Hello and thank you for your question. White spots on the brain can come for many reasons. They represents areas that the brain has not received blood. They are commonly found in patients who have high cholesterol, high blood pressure and/or have a history of smoking (this could be marijuana or tobacco). Smoking generally makes you blood more liable to form clots. As such it raises the possibility of those tiny clots causing blockages in the brain. The white spots can also be from unknown reason. Many women who suffer from migraines are known to have small white spots in their brains. We are currently not sure what causes them, but suspect that they may be areas where the brain did not receive a blood supply. Therefore to answer your question, the white spots may represent white matter disease that occurred because of smoking (not necessarily marijuana) as well as other things in your lifestyle.