DOI: 10.1177/27558428261445159 ISSN: 2755-8428

Circulating levels of homocysteine, folate, and vitamin B12 in adults with and without schizophrenia: A systematic review and meta-analysis

Juan R. Ulloque-Badaracco, Juanita M. Vergara-Peña, Lucero Sangster-Carrasco, Gerardo Contreras-Montoya, Enrique A. Hernandez-Bustamante, Katherin Z. Trujillo-Jurado, Juan C. Cabrera-Guzmán, Cesar Li-Amenero, Percy Herrera-Añazco, Vicente A. Benites-Zapata
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Background:

Schizophrenia is a complex mental disorder with a multifactorial etiology.

Design:

Systematic review and meta-analysis.

Objective:

This study aimed to synthesize the available evidence on circulating levels of homocysteine, folate, and vitamin B12 in adults with and without schizophrenia.

Data sources and methods:

A systematic search was conducted across PubMed, Web of Science, OVID Medline, Embase, and Scopus. The standardized mean difference (SMD) with 95% confidence intervals (CIs) was used for the meta-analysis. A random-effects model was employed using the Sidik-Jonkman method, with 95% CIs adjusted using truncated Knapp-Hartung standard errors.

Results:

A total of 47 studies were included. Compared to healthy controls, adults with schizophrenia had significantly higher homocysteine levels (SMD: 0.96; 95% CI: 0.54–1.37; p  < 0.001; I 2  = 98.47%) and significantly lower folate levels (SMD: −0.53; 95% CI: −0.81 to −0.26; p  < 0.001; I 2  = 93.59%). No significant differences were found in vitamin B12 levels between the schizophrenia and control groups (SMD: −0.38; 95% CI: −0.88 to 0.12; p  = 0.12; I 2  = 97.75%). Similar results were observed when comparing first-episode schizophrenia patients to healthy controls.

Conclusion:

Adults with schizophrenia exhibit elevated homocysteine levels and reduced folate levels, with no significant differences in vitamin B12 levels compared to individuals without schizophrenia.

Trial registration:

PROSPERO ID (CRD42023432883).

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