Psychiatry and Clinical Neurosciences 2014; 68: 534–541

doi:10.1111/pcn.12165

Regular Article

Performance on the Wechsler Adult Intelligence Scale-III in Japanese patients with schizophrenia Haruo Fujino, MS,1 Chika Sumiyoshi, PhD,5 Tomiki Sumiyoshi, MD, PhD,6 Yuka Yasuda, MD, PhD,3 Hidenaga Yamamori, MD, PhD,3,4 Kazutaka Ohi, MD, PhD,3,7 Michiko Fujimoto, MD, PhD,3 Satomi Umeda-Yano, PhD,4 Arisa Higuchi, MS,3 Yumiko Hibi, BS,1 Yukako Matsuura, MS,1 Ryota Hashimoto, MD, PhD,2,3* Masatoshi Takeda, MD, PhD2,3 and Osamu Imura, PhD1 1 Graduate School of Human Sciences, 2Molecular Research Center for Children’s Mental Development, United Graduate School of Child Development, Osaka University, 3Department of Psychiatry, 4Department of Molecular Neuropsychiatry, Osaka University Graduate School of Medicine, Osaka, 5Faculty of Human Development and Culture, Fukushima University, Fukushima, 6Department of Neuropsychiatry, University of Toyama Graduate School of Medicine and Pharmaceutical Sciences, Toyama and 7National Hospital Organization, Yamato Mental-Medical Center, Nara, Japan

Aim: Patients with schizophrenia have been reported to perform worse than non-schizophrenic populations on neuropsychological tests, which may be affected by cultural factors. The aim of this study was to examine the performance of a sizable number of patients with schizophrenia on the Japanese version of the Wechsler Adult Intelligence Scale-III (WAIS-III) compared with healthy controls. Methods: Performance on the WAIS-III was evaluated in 157 Japanese patients with schizophrenia and in 264 healthy control subjects. Results: All IQ scores and four indices from the WAISIII were impaired for patients with schizophrenia compared with healthy controls. Processing Speed was markedly disturbed, approximately 2 SD below that of the healthy control group. Among the 13

CHIZOPHRENIA IS CHARACTERIZED by positive (e.g., delusions and hallucinations) and negative (e.g., blunted affect and withdrawal) symptoms as well as cognitive deficits.1 Specifically, various

S

*Correspondence: Ryota Hashimoto, MD, PhD, Molecular Research Center for Children’s Mental Development, United Graduate School of Child Development, Osaka University, D3, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan. Email: [email protected] Received 13 March 2013; revised 7 January 2014; accepted 15 January 2014.

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subtests, Comprehension (z = −1.70, d = 1.55), Digit Symbol Coding (z = −1.84, d = 1.88), and Symbol Search (z = −1.85, d = 1.77) were profoundly impaired relative to the healthy controls.

Conclusion: These results indicate that the pattern and degree of impairment, as evaluated by the WAISIII, in Japanese patients are similar to those previously reported in English-speaking patients and that the deficits of some neuropsychological domains relevant to functional outcomes are universally characteristic of schizophrenia. Key words: cognitive impairment, cross-national difference, functional outcome, schizophrenia, Wechsler Adult Intelligence Scale-III.

domains of cognitive function, such as several types of memory, attention, executive function, fluency, and information processing, are impaired in patients with schizophrenia.2–8 Cognitive disturbances are regarded as a core feature of schizophrenia and have been reported to profoundly alter everyday social functioning.9 Most patients with schizophrenia fail to reach their expected level of cognitive functioning estimated from educational level and premorbid intelligence.10 Cognitive impairment appears to be independent of other aspects of the symptomatology

© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology

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of schizophrenia, for example, positive symptoms.11 Although other psychiatric disorders, such as bipolar disorder, also present with cognitive degradation to some degree, patients with schizophrenia exhibit more global and more severe impairment.12–14 Cognitive impairments in schizophrenia are also known to affect everyday functioning and social abilities.15 For these reasons, efforts have been made to enhance cognitive functioning, such as by cognitive rehabilitation, to encourage the patients’ social adjustment.16–18 The Wechsler Adult Intelligence Scale-III (WAISIII)19 has been developed to assess intellectual ability and is frequently used in studies of cognitive abilities in patients with schizophrenia.20–22 Several modifications have been incorporated in the update from the WAIS-Revised (previous version of the WAIS-III) into the WAIS-III. In addition to FullScale IQ (FSIQ), Verbal IQ, and Performance IQ, four new indices have been included: Verbal Comprehension (VC), Perceptual Organization (PO), Working Memory (WM), and Processing Speed (PS). VC is a measure of the ability to understand and provide oral explanations corresponding to certain tasks and to identify abstract concepts. PO measures non-verbal thinking, such as the manipulation of designs and pictures, fluid reasoning, and spatial processing. WM measures the ability to retain information temporarily to perform a designated task. PS measures the ability to perform given tasks quickly and efficiently based on the presented information. Upon adopting these four indices, new subtests have been included in the WAIS-III. Brief descriptions of these tasks and other tasks are provided in Table S1. The reliability of the Japanese version of the WAIS-III was confirmed through a standardization study. The reliability coefficients of the Japanese version of the WAIS-III were calculated using the split-half method and test–retest reliabilities. The mean reliability coefficients across all age groups were 0.81–0.92 for all subtests and 0.91–0.97 for indices and IQs, which showed good reliabilities.23 Despite the accumulation of studies, performance on the WAIS-III has only been grossly reported, and no study has clarified the comprehensive profile of the WAIS-III in populations of patients with schizophrenia. The aim of this study was to examine the performance on the Japanese version of the WAISIII in patients with schizophrenia compared with healthy controls.

Japanese WAIS-III in schizophrenia 535

METHODS Subjects A total of 157 patients with schizophrenia (97 male, 60 female) and 264 healthy control subjects (153 male, 111 female) were included in this study. The patients consisted of inpatients and outpatients treated at the Department of Psychiatry, Osaka University Hospital. A consensus diagnosis, according to the DSM-IV1 criteria, was made by experienced senior psychiatrists using the Structured Clinical Interview for DSM-IV (SCID) for schizophrenia. Psychotic symptoms (positive symptoms, negative symptoms, and general psychopathology) were evaluated using the Positive and Negative Syndrome Scale (PANSS).24 Healthy control subjects were recruited from the community through local advertisements at Osaka University. The healthy control subjects were evaluated psychiatrically, medically, and neurologically, and the DSM-IV-Non-Patient version of the SCID was used to exclude individuals who had current or past contact with psychiatric services or had previously received psychiatric medications. Subjects were excluded from this study if they had neurological or medical conditions that could affect the central nervous system, such as atypical headache, head trauma with loss of consciousness, chronic lung disease, kidney disease, chronic hepatic disease, thyroid disease, cancer in an active stage, cerebrovascular disease, epilepsy, seizures, substancerelated disorders, and mental retardation. All participants provided written informed consent after the study procedures were fully explained. All procedures were conducted according to the Declaration of Helsinki and approved by the Ethical Committee of Osaka University.

Measures The Japanese version of the WAIS-III23 was used. It comprises three IQ categorical scores: Full Scale IQ (FSIQ), Verbal IQ, and Performance IQ. Verbal IQ consists of seven subtests: Vocabulary, Similarities, Arithmetic, Digit Span, Information, Comprehension, and Letter–Number Sequencing. Performance IQ consists of six subtests: Picture Completion, Digit Symbol Coding, Block Design, Matrix Reasoning, Picture Arrangement, and Symbol Search. The subtests of the WAIS-III are grouped into four index scores as

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follows: VC (Vocabulary, Similarities, and Information), PO (Picture Completion, Block Design, and Matrix Reasoning), WM (Arithmetic, Digit Span, and Letter–Number Sequencing), and PS (Digit Symbol Coding and Symbol Search) (Table S1). The raw scores of these subtests were converted to scaled scores. Premorbid IQ was estimated using the Japanese Adult Reading Test (JART).25,26

trols’ scores and the patients’ scores was divided by the pooled SD (weighted by n of each group). Pearson’s correlations were calculated for the patients to examine the correlations between clinical variables and the performance on the WAIS-III.

