[The association of serum folate levels with schizophrenia symptoms]

To evaluate the association of serum folate levels with schizophrenia and its clinical characteristics in patients from a Russian sample.

Ninety-three patients with schizophrenia and 60 healthy volunteers were examined. Determination of serum folate levels was performed by chemiluminescent immunoassay on microparticles (Architect, Abbott Lab SA). Symptoms of schizophrenia were assessed with the Positive and Negative Syndrome Scale, the Calgary Schizophrenia Depression Scale, the Snight-Hamilton Anhedonia Scale, the Brief Assessment of Cognition in Schizophrenia, the Personal and Social Performance Scale, the Scale for Therapy Side-Effects assessment, Simpson-Angus scales, abnormal involuntary movements scale, Barnes akathisia rating scale. Statistical analysis was performed using the Statistica 6.0. Since the data distribution was different from normal, non-parametric criteria were used.

Patients had significantly lower folate levels than healthy controls (p=0.00053), mainly in women (p=0.0025). At the same time, in all the subgroups (including healthy ones), the vast majority of the participants had folate levels below the median (9.95 ng/ml) and in the lower quartile of the reference values. In patients, folate levels are inversely correlated with the severity of most negative symptoms and directly correlated with all measures of cognitive functions. Patients with folate levels below the reference values differed from other patients by a greater severity of the total score of negative symptoms (p=0.023), Marder's factors of negative symptoms (p=0.046) and disorganized thinking (p=0.033), a greater severity of general side effects of therapy (p=0.021) and all measures of cognitive functions except for verbal memory. Smoking has a significant effect on serum folate levels in all participants (p=0.016). There was also an inverse association of folate levels with the selectivity of antipsychotics (p=0.035), and more severe folate deficiency in inpatients than outpatients (p=0.0063).

The results obtained in the Russian sample on the association of folate deficiency with schizophrenia and a wide range of clinical indicators, including those affecting the prognosis of schizophrenia, indicate the high relevance of further study of this topic and the introduction of approaches to augmentation of antipsychotic therapy for schizophrenia with folates.