Clinical and social determinants of a longer duration of untreated psychosis of schizophrenia in a Japanese population


Professor Masafumi Mizuno, Department of Neuropsychiatry, Toho University School of Medicine, 6-11-1, Omori-Nishi, Ota-ku, Tokyo 143-8541, Japan. Email:


Aim: To measure the duration of untreated psychosis (DUP) among patients with schizophrenia in a Japanese population and to investigate clinical and social determinants of the DUP.

Methods: A multicentre, retrospective study at seven medical centres in three cities (Tokyo, Toyama and Kochi) was performed. In total, 150 consecutive patients (78 men) with neuroleptic-naïve first-episode schizophrenia were investigated; their DUP and demographic, clinical and social variables were obtained from their medical charts and analysed.

Results: The intraclass correlation coefficient for the DUP was quite good (ICC = 0.849). The mean DUP of all the subjects attending the seven psychiatric services was 20.3 months, and the median DUP was 6.0 months. Fourteen patients (9.3%) had a DUP of more than 60 months, and 47 patients, or about one-third, had a DUP of more than 24 months. No significant differences in the mean DUPs were observed among the three cities. Patients who were employed or who were students had a significantly shorter DUP (14.3 months). The median DUP for those with an insidious onset of psychosis (n = 85) was 18.0 months, compared with a median of 2.0 months for those with a sudden and acute onset (n = 61). However, no other clinical or social variables examined in this study were associated with differences in the DUP.

Conclusions: The DUP of patients with schizophrenia is relatively long in Japan. The provision and modification of psychiatric services for easy access and a system for the early recognition and detection of mental illness are needed.