Rats exposed to weekend-like binges of alcohol and cannabinoids plus daily nicotine during adolescence showed lasting impairments in motivation-based learning in adulthood, with females showing effects earlier than males.
Parents, educators, and researchers concerned about the effects of adolescent polydrug use
Females affected earlier than males
What the researchers found
Female rats showed impaired food-reward learning on both easy (FR1) and harder (FR2) tasks, while males showed impairment only on the harder FR2 task. Treated females also had a significantly lower percentage of learners than controls. Both sexes showed reduced motivation for natural rewards in adulthood, suggesting polydrug exposure during adolescence disrupts reward processing.
Why it matters
This is one of the first studies to model the realistic pattern of adolescent polydrug use: daily cigarettes combined with weekend alcohol and cannabis binges. The finding that this combination causes lasting motivational deficits is relevant to the millions of teenagers who use these substances together.
The numbers in context
20 male and 20 female rats; exposure from postnatal day 30-60; testing after day 90; treated females impaired on FR1 and FR2; treated males impaired on FR2 only; treated females had fewer learners than controls
How the study worked
Adolescent Long-Evans rats (20 male, 20 female) from postnatal day 30-60 received daily nicotine (0.3 mg/kg i.p.) plus twice-weekly "binge day" alcohol (3 g/kg intragastric) and WIN55,212-2 (1.2 mg/kg i.p.). Tested after day 90 on food-rewarded operant learning (FR1 for 6 days, then FR2 after 42-day rest).
What this study cannot tell us
Animal model with specific drug doses and routes that differ from human use patterns. Single dose level of each substance tested. Operant learning in rats may not perfectly model human motivation. No individual drug groups to determine which substance or combination drives the effects.
How to read the evidence
Novel polydrug design modeling realistic use patterns, but single-dose animal study with no individual substance control groups
When this study was published
2023 study
The bigger picture
Most research studies substances in isolation, but real-world adolescent use typically involves multiple substances. This study suggests combined use may produce cumulative or synergistic effects on brain development that persist well into adulthood.
Questions still open
- Which substance or combination drives the learning impairment most? Would lower, more typical human doses produce similar effects? Are the motivational deficits reversible with extended abstinence? Why did females show earlier impairment?
Common questions
Is combining alcohol, cannabis, and nicotine as a teenager worse than using one alone?
Why were female rats affected more?
Read the original research
Alcohol and cannabinoid binges and daily exposure to nicotine in adolescent/young adult rats induce sex-dependent long-term appetitive instrumental learning impairment.
Frontiers in behavioral neuroscience, 17, 1129866
Citation
Abela, Norbert; Haywood, Katie; Di Giovanni, Giuseppe. (2023). Alcohol and cannabinoid binges and daily exposure to nicotine in adolescent/young adult rats induce sex-dependent long-term appetitive instrumental learning impairment.. Frontiers in behavioral neuroscience, 17, 1129866. https://doi.org/10.3389/fnbeh.2023.1129866
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