Caffeine consumption and schizophrenia: a systematic review and meta-analysis of cognitive, symptomatic and functional outcomes.

BACKGROUND

Caffeine's impact on schizophrenia, a disorder marked by cognitive and functional deficits, is unclear. We evaluated the impact of caffeine on cognition, symptoms, and functioning in patients with schizophrenia.

METHOD: A PRISMA-guided systematic review searched six databases up to 30 December 2024. English-language studies of adults with schizophrenia comparing different caffeine intake levels and reporting outcomes on cognition, symptoms, or functioning were included. Data were synthesized via a random-effects model with Hedges' g for effect size and I2 statistics for heterogeneity. Prospectively registered on PROSPERO (CRD42025628484).

RESULTS

Of 252 articles screened, eleven (n = 1,406) met inclusion criteria. Individual study findings were mixed: some studies reported benefits for negative symptoms, others noted increased positive symptoms. Meta-analyses revealed no significant effects on overall symptom severity (measured with the Brief Psychiatric Rating Scale (BPRS) and the Nurses' Observation Scale for Inpatient Evaluation (NOSIE)).

CONCLUSION

The influence of caffeine on schizophrenia is multifaceted, offering potential benefits for negative symptoms and specific cognitive domains while posing risks for positive symptom exacerbation. Given the heterogeneity in functional outcomes and the potential for interactions with antipsychotic medications, clinical management should be individualized. Future research must prioritize high-quality, longitudinal trials to resolve current inconsistencies and guide standardized clinical recommendations.