Persisting consequences of drug intake: towards a memory of addiction.
Long-term intake of a psychoactive drug alters brain signal transduction, emotional and motivational factors and behavioral parameters. Some effects that outlast long periods of abstinence are due to the long-term presence of the drug in the organism (tolerance, physical dependence). Withdrawal symptoms, as a consequence of physical dependence, can be protracted, i.e. they persist after long periods of drug deprivation (e.g. a desensitization of the production of cAMP). Further persisting effects include experience-based learning. At least three distinct processes can be differentiated: a memory of drug effects (reflected by a sensitization to drug effects etc.), a memory of drug use (reflected by controlled drug consumption), and a memory of addiction (reflected by a persisting loss of control over drug intake and correlating changes in striatal dopaminergic neurotransmission). The latter probably consists of two components: a general memory of loss of control and a specific memory of the addictive drug (general principles for the development of addiction, specific of the urge for the addictive drug).
Heyne
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Abteilung für Klinische Neurobiologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Federal Republic of Germany. aheyne@zedat.fu-berlin.de
May
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Goll
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Wolffgramm
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D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D008568:Memory / Q000187:drug effects* / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D019966:Substance-Related Disorders / Q000503:physiopathology*