Drugs can remain in the body long after use has stopped. The extent to which a drug is retained in the body depends on the drug's chemical composition. Such accumulations of drugs and their slow release over time may have effects on the mind and body weeks or even months after drug use has stopped. Drugs can interfere with memory, sensation, and perception. They distort experiences and cause a loss of self-control that can lead users to harm themselves and others.
Drugs interfere with the brain's ability to take in, sort, and synthesize information.
As a result, sensory information runs together, providing new sensations while blocking normal ability to understand the information received. Research shows that drugs erode self discipline and motivation necessary for learning and cause a decline in academic and work performance as well. The marijuana produced today is from 5 to 20 times stronger than that available as recently as 10 years ago. Research has shown that severe psychological damage, including paranoia and psychosis, can occur when marijuana contains 2 percent THC, its major psychoactive ingredient. Since the early 1980's, most marijuana has contained from 4 to 6 percent THC - two or three times the amount capable of causing serious damage.