How do drugs affect the brain?
Read lots.
https://www.google.com/search?q=how+drugs+affect+human+brain&oq=how+drugs+affect+human+brain&aqs=chrome..69i57.11197j0j7&sourceid=chrome&ie=UTF-8
https://www.google.com/search?q=how+drugs+affect+human+brain&oq=how+drugs+affect+human+brain&aqs=chrome..69i57.11197j0j7&sourceid=chrome&ie=UTF-8