Table 1. Demographic Characteristics and Smoking Behavior.

	Smokers				Nonsmokers
	Control (n=104)		rMDD (n=42)		Control (n=22)		rMDD (n=30)
	M	SD	M	SD	M	SD	M	SD	F	p
Age*** (years)	46.5	10.2	45.3	10.5	29.8	13.1	29.0	10.5	32.52	<0.001
Education*** (years)	14.2	1.9	14.0	1.7	17.0	2.1	15.4	2.7	15.83	<0.001
Expired CO	17.6	7.8	17.1	7.2	—	—	—	—	0.12	0.73
Time since last cigarette (h)	1.8	0.8	2.0	0.8	—	—	—	—	1.69	0.20
Cigarettes today#	6.8	3.9	7.8	5.6	—	—	—	—	1.72	0.19
Cigarettes yesterday#	18.3	10.1	19.3	8.6	—	—	—	—	0.25	0.61
Mean cigarettes per day#	19.7	7.2	18.9	8.2	—	—	—	—	0.32	0.57
Age began steady smoking*	17.0	3.9	15.7	2.7	—	—	—	—	3.94	0.05
Years regular smoking	27.1	10.7	26.3	10.2	—	—	—	—	0.22	0.67
FTND	5.0	2.1	5.4	2.0	—	—	—	—	1.00	0.31
HAM-D	2.68	3.15	3.20	2.59	—	—	—	—
BDI**	—	—	—	—	1.68	1.76	3.90	3.80

Abbreviations: BDI, Beck Depression Inventory; CO, carbon monoxide; FTND, Fagerstrom test for nicotine dependence total score; HAM-D, Hamilton Rating Scale for Depression; rMDD, remitted major depressive disorder.

For age and education, statistics were calculated across all four groups, while the remaining smoking-related variables were compared only between the smokers. Smokers were significantly older than nonsmokers, and had also completed fewer years of education, ***p<0.001. Smokers with a past history of depression began smoking at a significantly younger age than those without a history of depression, *p=0.05. HAM-D and BDI scores represent raw values, while the statistics were conducted on the transformed Z-scores to allow for the comparison across measure type. Despite all scores falling in a normal range, nonsmokers with rMDD had significantly higher depression scale scores compared to control nonsmokers t(50)=2.54, **p=0.01.