subsample of medicated patients the dose of atypical antipsychotics was not associated with ventral striatal activation.…”

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