A psychoactive drug is any substance that will influence the brain and behavior of humans. How these affect individuals depends on a person's tolerance to the drug. Often times the more people use a drug, the higher their tolerance for it, meaning they will need more of the drug to produce the same effect. This can be very dangerous when it comes to illegal drugs. While many people believe the top used drugs are illegal (marijuana, cocaine, and meth for example), the most commonly used drugs are actually alcohol, nicotine, and caffeine. Since these are all addictive substances, people often experience substance dependence, causing withdrawal when they cease to use them. For example, many people become addicted to alcohol, a depressant. Since it is a depressant, alcohol inhibits normal neural functioning. The neurotransmitter GABA is affected by alcohol, which is what causes the lowering of anxiety. It also inhibits the cerebral cortex slowing the way we think and feel about things. Another major thing alcohol inhibits is the brain stem, which causes the dizziness, slurred speech, memory, and judgement. When too much alcohol is consumed during pregnancy, the fetus is even affected, causing fetal alcohol sydrome (FAS) which leads to many birth defects. Because alcohol affects so much of the brain, it can often lead to very poor decisions, such as aggression towards other people, driving when you can barely stand, etc.
Caffeine, a stimulate, causes the brain to speed up its normal activity. It does this by blocking the neurotransmitters (adenosine) that cause the nervous system to slow down. This is what helps people to stay awake and feel alert when they consume caffeine. Side effects of caffeine can cause insomnia, stomach problems, anxiety/nervousness, and irritability. Caffeine is also an addictive drug causing withdrawal symptoms when a person stops using it.
Another very addictive stimulate is nicotine. Nicotine leads to more than 440,000 deaths a year because it is linked to lung cancer, throat cancer, emphysema, and heart disease. If used during pregnancy it reduces the amount of oxygen the fetus gets, causing it to be irritable, have respiratory problems, and a lower birth weight when born. Nicotine is addictive because it affects the neurotransmitters acetylcholine and glutamate, and elevates dopamine levels. This improves attention and memory, and leads to feelings of pleasure. If too much is consumed, however, it can cause vomiting, diarrhea, sweating, and dizziness. Because nicotine is so addictive, it's withdrawals last from 2-6 weeks, just like alcohol, cocaine, and morphine. Because it's withdrawals last so long, many people find it very difficult to quit. As low as 2 out of 10 people that try, actually succeed.
(Information from pages 153-168 in "What is Psychology" by Ellen Pastorino and Susann Doyle-Portillo)
Re:
This is a very nice explanation of psychoactive drugs and their effects. However, you did not use the class videos or any outside resources to add to this. Doing this "extra" will help you get higher grade in future posts.