NEUROCHEMISTRY OF ALCOHOLISM.   Term Paper ID:22072 Click to get this paper

Essay Subject: Dependence, disease concept, nature of addiction, effects, withdrawal, other drugs.... More...

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Paper Abstract: Dependence, disease concept, nature of addiction, effects, withdrawal, other drugs. Paper Introduction: Alcoholism: The Neurochemistry of Addiction Many people are affected by alcoholism. Physical dependence on alcohol is marked by chronic compulsive abuse. Moreover, for the severely dependent, alcoholic withdrawal can be life-threatening. Clearly, alcohol exerts a considerable effect upon the brain. Researchers have postulated that certain of these alterations may actually form the basis for alcohol addiction. Furthermore, such neurophysiologic phenomena may additionally be responsible for other addictive behaviors. Ethanol is a psychoactive drug. Blood alcohol concentrations of approximately 1.0 gram/liter will intoxicate non-alcoholic persons; concentrations of 4.0 grams/liter typically induce lethal respiratory depression (Harper & Kril, 1990, pp. 207-213). The chronic consumption of ethanol leads to Text of the Paper: The entire text of the paper is shown below. However, the text is somewhat scrambled. We want to give you as much information as we possibly can about our papers and essays, but we cannot give them away for free. In the text below you will find that while disordered, many of the phrases are essentially intact. From this text you will be able to get a solid sense of the writing style, the concepts addressed, and the sources used in the research paper. For example, research has shown that--compared to age-matched and sex-matched controls--the corpus callosum ofalcoholics is significantly reduced in thickness. Sellers, a professor of pharmacology atthe University of Toronto, "It would be a great oversimplification anddisservice to the elegance of the brain to postulate one system" (Holloway,1991, pp. Unfortunately, the exact effects of alcohol onthe brain remain largely unknown. Tiihonen, Kuikka, Hakola, et al. In his book, The Effect of ArdentSpirits upon the Human Body and Mind, Rush described alcoholism as amedical illness. Moreover, there have been no neuropathological findingsdescribed in association with acute alcohol intoxication. 121-127). 239-246). Advances in Alcohol and Substance Abuse, 9, 47-66.Miller, N. Among these, perhaps theprimary neurotransmitters involved include the opioid peptides, serotonin,norepinephrine, dopamine, and gamma amino-butyric acid (GABA) (Koob &Weiss, 1992, pp. Additionally, the (2-antagonist, yohimbine, is ableto reverse ethanol-induced LC inhibition. Althoughthe study of addictive behaviors and their treatment has advancedconsiderably during the last several decades, much remains to be learned.The prospect of a single neural system being entirely responsible formaladaptive behavior seems unlikely. Alcoholintoxication characteristically produces euphoria, anxiolytic action,tolerance, and physical dependence. S., & Gold, M. 121-127).In fact, some researchers believe that all pleasure derives from dopamine.The "dopamine theory" was first proposed by Roy A. 94-1 ). Wise, a professor ofpsychiatry at Concord University (Holloway, 1991, pp. It wasn't until 196 that Jellinek wroteThe Disease Concept of Alcoholism. Furthermore, opiate receptors, occur throughout thecentral nervous system. S. The chronic consumption ofethanol leads to addiction (Lewis, 199 , pp. Physical dependence onalcohol is marked by chronic compulsive abuse. 121-127). Ethanol is a psychoactive drug. Moreover, for the severelydependent, alcoholic withdrawal can be life-threatening. Nonetheless, sufficient similarities aredemonstrated by the different addictions as to imply a generalizedaddictive process. This basal neuronal firing and neurotransmitterdischarge subsequently affect drive-states, mood, and instinctualbehaviors. Second, family studies support a genetic basisfor the behaviors. Drugs with abusepotential are initially used for their positive effects. To complicate matters, the various characteristics of alcoholintoxication appear to originate in a number of different neurologicsystems (Lewis, 199 , pp. Alcohol and Alcoholism, 25, 239- 249.Lewis, M. 47-63). 1 5-112). 2 1-224). In contrast, George F. 1656-1657). (199 ). (199 ). In addition to the locus ceruleus, the ventral tegmentum, and thenucleus accumbens, other brain areas associated with addiction include thedorsal raphe nuclei and the periaquaductal grey. Alteration in the function of cerebral neurotransmitter receptors during the establishment of alcohol dependence: Neurochemical aspects. Anoradrenergic response associated with LC hyperexcitability is actuallyresponsible for the signs and symptoms of withdrawal (Miller & Gold, 1993,pp. J. Third, among users, multiple addictions can be reliablyidentified as independent disorders. Unfortunately though, prohibition emphasized the moraland legal aspects of alcoholism. Prolonged abstinence can reverse alcohol-induced brain shrinkage. Koob of the Scripps Institute in La Jolla,California, believes that--in addition to dopamine--other neurotransmittersare involved. Perhaps the most obvious abnormality found inalcoholic brains consists of shrinkage. Common neuralpathways for addictive behaviors occur in the limbic system. Such effects could, forexample, influence both receptor binding and intracellular signaltransduction. In addition, increased membrane fluidity might also impact membrane-bound enzymes and neurotransmitter receptors. 