What is craving?
Craving can persist years into abstinence (1).
Precise definitions of craving have remained elusive (2-5). Two general categories are based on conditioning and cognitive mechanisms (6) but are not mutually exclusive.
A Neuroadaptive Model of Craving – Scientists believe that a gradual and, perhaps, permanent adaptation of brain function (i.e., neuroadaptation) to the presence of alcohol is a central feature in the development of alcohol dependence (7,8).
Conditioning Models – The “conditioning” models posit that cues elicit the same physiological and psychological response as drug consumption itself with these ‘respondent’ conditioning theories predicting that responses to drug-related cues either reflect aversive abstinence symptoms or mimic drug effects have dominated explanatory models in cue reactivity studies (9).
The definition of addiction by the American Society of Addiction Medicine (ASAM) includes the terms craving and persistent risk, and emphasizes risk of relapse after periods of abstinence triggered by exposure to substance-related cues and emotional stressors (10).
This conceptualisation points to the role of substance-related cues, e.g., environmental stimuli that are strongly associated with the effects of the administration of substances and acquire incentive salience through Pavlovian conditioning, as well as stress (an internal cue), as major determinants of relapse.
The Incentive Sensitisation (IS) Model (11), addiction is the result of neural sensitisation of reward circuits (centred in the ventral striatum (VS)) by the neurotransmitter dopamine. Positive reinforcement mechanisms lead to a non-associative learning process, referred to as sensitization, in which repeated confrontation with a substance-related cue (which acts as a reinforcer) results in the progressive amplification of a response (substance seeking).
This ‘sensitisation’ or hypersensitivity may be independent of negative withdrawal symptoms or an individual’s general negative emotional state and leads to compulsive substance-seeking and substance-taking. These mechanisms of positive reinforcement leave addicts vulnerable to relapse when confronted with substance-related cues that trigger a pathological “wanting”. In short, IS produces a bias of attentional processing towards substance-associated stimuli and a pathological wanting of alcohol or substances. Sensitisation and attentional bias have been demonstrated in various studies (12,13).
Negative reinforcement model of addiction Basic negative reinforcement models pose that addictive behaviour is the consequence of persistent negative affect (NA). This NA is associated with maladaptive changes in the brain’s stress and reward circuits, which leave addicts vulnerable to cue-associated stimuli prompting a desire to relieve their negative emotional states (14).
One prominent stress-based negative reinforcement model, the Hedonic Dysregulation (HD) Model, mainly associated with Koob and le Moal (14), In sum, the HD model posits that, in substance dependent individuals, an overactive stress axis creates a progressive allostasis in the brain reward systems which underlies transition from substance use to addiction and creates a persistent state of NA (altered and excessive stress) and emotional reaction to “cues”. These changes continue to persist even when an addicted individual experiences a state of protracted abstinence.
Persistent NA increases their incentive salience and desire to use substances in an attempt to relieve this NA.
Evidence for the involvement of both the reward and the stress system of the brain comes from imaging studies of addicted individuals during withdrawal or protracted abstinence, which have shown decreases in dopamine D2 receptor density (hypothesized to reflect hypodopaminergic function) (15) as well as alteration in brain stress systems, such as increase in CRF and glucocorticoids (16).
These models to me appear to be describing urges based on cues and the effect of cues with stress/emotional distress. This last one can impact on recovery and relapse mentioned in another blog.
The question remains however whether these neurobiological models predict relapse in abstinent alcoholics and addicts?
In other words, do recovering alcoholics act and react to cues and have the same attentional bias, i.e. are they lured siren-like to alcohol or drug cues like lemmings to a drink or a drug or are there more cognitive-affective processes at work in the craving than these models suggest!?
Does the mind play a role in transmuting these physiological urges into “craving”.
When I have seen a new comer to recovery craving they do not seem to walk around like a robot, salivating and rubbing their sweaty hands together. I have seen that when I was in active drinking and was like that innumerable times myself while under the spell of this “fleshy hunger” called having a pathological urge for a drink.
I am not downplaying this urge state, it is quite horrendous, it is like craving a glass of water after days in the desert. It feels like your very life depends on it, in other words. It can be a life or death feeling.
In recovery, this urge state becomes more complicated and various other brain regions may become involved in this “craving” and there may be a interplay between regions rather than regions simply acting in concert – we will explore this more in our next blogs on this theme of “craving”.
For now we examine how well do neurobiological accounts (i.e. accounts which focus primarily on impairments in neurotransmitter and stress systems and brain function in areas which create a cascade of ‘knock on’ impairment and dysfunction in areas of the prefrontal cortex which deals with cognitive control of behaviour with resultant dysfunction in areas which deal with reward, motivation stress and emotional response and more motoric, habitualized action) predict behaviour in abstinent, treatment seeking individuals?
Here we simply consider how well aspects of these theories, such as the ideas relating to craving (urge) via cue reactivity (an attentional bias towards alcohol and drug associated cues in the environment) and positive memory associations for previous alcohol or drug use, relate to, or are relevant to the experiential reality of everyday recovering alcoholics and addicts.
