Table 1.

Participant demographics.

Variable	Unit	Cases (N = 317)c	Controls (N = 676)c	P-value
Agea	Years (mean, SD)	57.4 (10.1)	60.8 (9.8)	<0.01
Sexb	Males (N)	72	265	<0.01
	Females (N)	245	411
Study siteb	Aberdeen	122	361	<0.01
	Dundee	195	315
Hair processing batchb	Batch 1	228	506	0.367
	Batch 2	89	170
Total QIDS scorea	Mean (SD)	7.04 (4.9)	3.6 (2.3)	<0.01

^aWilcoxon t-test.

^bChi-squared test.

^cCalculated by SCID diagnosis.