• bipolar disorder
• folic acid
• homocysteine
• vitamin b12

Vitamin B12 (cobalamin), vitamin B9 (folic acid) and homocysteine play a key role in “one-carbon metabolism”, that is a group of biochemical reactions with a special set of enzymes and coenzymes involved in different reactions in the human body, including several brain processes. A growing body of data suggests that a deficiency of B-group vitamins, especially B9 and B12, associated with an increased plasmatic level of homocysteine, are involved in the pathogenesis of central nervous system diseases and in psychiatric disorders given their key roles in development of neuroinflammation processes. As the literature on the topic is quite controversial, evaluating the possible therapeutic implications, the aim of the present study was to assess plasma levels of vitamin B12, folate and homocysteine in a sample of 130 in- and outpatients at the Santa Chiara University Hospital AOUP in Pisa, who meet the DSM-5-TR criteria for a mood episode within bipolar disorders (BDs) of type 1 and 2. Following specific rating scales were used to assess the clinical picture: the Mini International Neuropsychiatric Interview (MINI), the Hamilton Rating Scale for Depression (HAM-D), the Young Mania Rating Scale (YMRS) and the Clinical Global Impression-Severity (CGI-S). The statistical analysis included: the One-way analysis of variance (ANOVA), used to analyze the intergroup differences; the χ2 test (or Fisher’s exact test when appropriate) was applied to evaluate the comparisons for categorical variables. The correlations between different parameters, and between characteristics of the subjects and biological markers were explored by calculating the Pearson’s correlation coefficient or Spearman rank correlation. The results showed that the patients' mean folate, vitamin B12 and homocysteine levels were heterogeneous at different degrees. It was found that subjects with psychotic symptoms, regardless of their diagnosis, had statistically significantly lower vitamin B12 values (Z=-2.43, p=0.015) than subjects without psychotic symptoms. The findings of the present study would suggest the involvement of inflammation processes in BDs and the importance of further investigating the role of vitamin B12, folate and homocysteine in BDs even along the course of the disorder. The potential benefits of vitamins’ supplementation in the treatment of BDs also deserve to be deepened and implemented in controlled trials.