Glucose-6-phosphate dehydrogenase deficiency and psychotic disorders: A systematic review

Glucose-6-Phosphate Dehydrogenase Deficiency (G6PD) is the most common enzymopathy globally. Early studies suggested an association with severe psychotic illness; however, changes to laboratory testing and diagnostic classification renders the association unclear. This study aims to explore the interaction between G6PD deficiency and psychotic symptoms, in particular to identify specific patterns of presentation or impact on outcomes.

Pubmed, Embase, and PsycInfo databases were searched from inception to May 2023. Descriptive statistics and narrative review of were used to synthesise data on demographics, mental and physical health diagnoses, investigations, treatment, and outcomes.

No clear link was found in published data (eight case reports, case series of n = 29) with a high rate (63%) of haemolytic crisis at the time of psychiatric presentation suggested delirium as an alternative diagnosis. Four case control studies found no significant difference in the prevalence of G6PD deficiency. However, catatonic presentation was reported in 40% of the case series and a higher prevalence of G6PD deficiency in catatonic schizophrenia was noted in case control studies.

Based on the information available there was no clear association between G6PD deficiency and psychotic illness or treatment resistance, although paucity of studies and risk of bias limit strong conclusions.