Glutathione levels and activities of glutathione metabolism enzymes in patients with schizophrenia: A systematic review and meta-analysis.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational case-control studies
PubMed 31039654 · doi:10.1177/0269881119845820
What was done
A systematic review and meta-analysis was conducted using Embase, Medline, PsycINFO, and PubMed. Studies comparing three metabolite levels (glutathione, glutathione disulfide, total glutathione) and five enzyme activities (glutathione peroxidase, glutathione reductase, glutamate-cysteine ligase, glutathione synthetase, glutathione S-transferase) between patients with schizophrenia and healthy controls were included. Standardized mean differences were calculated using a random-effects model.
What was found
The authors identified 41, 9, 15, 38, and 7 studies examining glutathione, glutathione disulfide, total glutathione, glutathione peroxidase, and glutathione reductase, respectively. Schizophrenia patients exhibited significantly lower glutathione and total glutathione levels, as well as decreased glutathione peroxidase activity, relative to controls. Glutathione levels were lower in unmedicated patients than in controls, but did not differ between patients with first-episode psychosis and controls. The abstract does not report numerical effect sizes, confidence intervals, or p-values.
Why it matters
The findings support the hypothesis of disrupted antioxidant defense and glutathione redox cycle abnormalities in schizophrenia, highlighting potential biological pathways for therapeutic targeting.
Limits
The abstract reports no exact numbers, effect sizes, variance measures, or participant counts. The underlying studies are observational case-control comparisons subject to confounding from illness duration, tissue type, and lifestyle factors. Very few studies evaluated the entire glutathione system simultaneously.
Cited by
- supports Glutathione levels are low in serious mental illness.