Physiological basis
Although the term addiction is sometimes often used loosely rather than as a medical classification, there are some physiological conditions related to everyday behaviors that are also related to the more commonly recognized mechanisms associated with addiction. Pleasurable activities cause the release of endorphins, and this endorphin-rush can conceivably become 'addictive'. Evolutionary biologists have suggested this process of attentuating pleasure pathways is part of the brain's natural system for ensuring that humans develop abiding interests. Since human societies depend on enduring attachments, many theorists suggest such addictions are not necessarily a problem. Other views, such as the those summarized in Buddhist concept of tanha, suggest trivial attachments are at the root of much human suffering.
The pathways oriented to endorphins, sometimes called pleasure centers originated in small organisms such as insects, which rely on the neurological system to help them find familiar sources of food.
In general terms, endorphins stimulate activity of the neurotransmitter dopamine. Increased dopamine activity is often met by an increase in the number of receptors sensitive to dopamine. This process is called upregulation. The increased number of receptors tends to result in reduced electrical activity along post-synaptic nerve pathways, unless some behavior or substance causes a continued high level of dopaminergic stimulation. The absence of a pleasurable sensation in conditions that were formally sufficient can cause a mild feeling of let-down after neurons have been upregulated. The increased requirement for dopamine to maintain electrical activity is the basis of both physiological tolerance and withdrawal associated with addiction.
In cases of physical dependency on depressants of the central nervous system such as opiates, barbiturates, or alcohol, the absence of the substance leads to symptoms of sometimes severe physical discomfort. In these cases, a body has become so dependent on a chemical that it has stopped producing the necessary neurotransmitters required to maintain a comfortable status.
Opiates present extreme risks of physical dependency because they are chemically similar to endorphins, causing an upregulation of dopaminergic receptors without stimulation of the endorphin systems. Cocaine and amphetamines also pose risks associated with physical attenuation, cocaine for its chemical similarity with dopamine, and amphetamines by their similarity with norepinephrine which acts indirectly to stimulate dopaminergic pathways in the brain.
Casual addiction
The word addiction is also sometimes used colloquially to refer to something a person has a passion for. Such "addicts" include:
See also
External links
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