Genetic Influence on Substance Use Comorbidity Peaked in Adolescence and Declined Into Adulthood
A twin study tracking 3,762 participants from age 11 to 29 found that the shared genetic risk driving co-occurring nicotine, alcohol, and marijuana problems was strongest in adolescence and declined with age as environmental factors became more important.
Quick Facts
What This Study Found
Researchers followed twins from age 11 through 29, measuring nicotine, alcohol, and marijuana dependence symptoms at six timepoints. During adolescence (ages 14-17), the co-occurrence of symptoms across all three substances was strongly driven by a common genetic factor. This means that adolescent substance problems tend to be generalized rather than substance-specific.
As participants aged into their 20s, the influence of this shared genetic factor declined substantially. By age 24-29, substance dependence symptoms were increasingly driven by substance-specific factors, particularly nonshared environmental influences. Substance use became more specialized and less governed by a general vulnerability.
Key Numbers
3,762 twins assessed at 6 timepoints (ages 11-29). Substance symptoms peaked around age 20 and declined by age 29. Shared genetic influence was highest at ages 14-17 and declined from 17 to 24. Environmental influences increased with age.
How They Did This
Community-representative twin sample (N=3,762) assessed at ages 11, 14, 17, 20, 24, and 29. Nicotine, alcohol, and marijuana abuse/dependence symptom counts were modeled using a single common factor at each age. Changes in factor loadings and genetic/environmental contributions were tested across timepoints.
Why This Research Matters
This study explains why adolescent substance use tends to be general (teens who use one substance often use others) while adult substance use becomes more specialized. The shift from shared genetic risk to specific environmental influences has direct implications for when and how to intervene.
The Bigger Picture
This landmark study resolves a puzzle in addiction research. In adolescence, generalized prevention (targeting all substance use broadly) makes sense because a common genetic factor drives involvement across substances. In adulthood, substance-specific interventions become more appropriate because each substance is increasingly influenced by its own environmental and genetic factors.
What This Study Doesn't Tell Us
The community-representative sample may underrepresent individuals with severe substance use disorders who are difficult to retain in long-term studies. Symptom counts may not capture the full clinical picture of dependence. The twin modeling approach makes assumptions about equal environments for identical and fraternal twins.
Questions This Raises
- ?What specific environmental factors drive the substance-specific patterns in adulthood?
- ?Could identifying adolescents with high generalized genetic risk enable earlier, more targeted prevention?
- ?Does the genetic architecture shift similarly for other substances not studied here?
Trust & Context
- Key Stat:
- Shared genetic influence peaked at ages 14-17 and declined substantially by age 24
- Evidence Grade:
- Large community-representative twin study with six longitudinal assessments spanning 18 years; strong evidence.
- Study Age:
- Published in 2012. This developmental perspective on substance use genetics has influenced prevention science.
- Original Title:
- Decline in genetic influence on the co-occurrence of alcohol, marijuana, and nicotine dependence symptoms from age 14 to 29.
- Published In:
- The American journal of psychiatry, 169(10), 1073-81 (2012)
- Authors:
- Vrieze, Scott I, Hicks, Brian M(2), Iacono, William G(6), McGue, Matt
- Database ID:
- RTHC-00633
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Why do teens tend to use multiple substances?
This study found that in adolescence, a common genetic factor drives involvement across nicotine, alcohol, and marijuana. Teens with this generalized vulnerability tend to experiment with multiple substances rather than gravitating toward just one. As they age, substance use patterns become more specialized and driven by substance-specific environmental factors.
Does this mean genetics matter less for adult substance use?
Not exactly. The total genetic influence does not necessarily decline, but it shifts from being shared across substances (generalized risk) to being more substance-specific. An adult who develops alcohol problems may have genetic factors specific to alcohol rather than a generalized addiction vulnerability.
Read More on RethinkTHC
- cannabis-dependence-physical-psychological-addiction-science
- cannabis-perception-vs-evidence-gap
- cannabis-use-disorder-test
- cross-addiction-quit-weed-start-drinking
- is-weed-addictive
- is-weed-addictive-science
- quitting-weed-and-alcohol
- rehab-for-weed-addiction-necessary
- signs-of-cannabis-use-disorder
- weed-vape-pen-addiction
Cite This Study
https://rethinkthc.com/research/RTHC-00633APA
Vrieze, Scott I; Hicks, Brian M; Iacono, William G; McGue, Matt. (2012). Decline in genetic influence on the co-occurrence of alcohol, marijuana, and nicotine dependence symptoms from age 14 to 29.. The American journal of psychiatry, 169(10), 1073-81.
MLA
Vrieze, Scott I, et al. "Decline in genetic influence on the co-occurrence of alcohol, marijuana, and nicotine dependence symptoms from age 14 to 29.." The American journal of psychiatry, 2012.
RethinkTHC
RethinkTHC Research Database. "Decline in genetic influence on the co-occurrence of alcohol..." RTHC-00633. Retrieved from https://rethinkthc.com/research/vrieze-2012-decline-in-genetic-influence
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.