It certainly does change who a person is. It damages virtually every part of the brain and directly causes anxiety disorder, mood swings, and a whole host of o

It certainly does change who a person is. It damages virtually every part of the brain and directly causes anxiety disorder, mood swings, and a whole host of other unpleasant psychiatric disorders (to say nothing of the physiological disorders); and it causes this damage at doses that most people would consider "moderate", if the doses are administered consistently over a long enough period.