Half of Substance Use Initiation Occurs in the First 2 Decades of Life

Substance use initiation occurs within the first 2 decades of life in 50% of cases, although age varies by specific substance; although most risk factors for substance use are shared, some are substance-specific, according to the results of a study published in The American Journal on Addiction.

Although much research has been done on the risk factors involved in substance use initiation, important questions remain. The evidence regarding ethnicity as a risk factor is inconsistent, and although psychiatric illness is accepted as a risk factor, detailed examination of the contribution of specific psychiatric disorders toward substance use or toward specific substance use is lacking.

Carolos Blanco, MD, PhD, of the Department of Psychiatry, New York State Psychiatric Institute/Columbia University (New York, New York), and the Division of Epidemiology, Services, and Prevention Research, National Institute on Drug Abuse in Bethesda, Maryland, and colleagues analyzed data from Wave 1 participants in the National Epidemiological Survey of Alcohol and Related Conditions (NESARC), representing a population of 43,093 individuals. The investigators obtained separate estimates of cumulative probability of substance use initiation for nicotine, alcohol, cannabis, and cocaine. They used survival analyses with time-varying covariates to identify risk factors for substance initiation.

The likelihood of initiating use of a substance over a lifetime was 45.5% for nicotine, 82% for alcohol, 19.6% for cannabis, and 6.4% for cocaine. Among study participants who developed a lifetime use of nicotine, 50% had initiated use by age 15.3 years. Age of initiation was older for the other substances — 17.8 years for alcohol, 16.6 years for cannabis, and 19.8 years for cocaine. Factors associated with risk for use of all substances assessed included previous use of another substance, male sex, having a cluster B personality disorder, family history of substance use disorder (SUD), and being separated, divorced, or widowed.

Individuals who were black, Hispanic, and Asian were less likely than white individuals to use nicotine. Although black and Asian individuals had a lower probability of lifetime alcohol use than white individuals, Hispanic people had a higher probability. And, in comparison with the white population, the black population had a lower probability and the Hispanic community had a higher probability of initiating use of cocaine.

The presence of major depressive disorder increased the risk for alcohol and cannabis use, whereas bipolar disorder was associated with a higher probability of cannabis use but a lower probability of nicotine use. Social anxiety disorder or specific phobia increased the risk for cannabis use, and individuals with specific phobia were more likely to use nicotine. Cluster B personality disorder increased the risk for all of the substances assessed, but cluster A personality disorder was associated with nicotine use, and cluster C personality disorder increased the risk for alcohol use. A history of a conduct disorder increased the likelihood of alcohol and cannabis use. A family history of SUD increased the risk for all substances assessed.

The authors expressed the hope that identification and targeting of risk factors for substance initiation may help decrease the burden of SUD.

Reference

Blanco C, Flórez-Salamanca L, Secades-Villa R, Wang S, Hasin DS. Predictors of initiation of nicotine, alcohol, cannabis, and cocaine use: results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Am J Addict. 2018. 27:477-484.