A systematic review of 38 longitudinal studies found that delayed executive functioning and emotional perception may predispose adolescents to substance use, while use itself causes further functional, structural, and cognitive deficits.
Adolescent health specialists, neurodevelopmental researchers, substance use prevention program designers
38 longitudinal studies spanning neuroimaging, neurophysiology, and neuropsychology
What the researchers found
High-quality evidence showed that delayed or irregular neurodevelopment in executive functioning, particularly emotional perception, may predispose young people to higher frequency substance use. The review also found evidence of functional, structural, and cognitive deficits following substance use, with harm potentially dependent on frequency and recovery potentially dependent on duration of use.
Why it matters
Separating what comes before substance use (predisposing brain differences) from what comes after (use-caused damage) is essential for designing effective prevention. If certain neurodevelopmental patterns predict who will use substances, early identification and intervention become possible.
The numbers in context
38 longitudinal studies included; 22 neuroimaging studies, 2 neurophysiological, 22 neuropsychological; age range 10-25 years; five databases searched
How the study worked
Systematic review searching five databases for longitudinal studies examining neuropsychological, neuroimaging, or neurophysiological predictors and consequences of cannabis and illicit substance use in individuals aged 10-25. Yielded 38 eligible studies covering 22 neuroimaging, 2 neurophysiological, and 22 neuropsychological findings.
What this study cannot tell us
Heterogeneous study designs and measures across the 38 included studies. Most studies combined cannabis with other substances, making it difficult to isolate cannabis-specific effects. Longitudinal designs varied in follow-up duration.
How to read the evidence
Systematic review of longitudinal studies published in a high-impact journal (The Lancet Child & Adolescent Health), providing strong evidence for the bidirectional relationship.
When this study was published
Published in 2021.
The bigger picture
The bidirectional relationship between brain development and substance use creates a potential vicious cycle: developmental differences increase vulnerability to use, and use further disrupts development. Breaking this cycle requires addressing both the predisposing factors and the substance use itself.
Questions still open
- Can early screening for executive functioning delays identify at-risk youth before substance initiation? How much recovery is possible after cessation, and what determines the extent of recovery?
Common questions
Do brain differences come before or after substance use?
Can the brain recover after stopping?
Read the original research
Neuropsychological and neurophysiological predictors and consequences of cannabis and illicit substance use during neurodevelopment: a systematic review of longitudinal studies.
The Lancet. Child & adolescent health, 5(8), 589-604
Citation
Debenham, Jennifer; Birrell, Louise; Champion, Katrina; Lees, Briana; Yücel, Murat; Newton, Nicola. (2021). Neuropsychological and neurophysiological predictors and consequences of cannabis and illicit substance use during neurodevelopment: a systematic review of longitudinal studies.. The Lancet. Child & adolescent health, 5(8), 589-604. https://doi.org/10.1016/S2352-4642(21)00051-1
Explore the wider topic
- How to Talk to Your Teenager About Weed (Without Losing Them)
- My Kid's Friends Smoke Weed: A Parent's Guide
- I Smoke Weed But Don't Want My Kids To: Navigating the Hypocrisy
- Quitting Weed as a Parent: Why It Is the Hardest and Most Important Quit
- Quitting Weed as a Teen or Young Adult
- My Kid Is Smoking Weed: A Parent's Guide