Koji Tsuruga, Norio Sugawara, Yasushi Sato, Manabu Saito, Hanako Furukori, Taku Nakagami, Kazuhiko Nakamura, Ippei Takahashi, Shigeyuki Nakaji, Norio Yasui-Furukori

It has been reported that the onset of schizophrenia and the physical complications after its onset are related to diet. Diet has been considered as a variable factor of the pathogenesis of schizophrenia. However, the results of studies on this relationship have been inconsistent. Nutrients are consumed as a mixture in the diet. It is difficult to study them in isolation because they may have mutually complementary effects. The aim of this study was to assess the association between dietary patterns and schizophrenia in Japan. The subjects comprised 237 outpatients aged 30-60 years (123 males and 114 females) with diagnoses of either schizophrenia or schizoaffective disorder. The patient diagnoses were determined based on medical records. Patients were recruited between June 2011 and August 2011. As a reference group, 404 healthy volunteers aged 30-60 years (158 males and 246 females) were also included. Demographic data (age, sex, and level of education) were collected by face-to-face method interviews and self-administered questionnaires. We assessed eating habits over the last month using a validated brief self-administered diet history questionnaire. We detected dietary patterns through a principal component analysis of calorie-adjusted intake; two principal components were retained. The principal components for each dietary pattern and for each individual were divided into tertiles by principal component scores. We derived two dietary patterns by principal component analysis; namely, the "vegetable" dietary pattern and the "cereal" dietary pattern. In the "cereal" dietary pattern, the high tertile was associated with a significantly increased risk of schizophrenia (P<0.001). The "cereal" dietary pattern is associated with schizophrenia. This article is the first to describe a study examining the association of dietary pattern and schizophrenia.