A comprehensive review found that initial cannabis exposure may enhance hippocampal function (strengthening drug-context associations), while withdrawal impairs hippocampal learning, potentially driving relapse as users seek to restore normal function.
Read this if you want to understand the brain mechanisms behind why cannabis habits are hard to break.
Cannabis withdrawal impairs hippocampal learning, potentially driving relapse
What the researchers found
This review examined how drugs of abuse, including cannabis, interact with the hippocampus, a brain region critical for learning and memory, to contribute to addiction.
The relationship between cannabis and hippocampal function follows a two-phase pattern. During initial use, cannabis may enhance certain aspects of hippocampal function, potentially strengthening the formation of drug-context associations. These associations are the memories that connect the rewarding experience of drug use with the places, people, and situations where it occurred.
During withdrawal, the pattern reverses. Cannabis withdrawal leads to hippocampus-dependent learning and memory deficits. According to the self-medication hypothesis, the discomfort of these cognitive deficits may drive relapse as users attempt to restore normal cognitive function by resuming use.
This dual pattern creates a cycle: enhanced learning during use builds stronger drug-context memories, while impaired learning during withdrawal provides motivation to return to use.
Why it matters
Understanding how the hippocampus contributes to addiction provides targets for intervention. If drug-context associations drive use and cognitive deficits drive relapse, treatments that weaken these associations or support cognition during withdrawal could help people quit.
The numbers in context
Six drug classes reviewed: cocaine, amphetamine, nicotine, alcohol, opiates, and cannabis. Cannabis withdrawal uniquely impairs hippocampal learning. Initial exposure may enhance hippocampal function for drug-context association formation.
How the study worked
Comprehensive narrative review of preclinical and clinical evidence on the effects of cocaine, amphetamine, nicotine, alcohol, opiates, and cannabis on hippocampal plasticity and hippocampus-dependent learning and memory.
What this study cannot tell us
Much of the evidence comes from animal models. The review covers a broad topic area with necessarily limited depth for each substance. Human hippocampal function during cannabis withdrawal is less well characterized than animal models suggest.
How to read the evidence
Comprehensive review synthesizing evidence across multiple drug classes and research methodologies, primarily from preclinical studies.
When this study was published
Published in 2016. Understanding of addiction neuroscience and the role of learning and memory continues to advance.
The bigger picture
This review places cannabis within a broader framework of how different drugs exploit the brain's learning systems. The hippocampus is not just a passive victim of drug effects but an active contributor to the learning processes that establish and maintain addiction.
Questions still open
- Could cognitive enhancement during cannabis withdrawal reduce relapse rates? Would therapies that weaken drug-context associations (like cue exposure therapy) be effective for cannabis use disorder? How do hippocampal changes interact with other brain systems in addiction?
Common questions
How does cannabis affect learning and memory in addiction?
Why do people relapse after quitting cannabis?
Read the original research
Effects of drugs of abuse on hippocampal plasticity and hippocampus-dependent learning and memory: contributions to development and maintenance of addiction.
Learning & memory (Cold Spring Harbor, N.Y.), 23(10), 515-33
Citation
Kutlu, Munir Gunes; Gould, Thomas J. (2016). Effects of drugs of abuse on hippocampal plasticity and hippocampus-dependent learning and memory: contributions to development and maintenance of addiction.. Learning & memory (Cold Spring Harbor, N.Y.), 23(10), 515-33. https://doi.org/10.1101/lm.042192.116
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