Estimated cognitive decline in patients with schizophrenia: A multicenter study.
OBJECTIVE
Studies have reported that cognitive decline occurs after the onset of schizophrenia despite heterogeneity in cognitive function among patients. The aim of this study was to investigate the degree of estimated cognitive decline in patients with schizophrenia by comparing estimated premorbid intellectual functioning and current intellectual functioning.


METHODS
A total of 446 patients with schizophrenia (228 male, 218 female), consisting of three sample sets obtained from 11 psychiatric facilities, and 686 healthy controls participated in this study. The Wechsler Adult Intelligence Scale-III (WAIS-III) was used to measure the participants' current full-scale IQ (FSIQ). The premorbid IQ was estimated using the Japanese Adult Reading Test-25. Estimated cognitive decline (difference score) was defined as the difference between the estimated premorbid IQ and the current FSIQ.


RESULTS
Patients with schizophrenia showed greater estimated cognitive decline, a lower FSIQ, and a lower premorbid IQ compared with the healthy controls. The mean difference score, FSIQ, and estimated premorbid IQ were -16.3, 84.2, and 100.5, respectively, in patients with schizophrenia. Furthermore, 39.7% of the patients had a difference score of 20 points or greater decline. A discriminant analysis showed that the difference score accurately predicted 81.6% of the patients and healthy controls.


CONCLUSIONS
These results show the distribution of difference score in patients with schizophrenia. These findings may contribute to assessing the severity of estimated cognitive decline and identifying patients with schizophrenia who suffer from cognitive decline.
Graduate School of Human Sciences, Osaka University, Osaka, Japan.|Graduate School of Education, Oita University, Oita, Japan.
Haruo
H
Fujino
Faculty of Human Development and Culture, Fukushima University, Fukushima, Japan.
Chika
C
Sumiyoshi
Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan.
Yuka
Y
Yasuda
Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan.
Hidenaga
H
Yamamori
Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan.
Michiko
M
Fujimoto
Division of Cerebral Integration, National Institute for Physiological Sciences, Aichi, Japan.
Masaki
M
Fukunaga
Graduate School of Medicine, Department of Integrative Brain Science, Kyoto University, Kyoto, Japan.
Kenichiro
K
Miura
Department of Psychiatry, Faculty of Medicine, Juntendo University, Tokyo, Japan.
Yuto
Y
Takebayashi
Graduate School of Medicine, Department of Neuropsychiatry, The University of Tokyo, Tokyo, Japan.
Naohiro
N
Okada
Graduate School of Medical Sciences, Department of Neuropsychiatry, Kyushu University, Fukuoka, Japan.
Shuichi
S
Isomura
Green Mobility Research Institute, Institutes of Innovation for Future Society, Nagoya University, Aichi, Japan.|Department of Psychiatry, Nagoya University Graduate School of Medicine, Aichi, Japan.
Naoko
N
Kawano
Graduate School of Medicine, Department of Psychiatry, Hokkaido University, Sapporo, Japan.
Atsuhito
A
Toyomaki
Graduate School of Medical Sciences, Department of Neuropsychiatry, Kyushu University, Fukuoka, Japan.|Division of Clinical Research, National Hospital Organization, Hizen Psychiatric Center, Saga, Japan.
Hironori
H
Kuga
Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Masanori
M
Isobe
Department of Psychiatry, Fujita Health University School of Medicine, Aichi, Japan.
Kazuto
K
Oya
Department of Neuropsychiatry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Yuko
Y
Okahisa
Department of Neuropsychiatry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Manabu
M
Takaki
Graduate School of Medicine, Department of Psychiatry, Hokkaido University, Sapporo, Japan.
Naoki
N
Hashimoto
Department of Neuropsychiatry, Kansai Medical University, Osaka, Japan.
Masaki
M
Kato
Graduate School of Medical Sciences, Department of Neuropsychiatry, Kyushu University, Fukuoka, Japan.
Toshiaki
T
Onitsuka
Graduate School of Medical Sciences, Department of Neuropsychiatry, Kyushu University, Fukuoka, Japan.|Division of Clinical Research, National Hospital Organization, Hizen Psychiatric Center, Saga, Japan.
Takefumi
T
Ueno
Department of Psychiatry, Faculty of Medicine, Juntendo University, Tokyo, Japan.
Tohru
T
Ohnuma
Graduate School of Medicine, Department of Neuropsychiatry, The University of Tokyo, Tokyo, Japan.
Kiyoto
K
Kasai
Department of Psychiatry, Nagoya University Graduate School of Medicine, Aichi, Japan.
Norio
N
Ozaki
Department of Clinical Epidemiology, Translational Medical Center, National Center of Neurology and Psychiatry, Tokyo, Japan.
Tomiki
T
Sumiyoshi
Graduate School of Human Sciences, Osaka University, Osaka, Japan.
Osamu
O
Imura
Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka, Japan.|Molecular Research Center for Children's Mental Development, United Graduate School of Child Development, Osaka University, Osaka, Japan.
Ryota
R
Hashimoto
D000328:Adult; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000150:complications* / Q000523:psychology*; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D012559:Schizophrenia / Q000150:complications*; D012565:Schizophrenic Psychology; D055815:Young Adult
cognition; cognitive decline; intelligence; multicenter study; schizophrenia