Table 1.

Characteristics of study participants

	Controls		MDD		Test
	Mean	SD	Mean	SD	P value
a) Discovery phase
Blood MWAS Sample	n = 320		n = 812
Sex	0.591	0.492	0.667	0.471	0.018
Age	41.61	14.64	41.53	12.25	0.912
EDU	13.13	3.158	11.46	3.198	<0.001
IDS	5.022	3.533	33.79	10.94	<0.001
TCA	0.000	0.000	0.048	0.214	<0.001
SSRI	0.003	0.056	0.299	0.458	<0.001
Other AD	0.000	0.000	0.112	0.315	<0.001
CD3	0.296	0.086	0.281	0.087	0.008
CD14	0.113	0.028	0.109	0.028	0.049
CD15	0.509	0.115	0.536	0.114	<0.001
CD19	0.082	0.034	0.074	0.033	<0.001
b) Overlap phase
Brain MWAS Sample*	n = 31		n = 30
Sex	0.581	0.502	0.567	0.504	1
Age	51.77	17.66	51.43	18.59	0.942
PMI	46.3	14.97	41.49	15.65	0.224
pH	6.304	0.217	6.482	0.273	0.009
c) Replication phase
BA10 Brain Collection A	n = 37		n = 44
Sex	0.297	0.463	0.409	0.497	0.416
Age	61	18.64	55	20.57	0.176
PMI	21.77	16.78	32.08	25.07	0.047
pH	6.605	0.223	6.595	0.183	0.822
BA10 Brain Collection B	n = 25		n = 39
Sex	0.36	0.49	0.308	0.468	0.871
Age	61.48	15.02	47.9	16.94	0.002
PMI	39.22	25.57	48.58	26.39	0.166
pH	6.534	0.238	6.648	0.315	0.212
Validation in BA25 included the participants described in section b (see above).

Note: n is number of samples left after quality control. Sex indicates the proportion of males, age is measures in years. EDU years of education. The IDS (Inventory of Depressive Symptomatology) is a self-report measure of symptom severity. The usage of antidepressants is indicated for TCA (tricyclic antidepressant), SSRI (serotonin reuptake inhibitor) and other AD (antidepressant). The estimated blood cell type proportions are indicated by CD3 (T-lymphocytes), CD14 (monocytes), CD15 (granulocytes) and CD19 (B-lymphocytes). PMI (postmortem interval) is measured in hours. * The numbers given are for the participants contributing BA10 tissue. For BA25, while the number of cases remained the same, the number of control participants was 30.