The user goes from taking drugs to feel good, to taking them to keep from feeling bad. Over time, drug use itself heightens the bad feelings and can leave the user suicidal. 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.