my brother is 19years old he has habit of cigaratte smoking since three years .last year he starts behaving very abnormally he doesnot use to talk to anyone in house.he calls his cousins and only speaks to them and if we ask him anything he use to shout and say abusive language.he is very intelligent he got good grades in his o levels and after that he admitted in a new college and his grades started falling .he didnt study at home .and in A levels he didnot show good result and in A levels 2nd part he didnt attended college .my mother and father are very worried about his future .we think that he uses some drug with cigaratte smoking how would we help him?