Chika Sumiyoshi1, Haruo Fujino2, Hidenaga Yamamori3, Noriko Kudo4, Hirotsugu Azechi4, Michiko Fujimoto3, Yuka Yasuda3, Kazutaka Ohi5, Tomiki Sumiyoshi6, Ryota Hashimoto7. 1. Faculty of Human Development and Culture, Fukushima University, Fukushima, Fukushima, Japan. Electronic address: sumiyoshi@educ.fukushima-u.ac.jp. 2. Department of Special Needs Education, Oita University, Oita, Oita, Japan. 3. Department of Psychiatry, Osaka University Graduate School of Medicine, Suita, Osaka, Japan. 4. Molecular Research Center for Children's Mental Development, United Graduate School of Child Development, Osaka University, Suita, Osaka, Japan. 5. Department of Neuropsychiatry, Kanazawa Medical University, Uchinada, Ishikawa, Japan. 6. Department of Preventive Intervention for Psychiatric Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. 7. Department of Psychiatry, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; Molecular Research Center for Children's Mental Development, United Graduate School of Child Development, Osaka University, Suita, Osaka, Japan; Department of Pathology of Mental Diseases, National Institute of Mental Health, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan.
Abstract
BACKGROUND: Patients with schizophrenia show various trajectories in intelligence. However, whether the degree of IQ decline is associated with functional outcomes remains unclear. The purposes of the study were 1) to determine whether IQ decline was related with work outcome, and 2) to perform predictions for attaining a certain amount of work measured by work hours. METHODS: One hundred and forty patients with schizophrenia and 156 healthy volunteers enrolled in the study. The patients were classified into the deteriorated group or preserved group based on the degree of IQ decline. In addition to current and premorbid intelligence, functional outcomes and clinical conditions were also evaluated. Those variables were compared among the patient groups and healthy adults to select independent variables for logistic regression analyses. Four separate logistic regression analyses were conducted with work hours dichotomized by four criteria (0, 10, 20, or 30 h per week) as dependent variables. RESULTS: IQ decline remained significant in all regression models except the model with the 30 h per week criterion. Social function and psychiatric symptoms were also prominent factors in most models. Predictions were more accurate in the models with higher criteria. Individual probabilities to exceed each criterion were presented based on the equations derived from the regression models. CONCLUSION: Intellectual deterioration, in addition to impaired social function and psychiatric symptoms, may play a key role in work disturbances in patients with schizophrenia. Probability models presented here have strengths in evaluating the ability to work from statistical, clinical, and theoretical viewpoints.
BACKGROUND:Patients with schizophrenia show various trajectories in intelligence. However, whether the degree of IQ decline is associated with functional outcomes remains unclear. The purposes of the study were 1) to determine whether IQ decline was related with work outcome, and 2) to perform predictions for attaining a certain amount of work measured by work hours. METHODS: One hundred and forty patients with schizophrenia and 156 healthy volunteers enrolled in the study. The patients were classified into the deteriorated group or preserved group based on the degree of IQ decline. In addition to current and premorbid intelligence, functional outcomes and clinical conditions were also evaluated. Those variables were compared among the patient groups and healthy adults to select independent variables for logistic regression analyses. Four separate logistic regression analyses were conducted with work hours dichotomized by four criteria (0, 10, 20, or 30 h per week) as dependent variables. RESULTS: IQ decline remained significant in all regression models except the model with the 30 h per week criterion. Social function and psychiatric symptoms were also prominent factors in most models. Predictions were more accurate in the models with higher criteria. Individual probabilities to exceed each criterion were presented based on the equations derived from the regression models. CONCLUSION: Intellectual deterioration, in addition to impaired social function and psychiatric symptoms, may play a key role in work disturbances in patients with schizophrenia. Probability models presented here have strengths in evaluating the ability to work from statistical, clinical, and theoretical viewpoints.