A new study warns that playing soccer could potentially affect one's long-term brain health.

The study looked at former professional players using questionnaires, clinical assessments and brain scans.

Researchers found no major impact on cognition but say participants did have lower gray matter in certain regions of the brain compared to people who didn't play contact sports.

These regions include those affecting memory, decision-making and emotional regulation.

The study also found that participants reported higher levels of anxiety and depression, along with problems with thinking or decision making.

The leader author says the study shows correlation but no causation.