The treatment response for the negative symptoms of schizophrenia is not ideal, and the efficacy of antidepressant treatment remains a matter of considerable controversy. This systematic review and meta-analysis aimed to assess the efficacy of adjunctive antidepressant treatment for negative symptoms of schizophrenia under strict inclusion criteria.

A systematic literature search (PubMed/Web of Science) was conducted to identify randomized, double-blind, effect-focused trials comparing adjuvant antidepressants with placebo for the treatment of negative symptoms of schizophrenia from database establishment to April 16, 2025. Negative symptoms were examined as the primary outcome. Data were extracted from published research reports, and the overall effect size was calculated using standardized mean differences (SMD).

A total of 15 articles, involving 655 patients, were included in this review. Mirtazapine (N = 2, n = 48, SMD −1.73, CI −2.60, −0.87) and duloxetine (N = 1, n = 64, SMD −1.19, CI −2.17, −0.21) showed significantly better efficacy for negative symptoms compared to placebo. In direct comparisons between antidepressants, mirtazapine showed significant differences compared to reboxetine, escitalopram, and bupropion, but there were no significant differences between other antidepressants or between antidepressants and placebo. No publication bias for the prevalence of this condition was observed.

These findings suggest that adjunctive use of mirtazapine and duloxetine can effectively improve the negative symptoms of schizophrenia in patients who are stably receiving antipsychotic treatment. Therefore, incorporating antidepressants into future treatment plans for negative symptoms of schizophrenia is a promising strategy that warrants further exploration.

Internet gaming disorder (IGD) is a type of behavioural addictions. One of the key features of addiction is the excessive exposure to addictive objectives (e.g. drugs) reduces the sensitivity of the brain reward system to daily rewards (e.g. money). This is thought to be mediated via the signals expressed as dopaminergic reward prediction error (RPE). Emerging evidence highlights blunted RPE signals in drug addictions. However, no study has examined whether IGD also involves alterations in RPE signals that are observed in other types of addictions.

To fill this gap, we used functional magnetic resonance imaging data from 45 IGD and 42 healthy controls (HCs) during a reward-related prediction-error task and utilised a psychophysiological interaction (PPI) analysis to characterise the underlying neural correlates of RPE and related functional connectivity.

Relative to HCs, IGD individuals showed impaired reinforcement learning, blunted RPE signals in multiple regions of the brain reward system, including the right caudate, left orbitofrontal cortex (OFC), and right dorsolateral prefrontal cortex (DLPFC). Moreover, the PPI analysis revealed a pattern of hyperconnectivity between the right caudate, right putamen, bilateral DLPFC, and right dorsal anterior cingulate cortex (dACC) in the IGD group. Finally, linear regression suggested that the connection between the right DLPFC and right dACC could significantly predict the variation of RPE signals in the left OFC.

These results highlight disrupted RPE signalling and hyperconnectivity between regions of the brain reward system in IGD. Reinforcement learning deficits may be crucial underlying characteristics of IGD pathophysiology.