A naturalistic longitudinal study of at-risk mental state with a 2.4 year follow-up at a specialized clinic setting in Japan

Abstract

ObjectiveThe notion of at-risk mental state (ARMS) is valuable for identifying individuals in a putative prodromal state of psychosis and for reducing conversion risk by pharmacological and psychological interventions. However, further systematic study is required because 1) diagnostic reliability in various clinical settings is not yet established; 2) predictive ability is insufficient; 3) optimal interventions in diversified populations are elusive; and 4) little evidence from non-Western regions exists. MethodsA naturalistic longitudinal study was conducted at a specialized clinic for early psychosis at a university hospital in Sendai, Japan. Individuals with ARMS (n=106) were recruited and followed up with case-by-case treatment. ResultsTwo-thirds of the participants were psychiatrist referrals, and 83 were followed up for at-least 1year (mean follow-up=2.4years). Fourteen developed psychosis and the estimated (by Kaplan–Meier) cumulative transition rate was 11.1% at 12, 15.4% at 24, and 17.5% at 30months. At the end-point, about 30% of the 83 followed-up participants including 11 converters received antipsychotic medication. Compared to non-converters, converters showed more severe attenuated psychotic symptoms, including ego-boundary disturbance, formal thought disorder, and emotional disturbance. ConclusionsThe present study replicated previous major Western longitudinal studies, in terms of clinical characteristics, psychosis transition rate, and antipsychotic prescription rate. Our results emphasize the importance of phenomenological assessment of ARMS and intensive care in a clinical setting.