Behavioral disorder at a times aggressiv

My brother was very good at studies bt from last 4 years since he was in 8th standard he is having exam pressure or phobia. now he became very aggressive at times and then very depressive as well. he has became so possessive about everything related to him. he keep on doubting everyone n everything. he cant even eat anything doubting as sm1 has added smthing in it. he dont hv a big peer group..as he used to live alone so he has spend most of his times watching movies or playing games either in laptop or in tablet. he has became very talkative that he consistently keep on talking.. he couldn't sleep well. n keep on thinking all the time. my father is also a hyper mania patient. bt for few months it happens to him.. is it possible that my brother is having problem like my father.. is it a genetic issues. please help me n suggest whom should i contact as he is very young now ie 17 yrs. i dnt want him to take medicines. please help