Body building supplement could be bad for the brain. L-norvaline is an ingredient widely used in body building supplements and is promoted as a compound that can boost workouts and aid recovery. Similar compounds have been linked to neurodegenerative diseases, and a study on human cells suggests L-norvaline may also cause damage to brain cells. Source 4d.
This will sound bad but it may explain why some of those bodybuilders take things a little over the top sometimes… they may be taking things that aren't setting them right in the head. The real muscle builders also take steroids which affects your hormones and causes and imbalance.