Statistical analysis Statistical analyses were performed using SPSS 17.0 (SPSS Japan, Tokyo, Japan). Group comparisons of demographic variables were performed using t-tests or χ2-tests, as appropriate. The effects of a psychiatric diagnosis on IQ scores and the WAIS-III indices were analyzed using t-tests. To control for confounding factors, analyses of covariance (ANCOVA) were performed with sex and JART scores as covariates (the significance level was set at two-tailed P < 0.05). A strong correlation is known to exist between JART and years of education; thus, only the former, the index of premorbid intelligence, was included as a covariate. The premorbid and WAIS-III IQ scores and the scores of the four indices and subtests of the WAIS-III were transformed to standardized z-scores on the basis of the means and SD of the healthy control group. In addition, effect size (Cohen’s d) was calculated; the mean difference between the healthy con-

RESULTS Table 1 summarizes the demographic and clinical information of the subjects. Patients and healthy controls did not differ significantly in age, sex, and education years (Ps > 0.05). Table 2 presents premorbid IQ, FSIQ, Verbal IQ, Performance IQ, the four indices, and the scaled scores of the WAIS-III subtests. All the IQ scales and scores of the four indices were significantly lower for the patients with schizophrenia than for the healthy controls (all Ps < 0.001). In contrast to a relatively small decline in premorbid IQ, the patients’ FSIQ, Verbal IQ, and Performance IQ fell between 1.34 and 1.90 SD below normal values (Fig. 1, upper). Performance IQ was 8.4 points below Verbal IQ in the patient group. PS was markedly disturbed, being approximately 2 SD below the healthy control group (z = −2.16, d = 2.06). In contrast, the three other index scores demonstrated a decline of approximately 1 SD (Fig. 1, lower). Performance on the subtests revealed that scores fell significantly below normal (Ps < 0.001). Among the 13 subtests, the deficits of Information (z = −0.62, d = 0.61) and Digit Span (z = −0.49, d = 0.50) were

Table 1. Comparisons of healthy controls and schizophrenia patients on demographic variables Healthy controls (n = 264) Mean Age Sex (Male/Female) Education (years) Age at onset Duration of untreated psychosis (years) Duration of illness (years) CPZeq (mg/day) PANSS positive PANSS negative PANSS general psychopathology

37.5

SD

12.9 153/111 14.1 2.0 – – – – – – – – – – – – – –

Schizophrenia patients (n = 157) Mean

SD

35.9

12.2 97/60

13.9 24.1 2.0 11.8 589.7 19.6 20.1 42.7

2.5 9.4 4.1 9.7 537.4 5.6 5.9 10.3

Statistics

P-value

t342.9 = 1.231 χ2(1) = 0.598 t267.9 = 0.895 – – – – – – –

0.219 0.439 0.372 – – – – – – –

CPZeq, chlorpromazine equivalent of total antipsychotics; PANSS, Positive and Negative Syndrome Scale.

© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology

Psychiatry and Clinical Neurosciences 2014; 68: 534–541

relatively mild, whereas Comprehension (z = −1.70, d = 1.55), Digit Symbol Coding (z = −1.84, d = 1.88), and Symbol Search (z = −1.85, d = 1.77) were markedly impaired relative to the healthy controls (Fig. 2). Correlations between clinical variables and WAISIII indices are shown in Table 3. Age at onset, duration of untreated psychosis, and duration of illness were not correlated with the indices. Correlations between antipsychotic medications and indices were mild to moderate. Positive symptoms were partly correlated with the indices. Correlations between negative symptoms and the indices were moderately correlated. General psychopathology was mildly correlated with the indices. Correlations between clinical variables and the WAIS-III subtests are presented in Table S2 (Supporting Information), representing similar results of the indices.

