I have dealt with schizophrenia so i know alot about it, but because you don't have any multiple choice answers, here is an article online explaining the symptoms of Schizophrenia.
<span>Delusions Hallucinations Disorganized thinking <span>Agitation </span></span><span><span>Affective flattening – The person’s range of emotional expression is clearly diminished; poor eye contract; reduced body language </span><span>Alogia – A poverty of speech, such as brief, empty replies </span><span>Avolition – Inability to initiate and persist in goal-directed activities (such as school or work)</span></span>
For one teens get addicted mostly through peer-pressure and two the brain becomes confused with whats wrong and whats right once you start and can't quit.