Schizophrenia, Syndrome X, and Omega-3 Fatty Acids
To the Editor: In an interesting study, Martina C.M. Ryan, M.B., M.R.C.Psych., et al. (1) found an increased prevalence of impaired glucose tolerance and insulin resistance in patients with drug-naive, first-episode schizophrenia in relation to healthy comparison subjects. This finding is in line with the results of a recent review showing that features of the metabolic syndrome X are more common in subjects with schizophrenia than in the general population (2). Dr. Ryan and colleagues discussed the influence of diet (1), but we believe that they omitted the possible role of polyunsaturated fatty acids of the omega-3 and omega-6 series, in particular, eicosapentaenoic acid and arachidonic acid. Substantial evidence suggests that impaired polyunsaturated fatty acid metabolism is related to both schizophrenia and the metabolic syndrome X. In recent reviews, low consumption of omega-3 polyunsaturated fatty acid was concluded to be associated with hypertriglyceridemia, cardiovascular disease, and probably also to insulin resistance and type 2 diabetes (3–5). Of interest, lowered omega-3 polyunsaturated fatty acid levels have also been reported in the erythrocytes of drug-naive psychotic patients (6) and in medicated young schizophrenic patients in comparison with normal comparison subjects (7). Furthermore, placebo-controlled trials have found eicosapentaenoic acid to be effective in schizophrenia, depression, and borderline personality disorder (8–10).
We believe that randomized, controlled trials are warranted to test whether supplementation with long-chain omega-3 polyunsaturated fatty acid, such as eicosapentaenoic acid, can improve the symptoms of schizophrenia and prevent the development of features of the metabolic syndrome X in subjects with schizophrenia.
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