A new study suggests that prolonged cannabis use could lead to structural changes in the brain, potentially affecting motivation, decision-making, and the ability to handle complex tasks.

Although cannabis is legally prescribed for certain medical conditions in the UK and is often considered low-risk by recreational users, researchers are raising concerns about its long-term effects.

Scientists from the Fidmag Germanes Hospitalàries Research Foundation in Spain found that extended cannabis use is associated with thinning of the frontal cortex — a region of the brain responsible for planning, decision-making, and other executive functions.

This thinning may indicate a reduction in brain cell volume or fewer connections between neurons, which could impair cognitive performance.

Lead researcher Ana Aquino-Servin explained that executive functions are essential for everyday life, including problem-solving, memory, and organizing tasks. According to her, regular and heavy cannabis users may still complete tasks, but their brains may need to work harder to do so.

She also noted that reduced motivation could be another important factor. Some evidence suggests that frequent cannabis users may experience lower levels of motivation, which can make it more difficult to initiate and complete tasks.

However, scientists emphasize that more research is needed to determine whether these brain changes are permanent or reversible after stopping cannabis use.

The findings were presented at the European Congress of Psychiatry in Prague. The study involved 46 adults who had used cannabis regularly for about 10 years, including daily use for at least five years. Their brain scans were compared with those of individuals who had used cannabis fewer than 10 times in their lifetime.

The results showed reduced thickness in a specific part of the frontal cortex among long-term daily users.

Researchers suggest that the high concentration of CB1 receptors in this brain region — which interact with the psychoactive components of cannabis — may explain its vulnerability to long-term exposure.

Experts say that as public attitudes and policies around cannabis continue to evolve, studies like this are important for better understanding potential health risks and informing public health decisions.