Table 3.

The comparison between different groups

Variable	Mild depression group (a) (n=12)	Moderate depression group (b) (n=13)	Severe depression group (c) (n=16)	Healthy control group (d) (n=33)	p	Post-test†
Age (yr)	16.00±1.54	15.62±1.61	16.44±1.50	16.18±1.10	0.428
Sex, male	7 (58.30)	6 (46.10)	7 (43.70)	15 (45.50)	0.869
Family history of mental disorders, yes	5 (41.70)	8 (61.50)	7 (43.80)	-	0.860
With psychotic symptoms or not, yes	6 (50.00)	8 (61.50)	8 (50.00)	-	0.359
The course of depression (mo)	15.04±10.41	11.38±6.83	25.19±8.38		<0.01**	a-b (0.29)
						a-c (0.004**)
						b-c (<0.01**)
Treatment status					0.873
No previous treatment	4 (33.30)	5 (38.40)	5 (31.25)	-
Received nonstandard treatment	5 (41.70)	5 (38.40)	6 (37.50)		-
Received standard treatment	3 (25.00)	3 (23.20)	5 (31.25)		-
P300
N2 (ms)	263.67±19.15	272.69±26.35	266.94±24.34	240.61±29.76	0.001**	a-b (0.40)
						a-c (0.75)
						a-d (0.01*)
						b-c (0.56)
						b-d (<0.01**)
P3 (ms)	348.58±31.05	351.23±31.12	369.81±31.69	314.64±24.12	<0.01**	c-d (0.002**)a-b (0.82)
						a-c (0.05)
						a-d (0.001**)
						b-c (0.08)
						b-d (<0.01**)
						c-d (<0.01**)
MMN (ms)	204.83±14.74	207.38±18.66	221.38±7.68	177.21±15.98	<0.01**	a-b (0.67)
						a-c (0.005**)
						a-d (<0.01**)
						b-c (0.01*)
						b-d (<0.01**)
						c-d (<0.01**)

Values are presented as mean±standard deviation or number (%). Chi-square test was used to detect the differences of categorical variables between different groups. One-way ANOVA was used to detect the differences of continuous variables between different groups. *p<0.05; **p<0.01; †pairwise comparisons were adjusted for multiple testing using LSD correction. ANOVA, analysis of variance; LSD, least significant difference; MMN, mismatch negativity