Table 1.

Rates for Major Depressive Disorder and Nicotine Dependence at 15, 18, and 21 Years by Gender and Diagnostic Status of Other Disorder and Means and Standard Deviations by Gender

	% Diagnoses			% Dx for Youth with Other Dx / % Dx for Youth without Other Dx			Symptom Counts M (SD)
	Males & Females	Male	Female	Males & Females	Male	Female	Males & Females	Male	Female
NicD
15 years	7.4	7.6	7.2	23.4 / 6.9	23.8 / 7.2	23.1 / 6.6	.31 (1.08)	.31 (1.05)	.31 (1.10)
18 years	23.0	28.4	17.8	34.8 / 21.4	50.0 / 26.8	30.0 / 16.0	.88 (1.65)	1.07 (1.78)	.70 (1.51)
21 years	28.1	37.0	20.2	38.5 / 26.7	52.3 / 34.9	28.6 / 18.8	1.13 (1.77)	1.53 (1.95)	.78 (1.50)
MDD
15 years	3.4	3.0	3.7	10.6 / 2.8	9.4 / 2.5	11.8 / 3.0	.30 (1.13)	.24 (1.05)	.35 (1.21)
18 years	7.3	3.6	10.7	11.3 / 6.1	6.5 / 2.5	18.3 / 9.1	.53 (1.61)	.31 (1.20)	.74 (1.88)
21 years	12.3	10.6	13.9	16.8 / 10.5	15.1 / 8.0	19.7 / 12.4	.81 (2.04)	.71 (1.89)	.90 (2.16)

Notes. Rates and symptom counts at 15 years are lifetime until age 15 and at 18 and 21 years are since the pervious assessment (approximately the preceding 3 years). Dx = diagnoses. NicD=nicotine dependence. MDD=major depressive disorder. Columns under the center heading give the rate of the indicated disorder in individuals with the other disorder compared to the rate in those without the other disorder. For instance, 23.4% of depressed 15-year-olds were nicotine dependent, and 6.9% of non-depressed 15-year-olds were nicotine dependent.