2 7-213). 94-1 ).Accordingly, "strongly habit-forming drugs ultimately cause the release ofdopamine in a part of the mesolimbic system called the nucleus accumbens"(Holloway, 1991, pp. For the alcoholic, drinking becomes at least asimportant as other physiologic needs (e.g., eating and sex) (Miller & Gold,1993, pp. The withdrawal effects of several addictive drugs have been associatedwith the brain's locus ceruleus (LC). Psychiatric Clinics of North America, 16, 1 5-117.----------------------- 1 Moreover, there is significant evidence that (2-adrenoreceptorsmay be involved in the pathogenesis of alcohol dependence. Alcohol and Alcoholism, 25, 2 7-216.Holloway, M. JAMA, 273, 1656- 1657.Harper, C. J. (cited inFranklin, 1995, pp. 2 1-224). Various investigations have shown that ethanol can suppress LCactivity. 223-227). For instance,the (2-agonist, clonidine, can be used to ameliorate some of the symptomsof alcohol withdrawal. 47-63). The LC is normally activated bypain, blood loss, and cardiovascular collapse. (1993, April-June). F., & Weiss, F. Alcohol: Mechanisms of addiction and reinforcement. Investigations using polyurethanefoam casts have found that, at autopsy, alcoholics have a mean PICS of 11.3percent. E. 2 7-213). Fourth, and most importantly, recentresearch involving human and animal models has provided evidence ofneurochemical, neurophysiologic, neuropharmacologic, andpsychopharmacologic mechanisms common to both alcohol and drug addictions(Miller & Gold, 1993, pp. Perhaps the most important development in the study of alcoholismconsists of the "disease concept" (Baciewicz, 1993, pp. This brain shrinkage was firstdocumented using pneumoencephalography; more recent studies, however, haveemployed computed tomography (CT) techniques. A neurochemical basis for alcohol and other drug addiction. Clinical Obstetrics and Gynecology, 36, 223-231.Franklin, J. Scientific American, 264, 94-1 3.Koob, G. ReferencesBaciewicz, G. gram/liter will intoxicate non-alcoholic persons;concentrations of 4. Despite such progress though, the exact nature of ethanol-induced neuronal alteration remains poorly understood at present. Hence, (2-receptors might beinvolved in the development of both ethanol tolerance andwithdrawal (Miller & Gold, 1993, pp. In addition, pharmacological studies have implicated several brainneurotransmitter systems in alcohol addiction. Furthermore, such neurophysiologic phenomena may additionallybe responsible for other addictive behaviors. A specific alcohol "receptor" has yet tobe discovered. Alcoholism: The Neurochemistry of Addiction Many people are affected by alcoholism. Neuropathology of alcoholism. 1 5-112). 1 5-112). The disease isoften progressive and fatal. CTscan data has indicated that alcoholics' brains exhibit decreased density.Hence, reversible white matter shrinkage could result from some change inone of the central nervous system's major structural elements. While the nucleus accumbens could be a major pleasurecenter, it might also merely represent a first step in the pleasurepathways. Abundant research seems to support a uniform theory for theneurochemical basis of alcohol and other drug addictions. S. According to Edward A. Investigative analyses have shown that alcoholism causes anincrease in the relative proportion of cholesterol in some cell membranes.Chin and Goldstein (cited in Harper & Kril, 199 , pp. Rather, drug and alcohol addictionprobably results from multiple contributory effects involving a number ofdifferent systems. However, it has not yet beendetermined which of these attributes most influences the development ofaddiction. 1 5-112). 94-1 ). (1993, March). (1991). These diverse neurophysiologic mechanisms areinherently difficult to describe. Histofluorescence mapping techniques havedemonstrated a close association between this brain stimulationreinforcement region and the mesotelencephalic dopamine system. Theventral tegmental area of the limbic system contains dopamine cell bodiesprojecting fibers to the limbic cortex (Miller & Gold, 1993, pp. 2 7-213) speculatedthat this alteration may represent some type of "adaptive response tochronic ethanol exposure" (Harper & Kril, 199 , pp. 121-127). A recent study performed in the United Statesconcluded that the rate for a lifetime diagnosis of alcoholism in thegeneral population was 16 percent. A hypothesis for a common neurochemical basis for alcohol and drug disorders. Many of the attributes of alcoholism are common to other addictions.In general, addiction involves both psychological and physical dependence(Koob & Weiss, 1992, pp. Pathologic confirmation ofthese analyses can be obtained through studies of either brain weights orpericerebral space (PICS) measurements. In contrast, the positive effects of alcohol abuse derive from sometype of reinforcement reward system. The consequentincreased membrane fluidity may affect membrane permeability. Journal of Psychoactive Drugs, 25, 121-128.Miller, N. Thevarious lipid components present include cholesterol, phospholipids, andgalactolipids. Intoxication,however, is thought to result from the incorporation of ethanol intoneuronal membranes (Harper & Kril, 199 , pp. G., & Kril, J. Various observations imply a common neurochemical basis for addictionto alcohol and certain other drugs. (1995, June 7). Neuropharmacology of cocaine and ethanol dependence. 