Table 1.

Distribution of first occurrences of adversity, substance use, and substance-use-disorder (SUD) symptoms in the American Indian Service Utilization, Psychiatric Epidemiology, Risk and Protective Factors Project sample

	Ever experienced (lifetime exposure)			Experienced before age 18
Variable	n	% of sample	Mean age at first exposure	n	% of those with lifetime exposure
Any adversitya	2,002	68.4	7.2	1,855	92.7
Major childhood event	1,493	51.0	7.3	1,445	96.8
Trauma	668	22.8	11.9	533	79.8
Witnessed violence	791	27.0	11.2	695	87.9
Traumatic news	325	11.1	15.8	232	71.4
Death of significant otheb	599	20.5	17.0	364	60.8
Substance use	2,503	85.5	15.2	1,921	76.7
SUD	1,061	36.2	19.7	491	46.3

^aFor adversity, occurrence subsequent to onset of substance use was counted as no occurrence;

^bonly deaths of immediate family members—parents and siblings—were included in this category; more normative experiences with significant deaths, such as those of aging grandparents, were excluded here.