Twin study identified five drug use patterns in mid-adulthood, with persistent polydrug use being highly heritable
Latent class analysis of 3,785 Australian twins identified five drug use typologies, with persistent polydrug use showing 94% heritability and distinct risk profiles from persistent prescription misuse.
Quick Facts
What This Study Found
Five drug use classes emerged: no/low use (50%), desistant cannabis use (23%), desistant party drug use (18%), persistent prescription drug misuse (4%), and persistent polydrug use (5%). Persistent polydrug use was highly heritable (a2 = 0.94) and associated with conduct disorder (OR = 2.40) and antisocial personality disorder (OR = 3.27). Persistent prescription misuse was linked to depression (OR = 2.38) and lifetime suicide attempt (OR = 2.31).
Key Numbers
3,785 twins/siblings (1,365 men, 2,420 women; mean age 32); five classes: 50% no/low, 23% desistant cannabis, 18% desistant party drug, 4% persistent prescription, 5% persistent polydrug; MZ concordance k=0.30-0.35 vs DZ k=0.19-0.20; polydrug heritability a2=0.94
How They Did This
Latent class analysis applied to self-reported current and past drug use data from 3,785 twins and siblings (mean age 32) in the Australian Twin Registry Cohort III. Biometric modeling compared monozygotic and dizygotic twin concordances. Logistic regression examined associations with psychiatric disorders.
Why This Research Matters
Identifying distinct trajectories of drug use with different genetic contributions and psychiatric correlates could improve targeted prevention and treatment approaches rather than treating all substance use as a single phenomenon.
The Bigger Picture
The high heritability of persistent polydrug use (94%) and its distinct risk profile from persistent prescription misuse suggest these are fundamentally different conditions with different biological and environmental drivers, challenging one-size-fits-all approaches to substance use treatment.
What This Study Doesn't Tell Us
Cross-sectional with retrospective recall of past use, which approximates but does not substitute for true longitudinal data. Australian sample may not generalize globally. Self-reported substance use. Small sizes for the persistent use classes (4-5%).
Questions This Raises
- ?What specific genetic variants drive the high heritability of persistent polydrug use?
- ?Could the desistant cannabis class (23%) represent a normative developmental pattern rather than a clinical concern?
Trust & Context
- Key Stat:
- 94% heritability for persistent polydrug use pattern
- Evidence Grade:
- Large genetically-informed twin sample with sophisticated statistical methods, though cross-sectional recall limits causal inference.
- Study Age:
- Published in 2021 using Australian Twin Registry data.
- Original Title:
- Typologies of illicit drug use in mid-adulthood: a quasi-longitudinal latent class analysis in a community-based sample of twins.
- Published In:
- Addiction (Abingdon, England), 116(5), 1101-1112 (2021)
- Authors:
- Dash, Genevieve F(2), Martin, Nicholas G(18), Agrawal, Arpana(39), Lynskey, Michael T, Slutske, Wendy S
- Database ID:
- RTHC-03086
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
What does "desistant" mean in this context?
Desistant refers to drug use that occurred in the past but was discontinued by the time of the study. The desistant cannabis class (23%) and desistant party drug class (18%) both represent people who previously used but stopped.
How did persistent polydrug use differ from persistent prescription misuse?
Polydrug users had higher rates of cannabis and stimulant use disorder (OR = 6.14-28.01), younger first substance use, more drug-using peers, and more drug use opportunities. Prescription misusers had higher rates of depression and suicide attempts.
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Cite This Study
https://rethinkthc.com/research/RTHC-03086APA
Dash, Genevieve F; Martin, Nicholas G; Agrawal, Arpana; Lynskey, Michael T; Slutske, Wendy S. (2021). Typologies of illicit drug use in mid-adulthood: a quasi-longitudinal latent class analysis in a community-based sample of twins.. Addiction (Abingdon, England), 116(5), 1101-1112. https://doi.org/10.1111/add.15225
MLA
Dash, Genevieve F, et al. "Typologies of illicit drug use in mid-adulthood: a quasi-longitudinal latent class analysis in a community-based sample of twins.." Addiction (Abingdon, 2021. https://doi.org/10.1111/add.15225
RethinkTHC
RethinkTHC Research Database. "Typologies of illicit drug use in mid-adulthood: a quasi-lon..." RTHC-03086. Retrieved from https://rethinkthc.com/research/dash-2021-typologies-of-illicit-drug
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.