Brain damage seems one to not forget, but there are others. Like freedom, without being related to a single aspect when you enjoy any activity. When a user takes a drug, Nature wants consequences during a period of time; longer.
Clumsiness, reduction of reflexes could be the reason to have an accident, as with other perception-based effect. Memory fails more with drugs, obviously, like multiple intensive intellectual abilities compared with people that don't consume. It's no magic when it comes to specialized tests.
Health damage and risks, specially with those drugs that come after a chemical process, done in the dark, who knows with what security measures and elements. The problem of differences in composition, purity or variety usually leads to even deaths advancing from different degrees of problems.
No drug could be recommended because in an overall view it must be worse than to not consume. Why? Because otherwise any external judge would appreciate more pros than contras, and this is not the case. Drugs will always have more contras so it's better to stay aside.
Young people and those that advance age from those experiences tend to disagree, but anyway it's a numeric reality that produces measurable damage as well.