FENS FORUM 2026 — Researchers presented findings on July 6, 2026, at the Federation of European Neuroscience Societies (FENS) Forum 2026 showing that a single exposure to cocaine in mice creates changes in brain cells that persist for at least two weeks.

The research indicated that mouse brain cells exposed to cocaine produced more neuropeptides linked to addiction in humans compared to unexposed cells. Additionally, genes that help brain cells function normally became less active in mouse brain cells exposed to cocaine.

Ana Pombo, a Bloomberg Distinguished Professor at Johns Hopkins University and a Guest Group Leader at the Max Delbrück Centre for Molecular Medicine, stated, "We know that cocaine hijacks the reward machinery of the brain. Most people do not become addicted after using cocaine once, but many do after a second use or repeated exposures. However, we don't know enough about what is happening to brain cells exposed to cocaine and whether these effects are long-lasting. We have been using mice to see where the brain stores the memory of taking cocaine for the first time and to understand why addiction occurs after repeated use, even when cocaine use is months or years apart."

Researchers used a technique called genome architecture mapping to study the effects of cocaine on mouse brains. They discovered that the three-dimensional structure of the genome was altered in dopaminergic neurons in the ventral tegmental region of the midbrain in mice exposed to cocaine compared to those not exposed. These genomic changes were visible 24 hours after cocaine exposure and persisted two weeks afterward.

A single cocaine exposure also prompted the development of approximately 1,700 new chromatin domain insulation areas in mice and resulted in the loss of about 1,100 such areas. Pombo stated, "Our results suggest that a single exposure to cocaine 'rewires' the genome of these important brain cells. The fact that we found such big changes that persist for two weeks is unexpected and it suggests that the drug is leaving a longer-term 'scar' in the genome of the brain cells. These persistent changes may be setting the stage for a stronger response after a second dose of cocaine, which could help explain why the brain becomes susceptible to cocaine addiction. We still need to investigate how long these changes last for. Are they permanent, or can the brain cells recover over time? We also need to investigate how these changes translate to the risk of addiction."

Christina Dalla, chair of the FENS Forum communication committee, who was not involved in the research, stated, "Cocaine use is a serious and growing problem around the world. We need to understand the effects of this drug and how people become addicted, but it's almost impossible to study these mechanisms in detail in the human brain, so instead we look at mice. In this study, scientists have identified profound and lasting changes in mouse brain cells after just one exposure to cocaine. This shows that cocaine can alter the structure of the genome in these cells and this alteration may persist over time. These findings challenge the idea that occasional recreational use of cocaine may be harmless as they suggest that one use could change our brains and raise the risk of addiction in the future. Researching these changes in greater detail could help us understand why some people are more likely than others to become addicted. This could also help us to find new ways to treat addiction." Dalla is from the National and Kapodistrian University of Athens.

Why It Matters

This research identifies lasting genomic changes in mouse brain cells following a single cocaine exposure. The UN Office on Drugs and Crime estimates there are 25 million cocaine users worldwide.