Japanese WAIS-III in schizophrenia 537

Vocabulary Similarities Information Comprehension Arithmetic Digit Span Letter−Number Sequencing

Picture Arrangement Picture Completion Block Design Matrix Reasoning

Premorbid IQ

Digit Symbol Coding Full Scale IQ

Symbol Search −2.0

Verbal IQ

−1.5

−1.0

−0.5

0.0

z-score Performance IQ

Figure 2. Wechsler Adult Intelligence Scale-III subtests scores. ) Controls, ( ) Patients. The subtest scores were trans( formed to standardized z-scores based on the means and SD of the healthy controls.

Verbal Comprehension

DISCUSSION

Perceptual Organization

This study evaluated the complete profile of the performance of a sizable number of subjects with schizophrenia on the Japanese version of WAIS-III. Performances on the subtests associated with functional outcome and sensitivity to language systems were closely examined.

Working Memory

Processing Speed −2.5

−2.0

−1.5 −1.0 z-score

−0.5

0.0

Figure 1. Scores of premorbid IQ and the Wechsler Adult

Profile of the Japanese version of the WAIS-III

) Controls, ( ) Intelligence Scale-III IQ and four indices. ( Patients. Each score was transformed to standardized z-scores based on the means and SD of the healthy controls. Therefore, the means of the healthy controls are represented by the zero line (SD = 1).

Generally, patients with schizophrenia performed significantly worse on the Japanese WAIS-III, as was reported by previous studies with the English version of the WAIS-III,20,27 even though the patients

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Table 2. Comparison of healthy controls and schizophrenia patients on premorbid IQ, WAIS-III IQ, indices, and subtests Healthy controls (n = 264)

Schizophrenia patients (n = 157)

t-test

ANCOVA

Mean

SD

Mean

SD

t

d.f.

P-value

z

d

Premorbid IQ Full Scale IQ Verbal IQ Performance IQ

106.7 108.0 108.4 105.8

8.0 12.4 13.4 12.4

101.7 85.5 90.5 82.1

10.2 16.6 16.1 16.3

5.23 14.77 11.77 15.67

269.1 259.8 282.1 263.5

NA NA 3.46 × 10−7 2.90 × 10−36 246.5 5.61 × 10−44 2.84 × 10−26 136.3 1.92 × 10−27 1.54 × 10−39 238.8 6.45 × 10−43

−0.62 −1.82 −1.34 −1.90

0.56 1.60 1.24 1.69

Indices Verbal Comprehension Perceptual Organization Working Memory Processing Speed

106.1 105.3 105.7 106.8

13.4 13.2 15.6 13.1

93.2 86.3 88.2 78.4

15.7 17.9 16.5 14.8

8.57 11.56 10.75 19.80

287.3 256.7 314.5 297.1

6.47 × 10−16 49.6 7.94 × 10−12 3.77 × 10−25 121.4 6.02 × 10−25 3.74 × 10−23 90.1 1.77 × 10−19 3.18 × 10−56 356.4 6.61 × 10−58

−0.96 −1.44 −1.12 −2.16

0.90 1.26 1.10 2.06

11.4 11.0 10.8 12.2 11.6 10.8 10.7 10.5 10.4 11.0 11.4 11.3 11.3

3.0 2.4 2.9 2.8 3.0 3.2 3.2 3.4 2.6 3.1 2.8 2.8 2.8

8.8 8.5 9.0 7.5 8.0 9.3 7.5 7.2 7.6 8.2 7.8 6.1 6.2

3.2 3.1 3.0 3.4 3.2 3.0 3.3 3.7 3.4 3.7 3.5 2.7 3.1

8.13 8.75 5.97 14.56 11.60 5.00 9.71 9.22 8.82 8.18 10.84 18.95 17.10

310.5 272.0 314.0 275.8 315.0 342.2 319.1 304.9 261.5 281.2 271.4 343.2 299.4

1.06 × 10−14 2.26 × 10−16 6.58 × 10−9 5.07 × 10−36 3.76 × 10−26 9.10 × 10−7 1.08 × 10−19 5.01 × 10−18 1.70 × 10−16 9.89 × 10−15 5.66 × 10−23 2.49 × 10−55 3.33 × 10−46

