Alcohol lowers our inhibitions, slows neural processing, disrupts memory formation, and reduces self-awareness. Alcohol increases harmful tendencies and helpful tendencies, but either way, it increases what we are normally feeling which can turn out to be harmful. In addition, in low doses, alcohol slows the sympathetic nervous system activity. In large doses, alcohol causes slowed reactions, slurred speech, and a deterioration of skilled performance. Alcohol is a sedative. Also, alcohol disrupts the processing of recent experiences into long-term memories. If consumed in large amounts, the effects on the brain and cognition can be long-term. Alcohol can impair the growth of synaptic connections and contribute to nerve cell death. It can shrink the brain, which can lead to lung and liver damage. Next, alcohol reduces self-awareness and lessens impulse control. Drinking also is linked with an increase in risky sex, which often results in unplanned pregnancies, rape, and STDS.
Barbiturate drugs, or tranquilizers, mimic the effect of alcohol. They depress nervous system activity, impair memory and judgement, induce sleep, and reduce anxiety.
Opium, and its derivatives, morphine and heroin, also depress neural functioning. Pupils constrict, breathing slows, and lethargy sets in. They reduce pain and anxiety. With the continued use of opiates, the brain stops producing its own opiates (the endorphins), and when the artificial opiate is withdrawn, the brain lacks the normal level of these painkilling neurotransmitters, which could ultimately lead to death.