Lower folate levels in methamphetamine-induced psychosis: A cross-sectional study.

BACKGROUND: Folate deficiency is shown to be associated with schizophrenia. Folate profile in patients with psychosis due to stimulant use has not been investigated. We aim to determine whether there is an association between serum folate level and the presence of psychosis in patients with methamphetamine (METH) use disorder. METHODS: Forty patients diagnosed with METH-use disorder were included in this cross-sectional study. Serum folate levels were measured using enzyme immunoassay technique and compared between psychotic and non-psychotic subgroups (N = 25 and 15, respectively). We designed a logistic regression model to measure the extent of any association and also to adjust for potential confounders. RESULTS: We detected lower serum folate level in the psychotics [3.4 (IQR = 5.3)] compared to non-psychotic METH users [8.9 (IQR = 2.5)], p = 0.01. The model demonstrated that every 1-unit increase in serum folate decreases the odds of presence of psychosis by 27% (R2 = 53.5%, CI 12-64%, p = 0.006). The observed difference was not associated with the duration of METH use, patient's age at first METH use, or concurrent use of other substances. CONCLUSIONS: Our findings suggest that low folate level in psychotic METH users does not correlate with previously established risk factors for meth-induced psychosis such as duration of use, age of onset of using, and poly-drug use. We assume that low folate levels may play a crucial role in the pathophysiology of psychosis.