3.36 × 10−9 3.46 × 10−12 7.60 × 10−4 3.75 × 10−36 1.18 × 10−23 5.29 × 10−4 2.03 × 10−15 2.91 × 10−14 8.80 × 10−15 1.48 × 10−12 1.69 × 10−21 2.86 × 10−50 4.37 × 10−46

−0.86 −1.03 −0.62 −1.70 −1.21 −0.49 −1.00 −0.98 −1.08 −0.94 −1.28 −1.84 −1.85

0.83 0.94 0.61 1.55 1.19 0.50 0.99 0.95 0.95 0.86 1.16 1.88 1.77

Subtests Vocabulary Similarities Information Comprehension Arithmetic Digit Span Letter–Number Sequencing Picture Arrangement Picture Completion Block Design Matrix Reasoning Digit Symbol Coding Symbol Search

F1, 419

36.5 51.4 11.5 191.8 113.8 12.2 68.1 62.1 64.8 53.3 101.4 294.1 262.1

P-value

Scores of subtests were scaled scores. ANCOVA (covariate = sex, premorbid IQ [Japanese Adult Reading Test]). WAIS-III, Wechsler Adult Intelligence Scale-III.

Table 3. Correlations between clinical variables and WAIS-III indices in patients with schizophrenia

Age at onset Duration of untreated psychosis Duration of illness CPZeq (mg/day) PANSS positive PANSS negative PANSS general psychopathology

FSIQ

VIQ

PIQ

VC

PO

WM

PS

0.079 0.018 0.058 −0.311*** −0.184* −0.434*** −0.290***

0.084 −0.020 0.044 −0.267*** −0.151 −0.428*** −0.268***

0.054 0.054 0.059 −0.325*** −0.199* −0.379*** −0.271***

0.045 −0.070 0.034 −0.218** −0.094 −0.381*** −0.207**

0.016 0.030 0.027 −0.320*** −0.204* −0.327*** −0.249**

0.010 −0.034 0.023 −0.352*** −0.152 −0.352*** −0.239**

0.025 −0.015 0.123 −0.251** −0.084 −0.312*** −0.190*

*P < 0.05, ** P < 0.01, *** P < 0.001 (2 tailed). CPZeq, chlorpromazine equivalent of total anti psychotics; FSIQ, Full-Scale IQ; PANSS, Positive and Negative Syndrome Scale; PIQ, Performance IQ; PO, Perceptual Organization; PS, Processing Speed; VC, Verbal Comprehension; VIQ, Verbal IQ; WAIS-III, Wechsler Adult Intelligence Scale-III; WM, Working Memory.

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were demographically equivalent to the normal controls. Impairment of the patients’ premorbid IQ was relatively mild (z = −0.62, d = 0.56), whereas the performance on the FSIQ was severely disturbed (z = −1.82, d = 1.60), indicating a large decrement from the expected level of cognitive functioning.10 Consistent with previous studies,22,28,29 Performance IQ tended to be below Verbal IQ in patients with schizophrenia. VC was most preserved (z = −0.96, d = 0.90), followed by WM (z = −1.12, d = 1.10) and PO (z = −1.44, d = 1.26). PS was markedly impaired in schizophrenic patients (z = −2.16, d = 2.06). Previous studies have reported that VC and PS were associated with community functioning and vocational functioning.27,30 Specifically, PS is one of the most negatively affected cognitive abilities in schizophrenia.6,31,32 Generally, scores of the 13 subtests were slightly lower than those of a previous study;33 however, the profile pattern in the patients studied here was similar to those reported in the literature. Among the 13 subtests, Comprehension (z = −1.70, d = 1.55), Digit Symbol Coding (z = 1.84, d = 1.88), and Symbol Search (z = −1.85, d = 1.77) were severely impaired, as was shown in studies using the WAIS-R.6 Comprehension and Digit Symbol Coding were closely associated with functional outcome in patients with schizophrenia and first-episode psychosis.27,30,34 The Information (z = −0.62, d = 0.61) and Digit Span (z = −0.49, d = 0.50) subtests were relatively preserved, consistent with a previous study.21,35 The former subtest is considered to reflect crystallized intelligence, which may not be largely affected by the illness. Negative symptoms and general psychopathology were moderately correlated with all indices of WAISIII, as reported in WAIS-R.36 Although the association between cognitive performance and psychiatric symptoms are consistent in a number of studies, whether there is a causal link between these variables remains unclear.37 Further investigation may provide a comprehensive model for key linkages to cognition and symptoms. In summary, the results obtained in this study are consistent with previous studies of the English version of the WAIS-III in patients with schizophrenia.20,27,33

