A narrow definition of the term addiction refers to habitual psychological and physiological dependence on a substance beyond one's voluntary control. Terms such as "workaholic," "sex addict," and "computer junkie" arose to describe behaviors that have features in common with alcoholism and other substance addictions. Substance addiction is a multi-pronged system in which lifestyle has a role but the biology of a person's body is a major factor. These substances, which are called psychoactive drugs, are what people become addicted to and are described as chemicals that affect mental processes and behavior by temporarily changing perception and awareness. There are many different theories about what addiction is and why it happens but none have been proven.
When a person uses psychoactive drugs they are releasing chemicals into their brain which causes a disturbance in the way the brain communicates. This usually causes powerful sensations such as hallucinations, euphoric highs, loss of feelings (such as feelings of pain), and depressed motoring abilities. The scientific impact that drugs have on the brain is quite complext and each drug effects it differently. When we take a drug our body has to extract the chemicals and run them through our blood stream to the brain. Once the chemicals enter the brain they attach themselves to synaptic receptors on neurons. By doing this, depending on what kind of drug has been taken, the chemicals either stimulate or block the signals sent from the presynaptic cell membrane to the receptor site on the postsynaptic cell membrane. The brain signals, which in this case are being blocked or stimulated by chemicals, are called neurotransmitters. There are 3 types of neurotransmitters which, when tampered with by drugs, produce the side effects desired by drug users.
The first of the neurotransmitters to cause the effects described above is Dopamine. Though it is one of the most important neurotransmitters, dopamine is not common, only .3% of neurons in the brain produce dopamine (Dubuc). Dopamine plays a large role in the body's motor system and movement. For example, the uncontrollable trembling of Parkinson's disease patients is caused by the number of dopamine producing neurons dwindling (Dubuc). On an opposing note, too many dopamine producing neurons in the brain is what causes people to suffer from schizophrenia. Dopamine also plays a central role in feelings of pleasure or our reward center, it is released when we eat food or drink water. When a stimulant is released into a dopamine producing neuron it causes a leak of dopamine and at the same time the drug also blocks the receptors of the postsynaptic. When the dopamine is released it makes the brain feel like it is receiving a reward which triggers the sought after pleasurable sensations which cause addiction (McKim 70).
Serotonin is the second of the 3 neurotransmitters which is affected by drugs and is believed to play a role in addiction. Both, serotonin and dopamine neurotransmitters can be considered excitatory or inhibitory it all depends on the receptor site of the postsynaptic neuron (McKim). Serotonin contributes to various functions the body performs, such as regulating body temperature, sleep, mood, appetite, and pain. Low serotonin levels are believed to contribute to depression and aggressive behavior. Antipsychotic and psychomotor drugs help to boost serotonin levels and are used in aiding psychotic and depressed people (Dubuc).
Gamma-Aminobutyric Acid (from now on referred to as GABA) is the third neurotransmitter that is affected by drugs which are considered addictive. While both dopamine and serotonin can be either inhibitory or excitatory, depending on the receptor, GABA is purely an inhibitory neurotransmitter no matter the receptor site or where in the brain it is located. GABA neurotransmitters work by connecting themselves directly to GABA receptor sites on large protein molecules called GABA...
Bibliography: Dubuc, Bruno. The Brain from Top to Bottom. Jan. 2002. Canadian Institute of Health Research. 12 Decmber 2005 .
Howard, D.J. (1984). Drug related deaths in a major metropolitan area: A sixteen year review. Journal of Applied Social Sciences, 8, 235-248.
McKim, William A.. Drugs and Behavior. Upper Saddle River, New Jersey: Prentice Hall, 2000.
Miller, N.S. (1999). Benzodiazepines: Behavioral and pharmacologic basis of addiction, tolerance, and dependence. In S.M. Powell (Ed.), The Hatherleigh guide to pharmacology (pp. 83-113). New York: Hatherleigh Press.
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