Table 1.

Demographic characteristics of participants.

	MDD		HC		Statistical values
	Mean	SD	Mean	SD
Sex (m/f)	17/17		36/42		${\chi }_{(1)}^2$ = 0.141; p = 0.71
Age (years)	37.4	9.9	37.3	7.2	t(110) = 0.093; p = 0.93
Education (years)	15.7	2.2	15.1	2	t(101) = 1.357; p = 0.18
eIQ	112	8	107.5	9.3	t(110) = 2.440; p = 0.02
CESD	20	14	8.1	5.2	$t_{(29.7)}^{\ast }$= 4.391; p < 0.001
SSS	2.74	0.51	2.54	0.73	$t_{(88.3)}^{\ast }$= 1.631; p = 0.11
HAMD	7.12	6.29
GAF	57.4	16.4
IMP	96.5	151.9
CP	48.1	105.1
DZP	4.9	8.7

MDD, major depressive disorder; HC, healthy control; SD, standard deviation; m: male; f, female; eIQ, estimated (premorbid) intelligence quotient; SSS, Stanford sleepiness scale; HAMD, 17-item Hamilton rating scale for depression; CESD, Center for Epidemiologic Studies depression scale; GAF, global assessment of functioning; IMP, imipramine equivalent of antidepressant dosage; CP, chlorpromazine equivalent for antipsychotic dosage; DZP, diazepam equivalent for anxiolytic dosage.

*The degrees of freedom were adjusted for CESD and SSS because the equality of variances between the groups was rejected.