Addiction is driven by excessive goal-directed drug choice under negative affect: translational critique of habit and compulsion theory

Abstract

Drug addiction may be a goal-directed choice driven by excessive drug value in negative affective states, a habit driven by strong stimulus−response associations, or a compulsion driven by insensitivity to costs imposed on drug seeking. Laboratory animal and human evidence for these three theories is evaluated. Excessive goal theory is supported by dependence severity being associated with greater drug choice/economic demand. Drug choice is demonstrably goal-directed (driven by the expected value of the drug) and can be augmented by stress/negative mood induction and withdrawal-effects amplified in those with psychiatric symptoms and drug use coping motives. Furthermore, psychiatric symptoms confer risk of dependence, and coping motives mediate this risk. Habit theory of addiction has weaker support. Habitual behaviour seen in drug-exposed animals often does not occur in complex decision scenarios, or where responding is rewarded, so habit is unlikely to explain most human addictive behaviour where these conditions apply. Furthermore, most human studies have not found greater propensity to habitual behaviour in drug users or as a function of dependence severity, and the minority that have can be explained by task disengagement producing impaired explicit contingency knowledge. Compulsion theory of addiction also has weak support. The persistence of punished drug seeking in animals is better explained by greater drug value (evinced by the association with economic demand) than by insensitivity to costs. Furthermore, human studies have provided weak evidence that propensity to discount cost imposed on drug seeking is associated with dependence severity. These data suggest that human addiction is primarily driven by excessive goal-directed drug choice under negative affect, and less by habit or compulsion. Addiction is pathological because negative states powerfully increase expected drug value acutely outweighing abstinence goals.

Intact corticostriatal control of goal-directed action in Alcohol Use Disorder: a Pavlovian-to-instrumental transfer and outcome-devaluation study

“…Bayesian factors provided substantial evidence for the null hypothesis, indicating that individuals with AUD show no impairments integrating changes in experienced value with the action-outcome association. Although our findings are not in line with studies in animals 46 , evidence in humans is less convincing, as critically reviewed recently 47,48 . Animal studies have mostly relied on simple lever-press procedures to reveal impaired goal-directed control after chronic drug-exposure, which may produce stimulus-response "drug-habits" by design: recent evidence suggests that addiction-like behavior can emerge even when rats have to solve complex puzzles, which prevents drug seeking to become habitual, and that drug seeking remained under ventral striatal control 49 .…”

Habitual Preference for the Nondrug Reward in a Drug Choice Setting

“…Clearly, more research is needed to understand why choice behavior between drug and nondrug rewards becomes habitual and inflexible in our conditions in comparison to other choice studies. This question is all the more important because growing evidence in humans suggests that habit formation occurs rarely, if at all, in similar laboratory drug choice settings (Hogarth, 2020). One major difference between these two sets of choice studies, in addition to species-specific differences, is that in human drug choice studies, people preferred the drug option over the nondrug option while in our and other studies, rats showed the opposite preference.…”

Relative expected value of drugs versus competing rewards underpins vulnerability to and recovery from addiction

“…Unified economic decision making accounts of addiction have attempted to reconcile these competing theories by suggesting that all of the secondary processes might promote drugseeking via their impact on the expected relative value of the drug compared to competing nondrug alternative rewards, that is, by biasing preferential choice towards these rewards [5,6,10,22,23]. On this view, addiction is driven by a single process -the relative expected value ascribed to the drug versus to non-drug rewards -but this process can be influenced by a multitude of factors.…”

“…On the basis of these outcome devaluation studies, human dependence severity does not appear to be associated with a propensity to habit learning (insensitivity to drug devaluation). Other studies not included in Table 1, which tested whether drug users versus non-user control participants differ in their sensitivity to devaluation manipulations have similarly failed to find any consistent group difference, again providing little or no evidence for habit theory [22,[47][48][49]. Table 1 column 8 lists studies that measured the impact of imposing costs on drug choice, to test compulsion theory.…”