Why is Meth So Addictive?

They produce an initial pleasurable effect on the user
An unpleasant rebound effect afterwards

An amphetamine (such as crystal meth) through its stimulant effects, produces a positive feeling, but when it wears off it leaves a person with the opposite feelings. This is because of the suppression by the drug of the normal production of adrenaline. Now, a chemical imbalance has taken place and the result is irritability that physically demands more of the drug to go back to feeling normal good again. This pleasure/tension cycle leads to loss of control over amphetamines or any other addictive drug.

The brain's reward system consists of various drives and needs of the body; sex, hunger, thirst and friendship. When these drives are satisfied, or when pain is relieved, a signal is sent to certain brain cells which manufacture a chemical substance that signals reward. When these monitor cells have been stimulated, a signal is sent to the tip where a small amount of this reward chemical is released. The chemical or neurotransmitter then reaches and stimulates the reward center, causing a feeling of well-being.

Crystal Meth is able to produce these artificial feelings of pleasure. Most addictive drugs are able to produce pleasurable effects by chemically mimicking certain normal brain messenger chemicals which produce positive feelings in response to signals from the brain. A wonderful example of this is the narcotic drug morphine which mimics endorphins. When the drug comes in, it stimulates the reward center. This short circuits the survival mechanism, because the reward center cell can't tell the difference between the drug and the natural chemical messenger. Often the result is addiction and dependence to the immediate, fast, and predictable drug which caused the effect. While this is taking place, the user's brain short circuits in a way leaving their brain less able to make life's normal rewards work for them anymore. When the amphetamine molecule comes in through the blood stream, it bypasses the natural nerve cells and causes the artificial release of normal, chemical messengers for positive feelings. What happens as a result of this is a feeling of satisfaction, well-being and relief. Then, automatically the system sends a signal of positive rewards back to the memory of this activity. The first of many pleasure hooks has been implanted into the memory. The amphetamine drug lies to both the reward center and to the Monitor Cell. The cell adapts to the excess stimulating effect of amphetamine by shutting down production of the natural stimulatory chemistry, to try to keep a balance.