Letter–Number Sequencing needs a relatively large modification to equalize the cognitive demands among different language users. The cognitive demand for the manipulation of letters is considered to be more complex in the Japanese kana (a twodimensional structure by vowels and consonants, approximately 50 letters) than in the English alphabet (a one-dimensional sequence of phonemes, 26 letters). Consequently, the Japanese version of Letter–Number Sequencing was modified to reduce the level of difficulty by adding extra practice tasks and restricting the types of letters used in the task.23 In the current study, the degree of deficits in Letter– Number Sequencing was similar to that reported in a previous study for English users.33 This result indicates that the Japanese version of Letter–Number Sequencing is adequately adjusted, in terms of difficulty level, compared with the English version. In addition to the WAIS-III, the Letter–Number Sequencing task is also included in the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB). Although the method of Letter– Number Sequencing in the Japanese version of the MCCB partially differs from that of the Japanese version of the WAIS-III, Japanese kana have also been adopted in the MCCB, and the letters have been selected in a similar manner.38 Kaneda et al. preliminarily examined the validity of the Japanese version of the MCCB.39 Further investigation will be needed to adequately validate the Japanese WAIS-III version of Letter–Number Sequencing.

Performance in letter–number sequencing Generally, the WAIS-III subtests are designed in a culture- or language-independent manner and thus require some minor adjustments in translations.

Limitations The present study had several limitations that should be noted. Although all of the patients had FSIQ of 70 or more to exclude the possibility of mental retardation, some patients may have had difficulty completing the WAIS-III. Therefore, the results of the current study might only be relevant to a subgroup of patients with relatively higher-level capacities. Cognitive impairment in patients with schizophrenia can be affected by combining multiple antipsychotic medications, negatively influencing cognition in a dose-dependent manner.40 However, cognitive impairments were also observed in drug-naïve patients with schizophrenia.41 Therefore, cognitive impairment could be a core feature of patients with schizophrenia. This study was cross-sectional, and treatment response and temporal changes in perfor-

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mance were not considered. Future longitudinal studies will be needed to investigate the role of cognitive functioning for the treatment outcome and social functioning. Despite these limitations, this study was the first to examine the performance of schizophrenic patients on the Japanese version of WAIS-III and compare that performance with that of normal controls. The current study has reported the profile of the performance on the Japanese version of WAIS-III in a sizable number of patients with schizophrenia and in healthy control subjects. Analyses of the results indicate that the profile and degree of cognitive impairment of Japanese patients are similar to those of English-speaking patients.

