Well I have personally used/abused steroids for about 5 years of my life (not as a teenager though) and, yes, they did make me bigger,stronger, and more aggressive. Especially at high doses. It is sort of like being manic without the not eating part ( they make you HUNGRY). However, you still have control of your mental faculties, for the most part. Did I ever do things that I may not have done otherwise? probably. Am I still a raging menace to society? ( I suppose that depends who you ask) Not in my opinion. They do have effects on the brain as well as muscles. No doubt about that.
Lets not forget that each and every one of us has nartural 'steroids' of various varieties produced in our bodies daily. If someone was going to pay me $10 million a year to be a big mean SOB then I'm in.