Table 1. Demographic Characteristics of Subjects Stratified into Low and High P50 and PPI Subgroups.

	Study cohort 1						Study cohort 2						Study cohort 3
	Mean	SE	Mean	SE	F/χ2a	P-value	Mean	SE	Mean	SE	F/χ2a	P-value	Mean	SE	Mean	SE	F/χ2a	P-value
	Low P50 subgroup (n=14)		High P50 group (n=14)		Main effect of group		Low P50 subgroup (n=15)		High P50 subgroup (n=15)		Main effect of group		Low P50 subgroup (n=15)		High P50 subgroup (n=15)		Main effect of group
Age (years)	22.64	0.82	24.36	0.94	1.88	0.18	25.87	1.80	25.33	1.10	0.06	0.80	25.73	1.26	25.07	1.30	0.14	0.72
BMI	22.43	0.45	23.11	0.53	0.94	0.34	23.10	0.80	22.43	0.48	0.51	0.48	23.07	0.44	22.77	0.60	0.16	0.69
IQ (MWT-B)	110.93	3.09	117.36	2.99	2.24	0.15	111.00	2.43	107.80	1.32	1.34	0.26	112.27	3.03	111.13	2.62	0.08	0.78
Smokers	4		5		0.16	0.50	3		5		0.68	0.34	6		4		0.60	0.35

	Low PPI subgroup (n=14)		High PPI subgroup (n=14)		Main effect of group		Low PPI subgroup (n=15)		High PPI subgroup (n=15)		Main effect of group		Low PPI subgroup (n=15)		High PPI subgroup (n=15)		Main effect of group
Age (years)	23.35	0.82	23.85	1.06	0.14	0.72	24.00	1.58	26.67	1.37	1.62	0.21	23.87	0.88	27.07	1.57	3.28	0.08
BMI	23.17	0.45	22.18	1.91	2.06	0.16	22.55	0.77	22.76	0.57	0.05	0.83	22.85	0.50	23.12	0.57	0.13	0.72
IQ (MWT-B)	115.71	3.38	111.69	2.94	0.79	0.38	112.87	1.85	107.45	1.80	4.36	0.04	110.87	2.49	111.71	3.24	0.04	0.84
Smokers	4		5		0.16	0.50	3		5		0.68	0.34	6		4		0.60	0.35

Significant p-values are shown in bold.

^aThe χ² test for smoking data.