It can also lead to psychosis, hallucinations, paranoia and even a physical collapse. Depressants and barbiturates can cause physical and psychological dependence that can lead to respiratory depression, coma, and death, especially when used in concert with alcohol. Withdrawal can lead to restlessness, insomnia, convulsions and even death. LSD, PCP, mescaline and peyote are classified as hallucinogens. Hallucinogens interrupt the brain's 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 experience may result in severe self-inflicted injuries. Persistent memory problems and speech difficulties may linger. Users of narcotics such as heroin, codeine, morphine, and opium develop dependence and increase the likelihood of an overdose that can lead to convulsions coma and death. Alcohol is chemically classified as a mind-altering drug because it contains ethanol and has the chemical power to depress the action of the central nervous system.