2 7-213). The uncertainty surrounding alcoholic neurochemistry has causedwidespread disagreement among researchers in the field. Yet another supporter of this hypothesis,Gaetano Di Chiara of the University of Cagliari in Italy, claims thatopiates, nicotine, amphetamines, cocaine, and alcohol, all elevate thenucleus accumbens' dopamine levels. The American Psychiatric Association'sDiagnostic and Statistical Manual of Mental Disorders (DSM-IV) dividespsychoactive substance use disorders into categories of abuse anddependence. (1993, June). Addiction medicine. By identifying five "species" ofalcoholics, this work contributed to the concept of alcoholism as aprogressive pathologic condition (Baciewicz, 1993, pp. This compares to a control value of 8.3 percent (Harper & Kril,199 , pp. Recent Developments in Alcoholism, 1 , 2 1-233.Kuriyama, K., & Ohkuma, S. Lipids, forexample, account for 5 to 6 percent of the human brain's dry weight. For females, the rate was measured at 6percent; whereas, among males it was found to be as high as 29 percent(Miller & Gold, 1993, pp. 223-227). The process of addiction. Much of thisdebate has focused on the mechanism of addiction. Blood alcohol concentrations ofapproximately 1. Overall, these differentsites contain cell bodies and receptors for many differentneurotransmitters. Rx for addiction. 223-227). One particular region of the brain which may be responsible for thepositive reinforcement associated with addictive behaviors consists of themedial forebrain bundle (MFB). Although the cerebralcortex is less affected by alcohol, cortical neuronal counts havedemonstrated a loss of neurons from the superior frontal cortex.Furthermore, this apparent regional loss correlates with CT scan andneuropsychological study results. Moreover, they also provide the mechanism by which drug use becomesan acquired drive state. Alcohol anddrugs that activate "brain reinforcement circuits either enhance brainstimulation or lower brain thresholds for reinforcement through basalneuronal firing and/or basal neurotransmitter discharge" (Miller & Gold,1993, pp. Moreover, alcohol-induced brain shrinkage seems toprimarily affect the white matter. Researchers have postulatedthat certain of these alterations may actually form the basis for alcoholaddiction. That alcohol severely affects brain structureand function is certain. It is characterized by impaired control overdrinking, preoccupation with the drug alcohol, use of alcohol despiteadverse consequences, and distortions in thinking, most notably denial.Each of these symptoms may be continuous or periodic" (Baciewicz, 1993, pp.223-227). (199 ). In opioid-dependentanimals, however, the locus can be activated by abstinence. 1656-1657) recently employed high-resolution singlephoton emission CT to demonstrate right prefrontal cortex and endogenousopioid system activation during ethanol intoxication (Franklin, 1995, pp.1656-1657). Clearly, alcoholexerts a considerable effect upon the brain. (1992). For one, alcohol and drug addictionsoften occur in combination. More recently, the National Council of Alcohol and Drug Abuse and theAmerican Society of Addiction Medicine has defined alcoholism as follows:"A primary chronic disease with genetic, psychosocial, and environmentalfactors influencing its development and manifestations. J. S., & Gold, M. grams/liter typically induce lethal respiratorydepression (Harper & Kril, 199 , pp. 2 7-213). The human central nervous system is obviously very complex. It is widely believed that neurochemical mechanisms are responsiblefor the "loss of control" typically experienced by the addict (Miller &Gold, 1993, pp. One phenomenon associated with drug addiction is withdrawal syndrome. Recent studies have "clearly demonstrated that the functionof neurotransmitter-gated and receptor-coupled ion channel as well as thatof neurotransmitter receptor coupled with intracellular mediator systemsinvariably deteriorate during alcohol dependence" (Kuriyama & Ohkuma, 199 ,pp. These centers--which are thought tobe anatomically distinct from those associated with tolerance andwithdrawal (i.e., the LC)--produce an "inherently pleasurable, positivelyreinforcing, subjective brain reward or 'high'" (Baciewicz, 1993, pp. Alcohol use and abuseaffect many people. Thisconcept was first cultivated during the 18th century by the founder ofAmerican psychiatry, Benjamin Rush. Accordingly, DSM-IV describes substance abuse as "amaladaptive pattern of use, leading to clinically significant impairment ordistress, as manifested by three (or more) of the following symptomsoccurring at any time in the same 12-month period: (1) tolerance; (2)withdrawal; (3) substance taken for longer periods or in larger amountsthan intended; (4) persistent or unsuccessful efforts to cut down on use;(5) a great deal of time spent in activities necessary to obtain thesubstance or recover from its effects; (6) important social, occupational,or recreational activities given up or reduce because of use; and (7)continued use despite knowledge of having a persistent or recurrentphysical or psychological problem likely to be caused or exacerbated by thesubstance" (Franklin, 1995, pp. If this paper is not what you are looking for, you can search again: Search for: or Click here to request an essay written just for you.