background Studies have shown links between homocysteine metabolism and schizophrenia. This may have implications for treatment.
aim To investigate the problem by means of a critical discussion of the literature.
method Publications from 1970 - 2002 were located via PubMed using the search words homocysteine and schizophrenia.
results Impaired homocysteine metabolism is not specific to schizophrenia. However, there are indications that hyperhomocysteinemia occurs more frequently in patients with schizophrenia than in controls. There may well be a link between schizophrenia and genetic variation (combined with folic acid deficiency). There may be a connection between a mutation of a gene coding for an enzyme involved in the metabolism of homocysteine and a positive response to antipsychotics. It is possible that a sub-clinical lack of folic acid and vitamin B12 during pregnancy renders the foetus vulnerable to schizophrenia.
conclusion These findings argue in favour of folic acid supplementation in pregnancy. Because of the frequent occurrence of hyperhomocysteinemia and other cardiovascular risk factors in patients with schizophrenia it may be advisable to assess their homocysteine serum level and to start prescribing folic acid and vitamin B12 if hyperhomocysteinemia is present.