They also increase the heart rate and appetite. Motivation and cognition can be altered, making acquisition and retention of new information difficult. Long-term users may develop psychological dependence that can produce paranoia and psychosis. Because cannabis products are usually inhaled as unfiltered smoke, they are damaging to the lungs and pulmonary system and have more cancer-causing agents than tobacco. Depressants Depressants produce central nervous system depression.
Withdrawal can lead to restlessness, insomnia, convulsions and even death.
Hallucinogens LSD, PCP, mescaline and peyote are classified as hallucinogens. Hallucinogens interrupt the brain messages that control the intellect and keep instincts in check. Large doses can produce convulsions and coma, heart and lung failure. Chronic users complain of persistent memory problems and speech difficulties for up to a year after their use. Because the drug stops the brain's pain sensors, drug experiences may result in severe self-inflicted injuries.