Table 3.

Participant demographic and environmental characteristics.

	PD group as a whole	HS group as a whole	p values
Number	86	83	–
Male/female	56/30	38/45	0.018
Age (yrs, mean ± SD)	65.7 ± 0.94	63.7 ± 1.16	0.10
BMI (mean ± SD)	25.32 ± 4.17	25.04 ± 3.34	0.99
Coffee cups/day (mean ± SD)	2.53 ± 0.15	2.66 ± 0.15	0.53
Caffeine intake, mg/day (mean ± SD)	211.69 ± 107.58	217.81 ± 110.18	0.77
Tobacco smoking (n)	9	6	0.34

	Early PD	Age-matched HS	p values
Number	39	39	–
Male/female	15:24	25:14	< 0.01
Age (yrs, mean ± SD)	61.1 ± 7.33	59.6 ± 7.17	0.16
BMI (mean ± SD)	24.33 ± 4.06	24.45 ± 3.20;	0.51
Coffee cups/day (mean ± SD)	2.79 ± 1.34	2.64 ± 1.44	0.72
Caffeine intake, mg/day (mean ± SD)	234.10 ± 104.60	211.89 ± 113.08	0.46
Tobacco smoking	4	3	0.89

	Moderate/advanced PD	Age-matched HS	p values
Number	47	44	–
Male/female	29:18	24:20	0.66
Age (yrs, mean ± SD)	69.71 ± 10.59	67.75 ± 8.00	0.13
BMI (mean ± SD)	26.31 ± 4.11	25.50 ± 3.44	0.47
Coffee cups/day (mean ± SD)	2.32 ± 1.33	2.69 ± 1.29	0.23
Caffeine intake, mg/day (mean ± SD)	193.09 ± 107.55	223.84 ± 108.72	0.25
Tobacco smoking	5	3	0.46