By Geraldine Ohonba
A new scientific study has raised concerns that long-term, heavy use of cannabis may be linked to structural changes in the brain, particularly in areas responsible for decision-making, planning, and motivation.
Researchers from the Fidmag Germanes Hospitalàries Research Foundation in Spain found evidence suggesting that extended cannabis use is associated with “thinning” in the frontal cortex — the part of the brain responsible for higher-level thinking and executive function.
What the study found
The study, presented at the European Congress of Psychiatry in Prague, examined adults who had used cannabis daily for at least five years. Their brain scans were compared with those of individuals who had used cannabis only a few times in their lifetime.
Researchers observed thinning in the right rostral middle frontal cortex, a region strongly linked to:
- Decision-making
- Planning
- Working memory
- Motivation and goal-directed behaviour
Lead researcher Ana Aquino-Servin explained that these cognitive functions are essential for everyday life, from solving problems to completing complex tasks.
She noted that while users may still be able to perform tasks, the brain may have to “work harder” to achieve the same results, potentially affecting productivity and mental efficiency.
Possible effects on motivation
The study also suggests a possible link between long-term cannabis use and reduced motivation.
Researchers observed that heavy users may experience:
- Difficulty initiating tasks
- Lower drive to complete complex activities
- Reduced efficiency in decision-making
However, scientists caution that more research is needed to confirm whether these changes are permanent or reversible after stopping cannabis use.
How cannabis may affect the brain
Scientists believe the effects may be connected to CB1 receptors in the brain, which interact with THC — the main psychoactive compound in cannabis. These receptors are especially concentrated in the frontal cortex, potentially making it more vulnerable to long-term exposure.
Ongoing debate
The findings come amid ongoing debates over the legal status of cannabis in several countries. While cannabis is legally prescribed in the UK for certain medical conditions, recreational use remains controversial.
Some political figures and campaigners argue for legalisation and regulation, while many scientists continue to call for caution due to limited understanding of long-term effects.
Expert perspective
Dr Julian Beezhold of the European Psychiatric Association said studies like this are important as global attitudes toward cannabis evolve, adding that public health policies should be guided by strong scientific evidence.
The bottom line
While cannabis use is often seen as low-risk by recreational users, this research suggests that long-term, heavy consumption may be associated with changes in brain structure linked to motivation and decision-making.
However, experts stress that more long-term studies are needed before drawing firm conclusions about permanence or causation.
For now, the message from researchers is cautious: understanding the brain’s response to prolonged cannabis use is still evolving — and the risks may be more complex than many assume.
