The activation of this network is characterized by withdrawal symptoms and signs, negative affect, and drug-seeking.37 Similarly, craving involves an intense feeling state associated with stimuli predictive of, or reminding the subject of, drugs. Nevertheless, the definition of craving is much less clear and is mostly described as an emotional-motivational Inhibitors,research,lifescience,medical state.38 Thus, despite this wide use, there is little consensus on what craving means, the best way to measure it, or what mechanism accounts for the urge to use a drug.

Some have proposed that there is no single model or theory of craving; this could account for the wide variation in experimental findings of craving-related phenomena.39 Other investigators have identified several craving-related dimensions, which include specificity, Inhibitors,research,lifescience,medical strength, positive outcomes, behavioral intention, thoughts, physical symptoms, affect, and cues.40 Taken together, cravings and urges are important but complex components of the incentive motivational aspect of reward processing, and are Inhibitors,research,lifescience,medical often targets of clinical interventions

for individuals with substance use and dependence. Several cognitive models have been put forth to explain the concept of craving. These include cognitive labeling, outcome expectancy, dual-affect, and cognitive processing conceptualizations.41 Another way to conceptualize these states is to view them as metacognitions, ie, statements Inhibitors,research,lifescience,medical about other cognitions. Therefore, an individual who craves is experiencing a cognitive event, eg, a thought or feeling that is aversive or unpleasant,42 which in turn creates an increased state of awareness about this event. The degree of self-reported

urge for drugs has important implications for abstinence. Relapse to drug use has been closely linked to exposure to conditioned stimuli that frequently induce craving, and a wide variety of such stimuli, many of which were unique to individuals, have been reported.43 Specifically, those individuals Inhibitors,research,lifescience,medical who report losing urges had Selleck PARP inhibitor significant Sodium butyrate higher abstinence rates than those reporting still having the urge to use.44 Others found a significant relationship between craving and total proportion of cocaine-positive urines.45 Similarly, craving has emerged as a predictive factor for continued use in methamphetamine-dependent individuals.46 However, some investigators have called into question that subjective cravings are invariably associated with drug use.41 Moreover, there is even some evidence that cravings may actually protect some drinkers against further drinking.47 This has led some to question the assumption that craving is the underlying basis of addiction and represents the most appropriate target for treatment.