In simple terms, it is the duty of science to attempt to predict behaviour, so how well do these models, especially the positive reinforcement model, predict the behaviour of treatment seeking abstinent alcoholics and addicts.
Factors in relapse
Cues, external especially, which is a central part of positive reinforcement models, seem to be only one of various factors in relapse. They are present in a relatively small minority of studies or interact with other variables such as stress and negative affect (NA). So how well does this then validate this theory of addiction, when it is only present in a minor way in relapse and usually alongside stress and NA. Does this mean it plays a role when interacting with these variables of stress/NA. Does it play a role on it’s own?
I forward this question because the looking at an alcohol cue by an alcoholic even in recovery/abstinence invokes stress reactions such as anxiety or negative emotions such as anger, sadness. Can we say there is a non-stress influenced cue-reactivity? Is there a purely dopaminergic cue reactivity? It doesn’t appear so.
In fact moving on from noting this intrinsic stress response in cue reactivity, various studies show that the highest high-risk relapse situations are negative emotions, testing personal control, social pressure, and urge and temptations (17), that 62 –73% of relapse episodes were due to negative emotion and social pressure. Heroin addicts relapse primarily because of NE and lack of social supports. Mood state, along with social isolation and family factors, was more likely to be related to relapse incidences with a positive correlation between NE and alcohol-seeking behaviour. Thus the most commonly cited reason for relapse was negative mood states, consistent with previous studies of relapse factors (18). Also reasons for relapse did not differ in relation to the primary drug of dependence (alcohol, methamphetamine, heroin), reflecting the commonality of relapse processes across diverse types of substances.
Marlatt (19,20) , views relapse as an unfolding process in which resumption of substance use is the last event in a long sequence of maladaptive responses to internal or external stressors such as negative emotional states, interpersonal conflicts, and social pressures. In fact negative emotional states ….coping, self-efficacy and stressful life events appeared to be of greater import in determining relapse than ‘cues’.
It would appear that cue associated stimuli plays a minor role in relapse, with stress and NA appearing to be a more important determinant of relapse. So conditioning models do not appear to give a comprehensive account of relapse and this may be particularly the case in abstinent, treatment seeking alcoholics.
How does conditioning methodology adequately explain this group?
Do treatment seeking alcoholic have the same attentional bias as non treatment seeking active alcoholics?
In fact, studies seem to show a negative attentional bias in alcohol-dependent patients that may be interpreted as an avoidance of alcohol-related stimuli.
Townshend and Duka (2007) propose that treatment seeking individuals have established active avoiding strategies and are able to disengage their attention from alcohol cues (21). In fact is suggested that a positive attentional bias towards alcohol cues occurs when stimuli were presented shortly (50 ms), followed by a disengagement from alcohol cues in the 500 ms interval of cue presentation. This corresponds with a cognitive model of craving of Tiffany (22) where the 50ms may represent automatic approach before this automatic bias is interfered with by cognitive control, perhaps resulting in ‘craving’.
Does this visual approach–disengagement pattern reflect an attentional bias which is appetitive or threat based? If there is avoidance are cues similar as seen as in those with trait anxiety who have attentional bias for threat-related cues (23). A large body of evidence indicates that aversive emotional states are associated with biases in cognitive processing and, specifically, with increased attentional processing of threat-related cues. Is this also how treatment seeking addicted individuals are responding to substance-related cues? It may that stress heightens the salience of attractiveness of the cues so that abstinent individual relapse because of stress based response which makes relapse via internal and external cues a solution to their chronic stress/emotional distress?
Or it may be that relapse is based on difficulties coping with the manifestation of chronic stress, emotional distress and that relapse is a more complicated process than simply being lured, siren-like, to relapse via cues.
In most of the relapses we have encountered it has been a ongoing build up to relapse. There has been a period of emotional dysregulation whereby individuals get more and more distressed, often in inter-personal relationships, and have a “to hell with it!” relapse to relieve escalating emotional distress and the distorted thinking that goes with it. It is not due to automatic or motoric processes, it is mediated via affective-cognitive mechanisms and this is why the information processing model, with some modifications, appears to explain craving and relapse more satisfactorily.
If you want to drink, you will, if you do not, and depending on your regulation of emotions and stress, you may still relapse, even if one never intended to drink again, due to the torturous intrusive thoughts which accompany this cognitive and emotionally based “craving”, more akin to the “mental obsession ” of AA’s Big Book than purely physiological urges.
Finally it is interesting to note that (24) alcoholics in treatment had developed a negative memory association linked to alcohol as opposed to those not in treatment. This suggests that treatment changes our alcohol-related schema from a so-called positive or reward based bias to a negative, aversive bias. As we shall see in our next blog on "craving" even this negative bias can still lead to "craving" and this will demonstrate why we need to constantly let go of distress based thoughts and memories. If we react emotionally to alcohol or drug related thoughts these thoughts via our inherent emotional dysregulation can lead to a further proliferation of the very same thoughts, and it is this increasingly distressing mental obsession that can lead us to relapse. We are then without mental defence.
