Table 1.

Demographic and clinical characteristics of study groups.

Variable	Mean (SD) [range]		dfa	t test or χ2 values	p value
	Schizophrenic patients (n = 50)	Healthy control subjects (n = 50)
Age (years)	40.6 (10.4) [18–57]	40.8 (9.4) [19–56]	1, 98	0.10	0.92
Gender
Male/female	45/5	45/5	1	0.00	1.00
Handednessb	0.78 (0.20) [0.1–1.0]	0.80 (0.17) [0.4–1.0]	1, 94	0.50	0.62
Socioeconomic statusc
Subject's own	3.9 (1.0)	2.4 (1.1)	1, 94	6.64	<0.0001**
Parental	3.0 (1.2)	2.7 (1.2)	1, 94	1.30	0.20
Education (school years)	13.0 (1.8)	14.9 (2.2)	1, 95	4.92	<0.0001**
MMSE	28.6 (1.5)	29.4 (0.8)	1, 94	3.43	0.001**
WAIS-III Verbal IQ	93.9 (13.7)	107.6 (14.8)	1, 71	4.10	0.0001**
WAIS-III Peformance IQ	86.2 (11.5)	106.5 (17.4)	1, 70	5.89	<0.0001**
Symptom onset (years)	21.3 (4.6), n = 43	NA
Duration of illness (years)	19.5 (11.2), n = 42	NA
Antipsychotic medication dosaged	432.0 (185.6), n = 40	NA
PANSS (total score)	76.8 (23.7), n = 43	NA

^*P<0.05,

^**P<0.01.

MMSE = Mini-Mental State Examination (Folstein et al., 1975); WAIS-III = Wechsler Adult Intelligence Scale—3rd Edition (Wechsler, 1997); IQ = intelligence quotient; PANSS = Positive and Negative Syndrome Scale (Kay et al., 1987); NA = data not applicable.

^aThe degrees of freedom (df) differ among variables owing to missing data for some participants.

^bHandedness was evaluated using the Edinburgh inventory and right-handedness is above 0.

^cHigher scores indicate lower socioeconomic status (Hollingshead, 1965).

^dChlorpromazine equivalent (mg).