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.
Alcohol consumption causes a number of marked changes in behavior.
Even low doses significantly impair the judgement and coordination required to drive a car safely, increasing likelihood that the driver will be involved in an accident. Low to moderate doses of alcohol also increases the incidence of a variety of aggressive acts, including spouse and child abuse. Moderate to high doses of alcohol cause marked impairment in higher mental functions, severely altering a person's ability to learn and remember information. Very high doses cause respiratory depression and death. If combined with other depressants of the central nervous system, much lower doses of alcohol will produce the effects just described.