1. Anton, R. F. (1999). What is craving. Alcohol Research and Health, 23(3), 165-173.
2. LUDWIG, A.M., AND STARK, L.H. Alcohol craving: Subjective and situational aspects. Quarterly Journal of Studies on Alcohol 35:899–905, 1974.
3. KOZLOWSKI, L.T., AND WILKINSON, D.A. Use and misuse of the concept of craving by alcohol, tobacco, and drug researchers. British Journal of Medicine 82:31–45, 1987.
4. KOZLOWSKI, L.T.; MANN, R.E.; WILKINSON, D.A.; AND POULOS, C.X. “Cravings” are ambiguous: Ask about urges and desires. Addictive Behaviors 14:443–445, 1989
5. SITHARTHAN, T.; MCGRATH, D.; SITHARTHAN, G.; AND SAUNDERS, J.B. Meaning of craving in research on addiction. Psychological Reports 71:823–826, 1992.
6. SINGLETON, E.G., AND GORELICK, D.A. Mechanisms of alcohol craving and their clinical implications. In: Galanter, M., ed. Recent Developments in Alcoholism: Volume 14. The Consequences of Alcoholism. New
York: Plenum Press, 1998. pp. 177–195.
7. Robinson, T.E., & Berridge, K.C. (1993). The neural basis of drug craving: An incentive-sensitization theory of addiction. Brain Research, 18, 247-291
8. Koob GF, Le Moal M. Drug abuse: hedonic homeostatic dysregulation. Science. 1997;278:52–58
9. Ingjaldsson, J. T., Laberg, J. C., & Thayer, J. F. (2003). Reduced heart rate variability in chronic alcohol abuse: relationship with negative mood, chronic thought suppression, and compulsive drinking. Biological Psychiatry, 54(12), 1427-1436.
10. Morse RM, Flavin DK (1992). “The definition of alcoholism. The Joint Committee of the National Council on Alcoholism and Drug Dependence and the American Society of Addiction Medicine to Study the Definition and Criteria for the Diagnosis of Alcoholism“. JAMA 268 (8): 1012–4
11. Robinson, T. E., & Berridge, K. C. (2008). The incentive sensitization theory of addiction: some current issues. Philosophical Transactions of the Royal Society B: Biological Sciences, 363(1507), 3137-3146
12. Leyton M. Conditioned and sensitized responses to stimulant drugs in humans. Prog. Neuropsychopharmacol. Biol. Psychiatry. 2007;31:1601–1613.
13. Franken, I. H. (2003). Drug craving and addiction: integrating psychological and neuropsychopharmacological approaches. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 27(4), 563-579
14. Koob, G. F., & LeMoal, M. (2001). Drug addiction, dysregulation of reward, and allostasis. Neuropsychopharmacology, 24, 97–129.
15. Volkow ND, Wang GJ, Fowler JS, et al. Decreased striatal dopaminergic responsiveness in detoxified cocaine-dependent subjects. Nature. 1997;386:830–3.
16. Koob GF, Le Moal M. Addiction and the brain antireward system. Annu Rev Psychol. 2008;59:29–53
17. El, S., Salah El, G., & Bashir, T. Z. (2004). High-risk relapse situations and self-efficacy: Comparison between alcoholics and heroin addicts. Addictive behaviors, 29(4), 753-758.
18. Hammerbacher, M., & Lyvers, M. (2006). Factors associated with relapse among clients in Australian substance disorder treatment facilities. Journal of substance use, 11(6), 387-394.
19. Marlatt, G.A. (1978) Craving for alcohol, loss of control and relapse: Cognitive behavioural analysis. In: Nathan, P.E., Marlatt, G.A., and Loberg, T. eds. Alcoholism: new directions in behavioural research and treatment. Plenum Press, New York, 271-314.
20. Marlatt, G.A., and Gordon, J.R. (1985). Relapse prevention: maintenance strategies in the treatment of addictive behaviors. Guilford Press, New York.
21. Townshend JM, Duka T . Attentional bias associated with alcohol cues: differences between heavy and occasional social drinkers. Psychopharmacology (Berl)2001;157:67-74.
22. Tiffany, S. T. (1990). A cognitive model of drug urges and drug-use behavior: role of automatic and nonautomatic processes. Psychological review, 97(2), 147.
23. Bar-Haim, Y., Lamy, D., Pergamin, L., Bakermans-Kranenburg, M. J., & van IJzendoorn, M. H. (2007). Threat-related attentional bias in anxious and nonanxious individuals: a meta-analytic study. Psychological bulletin, 133(1), 1.
24. McCusker CG Cognitive biases and addiction: an evolution in theory and method. Addiction 2001;96:47-56.