Table 1.

Gender differences in onset ages, quantity/frequency, and outcomes of substance use (N = 320)

	Female	Male
Variable	M (SD) or %	M (SD) or %
Onset age of alcohol use, years	14.57 (3.21)*	13.55 (4.34)*
Onset age of nicotine use, years	14.71 (3.11)	15.08 (3.68)
Onset age of marijuana use, years	15.96 (2.99)	15.68 (3.49)
Early adolescence: ages 10–14.99
Average number of drinking days per montha	0.15 (0.39)	0.24 (0.92)
Average number of drinks per drinking daya	0.21 (0.82))	0.27 (0.89)
Frequency of nicotine use in past 12 monthsa,b	0.25 (0.64)	0.31 (0.79)
Frequency of marijuana use in past 12 monthsa,c	0.10 (0.40)	0.30 (0.99)
Number of alcohol problemsa	0.18 (0.55)	0.16 (0.53)
DSM-IV alcohol use disorder diagnosisd	12%	8%
Late adolescence: ages 15–17.99
Average number of drinking days per montha	1.61 (2.60)	1.38 (2.22)
Average number of drinks per drinking daya	1.86 (2.08)*	2.59 (3.84)*
Frequency of nicotine use in past 12 monthsa,b	0.98 (1.35)	0.74 (1.23)
Frequency of marijuana use in past 12 monthsa,c	1.13 (1.75)	1.21 (2.00)
Number of alcohol problemsa	1.41 (2.14)	1.14 (1.85)
DSM-IV alcohol use disorder diagnosisd	39%	45%
Young adulthood: ages 18 and older
Average number of drinking days per montha	4.41 (4.16)*	7.20 (5.59)*
Average number of drinks per drinking daya	3.46 (2.54)*	5.85 (4.03)*
Frequency of nicotine use in past 12 monthsa,b	1.38 (1.62)	1.56 (1.59)
Frequency of marijuana use in past 12 monthsa,c	1.37 (2.11)*	2.34 (2.56)*
Number of alcohol problemsa	2.41 (2.94)*	3.37 (3.03)*
DSM-IV alcohol use disorder diagnosisd	38%*	69%*

Notes: DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition.

^aThe repeated measures within individuals were averaged across waves in the developmental period;

^bthe frequency of nicotine use in the past 12 months was a 0–4 scale (0 = never; 1 = once or twice; 2 = occasionally but not regularly; 3 = regularly for a while, but not now; 4 = regularly now);

^cthe frequency of marijuana use in the past 12 months was a 0–7 scale (0 = none, 1 = 1–2 occasions, 2 = 3–5 occasions, 3 = 6–9 occasions, 4 = 10–19 occasions, 5 = 20–39 occasions, 6 = 40–99 occasions, 7 = ≥100 occasions);

^dthe participant met an alcohol use disorder diagnosis in any of the years in the developmental period.

^*Significant gender difference (p < .05).