A research group, led by Director Ryota Hashimoto and Research Fellow Satsuki Ito of the Department of Pathology of Mental Diseases, National Institute of Mental Health, National Center of Neurology and Psychiatry (NCNP), and Professor Chika Sumiyoshi of the Faculty of Human Development and Culture at Fukushima University, revealed that positive symptoms, cognitive decline and daily living skills are involved in the work outcome of schizophrenia patients in a multilayered manner. The study demonstrated that it is important to take a step-by-step intervention approach, from symptom improvement to daily living support, when supporting employment and rehabilitation of these patients. The findings are expected to find applications in clinical practice and were published in Schizophrenia Research: Cognition, issued on June 19.
Schizophrenia is characterized by positive symptoms such as hallucinations and delusions, negative symptoms such as reduced motivation, and cognitive decline, all of which significantly impact social life and employment.
To date, it has been reported that cognitive and social impairments, as well as negative symptoms, are particularly associated with work outcome of these patients.
Meanwhile, patients with severe positive symptoms have difficulty in maintaining stable employment. In clinical practice, it has been empirically believed that improvement of positive symptoms through medication is first priority and should precede other interventions such as those in negative symptoms.
As compared to negative symptoms, structural relationships between positive symptoms and cognitive decline, daily living skills and work outcome had not been sufficiently studied. Moreover, previous studies assessed work outcome with focus on whether the patients were "in work" or "not in work" and did not quantitatively assess their working hours.
In this study, the research group took positive symptoms as the starting point and conducted a comprehensive evaluation of how positive symptoms, cognitive decline and daily living skills influence working hours.
COCORO is a framework of nationwide collaboration involving 54 major medical institutions for investigating the pathology of mental disorders. Within the COCORO framework the group recruited 396 patients with schizophrenia and 1,109 healthy individuals to evaluate the relationships between working hours, cognitive function, social function and positive symptoms. Work outcome was quantified using the Social Activity Assessment to calculate the mean weekly working hours over a 12-week period. Working hours included not only paid employment but also housework and academic studies.
Positive symptoms were assessed using the Positive and Negative Syndrome Scale. Cognitive decline was assessed using the difference between the current IQ, measured by the Wechsler Intelligence Scale, and the estimated premorbid IQ. Social function was assessed using the Social Functioning Scale, with particular focus on items related to daily living skills.
The results revealed that patients had significantly shorter working hours and lower cognitive and social functions compared to healthy controls. Correlation analysis between working hours and other factors revealed that patients showing greater declines in cognitive and social functions and exhibiting severer positive symptoms had shorter working hours.
Using structural equation modeling, they further examined the extent to which daily living skills and cognitive decline influenced working hours. They found two routes through which positive symptoms influenced working hours: one via daily living skills and the other via cognitive decline and then via daily living skills. Furthermore, positive symptoms, cognitive decline and daily living skills all had direct influences on working hours.
It was demonstrated that working hours of patients with schizophrenia are not influenced by a single factor but are determined by a multilayered structure involving multiple correlated factors.
Quantitatively assessing the effect of each factor in individual patients may help with customizing effective interventions. NCNP is currently developing a relatively simple quantitative assessment method that can be used in clinical settings.
Journal Information
Publication: Schizophrenia Research: Cognition
Title: A multilayered model of work outcome in patients with schizophrenia: Examination of the relationships among positive symptoms, cognition, and daily living skills
DOI: 10.1016/j.scog.2026.100444
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