Why Some Rats Get Hooked on Cocaine While Others Don't—And What It Tells Us About Addiction
- Olivier George
- 2 days ago
- 2 min read
We've all heard that addiction affects people differently. But why do some individuals spiral into severe addiction while others can take or leave drugs? We investigated this question using an innovative approach with genetically diverse rats, and what we found challenges some common assumptions about addiction.
The Research Question
We wanted to understand whether individual differences in addiction-like behaviors predict how much a rat will choose drugs over other rewarding alternatives. It's a crucial question because in real life, drug use involves constant choices: Do I use, or do I spend time with family? Do I get high, or do I eat a good meal?
What We Did
We worked with Heterogeneous Stock rats, a special strain that mimics human genetic diversity much better than typical lab rats. We gave these rats extended access to cocaine (up to 6 hours daily) and measured three key addiction-like behaviors: whether they escalated their drug use over time, how motivated they were to get cocaine, and whether they'd keep using despite negative consequences (electric shocks).
Based on these measures, we classified rats as having either "high" or "low" addiction scores. Then came the critical test: given a choice between cocaine and tasty food pellets, which would they pick?
The Surprising Findings
Here's where it gets interesting. When rats were sober (even after weeks of heavy cocaine use), almost all of them—regardless of their addiction score—strongly preferred food over cocaine. Even when we made the food less appealing by delaying its delivery or reducing the portion size, rats still chose food.
But the picture changed dramatically when we allowed rats to use cocaine immediately before making their choice—essentially testing them while intoxicated. Under these conditions, rats with high addiction scores showed significantly increased preference for cocaine, especially after longer drug sessions. The more severe their addiction-like behaviors, the more likely they were to choose cocaine when high.
Why This Matters
Our research reveals something important: addiction severity may predict drug choices primarily during intoxication, not during abstinence. This could help explain why people with severe addiction often make their worst decisions while under the influence—it's not just impaired judgment, but a fundamental shift in how they value drugs versus other rewards.
For treatment, this suggests that interventions might be most crucial during moments of intoxication, when the pull of the drug becomes overwhelming even for those who, when sober, know what choice they should make.
For more information about the study see the article below.
Article: Sedighim S, Carrette LL, Venniro M, Shaham Y, de Guglielmo G, George O. Individual differences in addiction-like behaviors and choice between cocaine versus food in Heterogeneous Stock rats. Psychopharmacology (Berl). 2021 Dec;238(12):3423-3433. doi: 10.1007/s00213-021-05961-1. Epub 2021 Aug 20. PMID: 34415376; PMCID: PMC8889911.
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