Identification of Factors to Predict Transition to Schizophrenia in Subjects with Ultra-high risk for Psychosis: A Protocol for a Multicenter, Longitudinal Study of Sleep Parameters and Cytokine Levels
Yuji Yamada1, Kazuo Mishima2, Takashi Ohnishi3, Michio Suzuki4, Takahiro Nemoto5, Masafumi Mizuno6, Toshifumi Kishimoto7,8, Hiroaki Tomita9, Motohiro Ozone10, Shingo Kitamura11, Kenji Hashimoto12, Kazuyuki Nakagome1, Tomiki Sumiyoshi13
1Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
2Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan
3Medical Affairs Division, Janssen Pharmaceutical K.K., Tokyo, Japan
4Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Sciences, Toyama, Japan
5Department of Neuropsychiatry, Toho University Faculty of Medicine, Tokyo, Japan
6Tokyo Metropolitan Matsuzawa Hospital, Tokyo, Japan
7Akitsukounoike Hospital, Nara, Japan
8Department of Psychiatry, Nara Medical University, Nara, Japan
9Department of Psychiatry, Graduate School of Medicine, Tohoku University, Sendai, Japan
10Department of Neuropsychiatry, Kurume University School of Medicine, Fukuoka, Japan
11Department of Sleep-Wake Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo, Japan
12Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
13Department of Preventive Intervention for Psychiatric Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo, Japan
Correspondence to: Tomiki Sumiyoshi
Department of Preventive Intervention for Psychiatric Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi-cho, Kodaira, Tokyo 187-8551, Japan
E-mail: sumiyot@ncnp.go.jp
ORCID: https://orcid.org/0000-0001-9629-1671
Received: September 2, 2024; Revised: November 10, 2024; Accepted: November 11, 2024; Published online: December 3, 2024.
© The Korean College of Neuropsychopharmacology. All rights reserved.

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Abstract
Objective: Schizophrenia is a major psychiatric illness which mostly begins in adolescence and leads to impairments of social functioning. Some patients with schizophrenia have been associated with ultra-high risk state for psychosis (UHR), a condition used to operationally represent the prodromal stage of the illness. In previous studies, the UHR and the progression to overt psychosis has been reported to be accompanied with alterations in the quality of sleep and the immune system, as represented by change of blood levels of cytokines. Currently, biomarkers to predict the development of psychosis in persons at UHR have not yet reached a steady consensus. Therefore, we present a study protocol to explore predictors of transitions to psychosis, in the realm of monitoring of sleep condition and cytokine measurement, in subjects with the UHR.
Methods: This is a multicenter, longitudinal cohort study participated by 7 hospitals in Japan. We will recruit 50 UHR people and 30 healthy volunteers as a control group, and measure positive symptom, depressive symptoms, cognitive function, and social function. Blood cytokines levels and sleep indices, as well as actigraphy data will be monitored. After the baseline assessment, clinical symptoms, sleep indices, and cytokine levels will be measured every 12 weeks for 52 weeks. Actigraphy devices will continue to be worn for 52 weeks, while social function will be assessed over 104 weeks. The results of this study are expected to facilitate the development of novel intervention therapies to reduce the risk of psychosis and improve functional outcomes.
Keywords: Schizophrenia; Ultra-high risk; At-risk mental state; Psychotic disorders; Sleep; Cytokines

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