A Northwestern University study found that marijuana users have abnormal brain structure and poor memory retention. With prolonged chronic marijuana abuse, it may lead to brain changes resembling schizophrenia. The study also stated the younger the adolescent the worse the effects in the effects become later on (Hawkins).
In a report by the American Medical Association said: "Heavy cannabis use in adolescence causes persistent impairments in neurocognitive performance and IQ, and use is associated with increased rates of anxiety, mood and psychotic thought