3. Lesh TA, Niendam TA, Minzenberg MJ, Carter CS. Cognitive control deficits in schizophrenia: Mechanisms and meaning. Neuropsychopharmacology 2011; 36: 316– 338. 4. Tomida K, Takahashi N, Saito S et al. Relationship of psychopathological symptoms and cognitive function to subjective quality of life in patients with chronic schizophrenia. Psychiatry Clin. Neurosci. 2010; 64: 62–69. 5. Jabben N, Arts B, van Os J, Krabbendam L. Neurocognitive functioning as intermediary phenotype and predictor of psychosocial functioning across the psychosis continuum: Studies in schizophrenia and bipolar disorder. J. Clin. Psychiatry 2010; 71: 764–774. 6. Mohamed S, Paulsen JS, O’Leary D, Arndt S, Andreasen N. Generalized cognitive deficits in schizophrenia: A study of first-episode patients. Arch. Gen. Psychiatry 1999; 56: 749– 754. 7. Nuechterlein KH, Barch DM, Gold JM, Goldberg TE, Green MF, Heaton RK. Identification of separable cognitive factors in schizophrenia. Schizophr. Res. 2004; 72: 29–39. 8. Reichenberg A, Harvey PD. Neuropsychological impairments in schizophrenia: Integration of performance-based and brain imaging findings. Psychol. Bull. 2007; 133: 833– 858. 9. Meltzer HY, Thompson PA, Lee MA, Ranjan R. Neuropsychologic deficits in schizophrenia: Relation to social function and effect of antipsychotic drug treatment. Neuropsychopharmacology 1996; 14: 27S–33S. 10. Keefe RS, Eesley CE, Poe MP. Defining a cognitive function decrement in schizophrenia. Biol. Psychiatry 2005; 57: 688–691. 11. Keefe RS, Bilder RM, Harvey PD et al. Baseline neurocognitive deficits in the CATIE schizophrenia trial. Neuropsychopharmacology 2006; 31: 2033–2046. 12. Reichenberg A, Harvey PD, Bowie CR et al. Neuropsychological function and dysfunction in schizophrenia and psychotic affective disorders. Schizophr. Bull. 2009; 35: 1022–1029. 13. Schretlen DJ, Cascella NG, Meyer SM et al. Neuropsychological functioning in bipolar disorder and schizophrenia. Biol. Psychiatry 2007; 62: 179–186. 14. Zanelli J, Reichenberg A, Morgan K et al. Specific and generalized neuropsychological deficits: A comparison of patients with various first-episode psychosis presentations. Am. J. Psychiatry 2010; 167: 78–85. 15. Mathews JR, Barch DM. Emotion responsivity, social cognition, and functional outcome in schizophrenia. J. Abnorm. Psychol. 2010; 119: 50–59. 16. Hogarty GE, Flesher S, Ulrich R et al. Cognitive enhancement therapy for schizophrenia: Effects of a 2-year randomized trial on cognition and behavior. Arch. Gen. Psychiatry 2004; 61: 866–876. 17. McGurk SR, Mueser KT, Feldman K, Wolfe R, Pascaris A. Cognitive training for supported employment: 2–3 year

ACKNOWLEDGMENTS We would like to thank all of the individuals who participated in this study. This work was supported in part by research grants from the Japanese Ministry of Health, Labor and Welfare (H22-seishinippan-001); the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) KAKENHI (22390225-Grant-in-Aid for Scientific Research (B), 23659565-Grant-in-Aid for Challenging Exploratory Research and 221S0003-Grant-inAid for Scientific Research on Innovative Areas [Comprehensive Brain Science Network]); and the Japan Foundation for Neuroscience and Mental Health. Additionally, this work was supported by the Strategic Research Program for Brain Sciences (Development of Biomarker Candidates for Social Behavior) of the Ministry of Education, Culture, Sports, Science, and Technology, Japan. No additional external funding was received for this study. The funders had no role in the study design, data collection and analyses, decision to publish, or preparation of the manuscript. All authors declare that they had no conflict of interest.

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SUPPORTING INFORMATION Additional Supporting Information may be found in the online version of this article at the publisher’s web-site: Table S1. Subtests descriptions and indices of the Wechsler Adult Intelligence Scale-III. Table S2. Correlations between clinical variables and Wechsler Adult Intelligence Scale-III subtests in patients with schizophrenia.

© 2014 The Authors Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology

Performance on the Wechsler Adult Intelligence Scale-III in Japanese patients with schizophrenia.

Patients with schizophrenia have been reported to perform worse than non-schizophrenic populations on neuropsychological tests, which may be affected ...
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