TABLE 1.

Demographic data from patient and control group.

Variables	Patients	Controls	Statistics
	N = 130	N = 129	t	p
Age1	38 ± 11.3	38.1 ± 11.7	−0.103	0.918
Gender (m/f)2	74/56	74/55	χ2 = 0.005	0.934
Education degree1	4.5 ± 1.5	5.3 ± 1.2	−5.084	0.000

Between group comparison: ¹t-test for independent samples (two-tailed): mean ± standard deviation; ²χ²-test.

Educational degree categories: (0), none; (1), Grades 1–9; (2), Grades 10–11; (3), High school graduate; (4), Some college; (5), College graduate; (6), more than college degree.