Age-associated decrease in global DNA methylation in patients with major depression

Figures & data

Figure 1 Subject recruitment procedure in current study.

Abbreviations: CHQ, Chinese Health Questionnaire; DSM-IV-TR, Diagnostic and Statistical Manual of Mental Disorders 4th edition text revision; HAM-D, Hamilton Rating Scale for Depression; MDD, major depressive disorder.

Table 1 Demographic and clinical characteristics of subjects included in current study

	Healthy controls (n=25)	Severe MDD patients (n=24)	Remitted MDD patients (n=25)	P-value
Sex proportion (% of females)	44.0	70.8	64.0	0.104a
Age (years)	48.3±11.1	45.9±11.5	49.2±13.2	0.614b
Years of education (years)	14.6±3.3	10.2±4.1	9.4±5.2	<0.001b
BMI (kg/m^2)	23.8±3.7	24.6±3.6	23.5±4.2	0.579b
Onset of illness (years)	NA	35.8±12.2	43.7±12.7	0.031c
Duration of illness (months)	NA	100.8±101.1	66.2±53.1	0.152c
HAM-D	NA	25.5±4.4	3.0±2.1	<0.001c
Imipramine equivalence (mg)	NA	120.1±43.9	126.0±55.8	0.736c
Chlorpromazine equivalence (mg)	NA	247.6±191.3	51.7±31.4	0.035c
Previous suicide history (%)	NA	50.0	16.0	0.025a
Family history of psychiatric disorder (%)	NA	45.8	32.0	0.484a
Family history of suicidal behavior (%)	NA	20.8	20.0	0.777a
5-methylcytosine (%)	1.45±0.61	1.15±0.32	1.35±0.31	0.053b
5-hydroxymethylcytosine (%)	2.05±1.02	1.44±0.49	1.45±0.45	0.004b

Notes: Data are shown as mean ± standard deviation.

a Chi-square test.

b One-way ANOVA test.

c Independent-sample t-test.

Abbreviations: BMI, body mass index; HAM-D, Hamilton Depression Rating Scale; MDD, major depressive disorder; NA, not applicable.

Figure 2 (A) 5-methylcytosine (5-mc) and (B) 5-hydroxymethylcytosine (5-hmc) levels in patients with severe major depressive disorder (MDD), remitted MDD, and healthy controls, divided by sex (n=30 in males and n=44 in females).

Notes: The error bars are shown as standard deviations. The asterisks express significant difference from controls. *P<0.05, and **P<0.01.

Figure 3 (A) 5-methylcytosine (5-mc) and (B) 5-hydroxymethylcytosine (5-hmc) levels in patients with severe major depressive disorder (MDD), remitted MDD, and healthy controls, in different age groups (n=14 for younger group, n=29 for middle-age group, and n=31 for older age group).

Notes: Stratification of age groups are as follows: equal to or below 35 years of age, between 36 years and 50 years, and over 50 years. The error bars are shown as standard deviations. The asterisks denote significant difference from controls. *P<0.05 and **P<0.01.

Figure 4 Scatterplots of the correlation between (A) 5-methylcytosine (5-mc) levels, and (B) 5-hydroxymethylcytosine (5-hmc) levels and the severity of depressive symptoms shown as HAM-D.

Notes: Pearson’s correlation r=−0.360, P=0.011 for 5-mc and r=−0.058, P=0.690 for 5-hmc.
Abbreviation: HAM-D, Hamilton Depression Rating Scale.