How drugs work
Most of us recognise the destructive long-term effects that drugs can cause, no matter how good the short-lived feeling we experience from taking them. The same applies to alcohol. But it’s also easy to understand why we use and misuse drugs that pose risks to our health and well-being. Drugs can be intensely pleasurable, at first.
Drugs are chemicals that enter the brain and interfere with the way nerve cells normally process information. Some drugs imitate natural neurotransmitters, which effect how we feel; for example, narcotic pain relievers (e.g. morphine, heroin, codeine) mimic the effects of endorphins, the body’s natural ‘feel-good’ chemical. Other drugs are so similar to the brain’s natural chemical messengers that they trick brain receptors into activating nerve cells. Stimulants such as cocaine and speed cause the neurons to release too many neurotransmitters, causing the sensation users describe as the brain ‘racing’.
Almost all drugs over-stimulate the pleasure centre of the brain, flooding it with the neurotransmitter dopamine. This process produces euphoria, and that heightened pleasure can be so compelling that the brain wants that feeling back again and again. Unfortunately, with repeated use of a drug, the brain becomes accustomed to these dopamine surges and produces less of it naturally. The user then has to take more of the drug to feel the same pleasure — the phenomenon known as tolerance.
Tolerance is one of the hallmarks of physical addiction. At this stage the drug is not only something you want because you like it; it is now something your brain and body come to need. The flipside of tolerance is withdrawal, which is the development of uncomfortable physical symptoms if you stop using the drug. For example, if your system stops producing dopamine because you are taking a drug that has the same effect, when you stop taking the drug it will take your system a while to catch-up with the new situation, and to get back to producing normal dopamine levels. Without your body producing a natural level of dopamine itself you will feel sick and depressed.