Incubation of alcohol craving as it naturally occurs in a developmentally diverse sample of dependent and nondependent drinkers

Reductions in WHO risk drinking levels correlate with alcohol craving among individuals with alcohol use disorder

BACKGROUND

Abstinence has historically been considered the preferred goal of alcohol use disorder (AUD) treatment. However, most individuals with AUD do not want to abstain and many are able to reduce their drinking successfully. Craving is often a target of pharmacological and behavioral interventions for AUD, and reductions in craving may signal recovery. Whether reductions in drinking during AUD treatment are associated with reductions in craving has not been well examined.

METHODS

We conducted secondary analyses of data from three AUD clinical trials (N's= 1327, 346, and 200). Drinking reductions from baseline to the end of treatment were measured as changes in World Health Organization (WHO) risk drinking levels; alcohol craving was measured using validated self-report measures. Regression analyses tested whether drinking reductions were associated with end-of-treatment craving reductions; moderation analyses tested whether associations between drinking reduction and end-of-treatment craving differed across AUD severity.

RESULTS

Reductions of at least 1 or at least 2 WHO risk drinking levels were associated with lower craving (all p's < 0.05). Results were substantively similar after removing abstainers at the end-of-treatment. Associations between drinking reductions and craving were generally not moderated by AUD severity.

CONCLUSIONS

Individuals with WHO risk drinking level reductions reported significantly lower craving, as compared to those who did not achieve meaningful reductions in drinking. The results demonstrate the utility of WHO risk drinking levels as AUD clinical trial endpoints and provide evidence that drinking reductions mitigate craving.

Alcohol cues increase behavioral economic demand and craving for alcohol in nontreatment-seeking and treatment-seeking heavy drinkers

BACKGROUND

Behavioral economic research has revealed significant increases in alcohol demand following exposure to alcohol-related cues. Prior research has focused exclusively on nontreatment-seeking heavy drinkers, included only male participants, or used heterogeneous methods. The current studies sought to replicate and extend existing findings in treatment-seeking and nontreatment-seeking heavy drinkers while also examining sex effects and moderation by alcohol use disorder (AUD) severity.

METHODS

Study 1 included 117 nontreatment-seeking heavy drinkers (51.5% women; M age 34.69; 56.4% AUD+), and Study 2 included 89 treatment-seeking heavy drinkers with AUD (40.4% women; M age = 41.35). In both studies, alcohol demand was measured using a hypothetical alcohol purchase task (APT), and subjective alcohol craving was measured using visual analog scales. Measures were collected following exposure to neutral (water) cues in a standard room and alcohol cues in a bar lab.

RESULTS

Alcohol demand (intensity, Omax , breakpoint, and elasticity) and craving were significantly increased following alcohol cues compared to neutral cues (ps < 0.005) with effect sizes ranging from small to large (ηp 2  = 0.074-0.480). Participants with AUD (Study 1) or with higher AUD severity (Study 2) reported higher craving and higher demand for most indices (i.e., main effects; ps < 0.032, ηp 2  = 0.043-0.239). A larger alcohol cue increase in Omax was found for AUD+ participants in Study 1 compared to non-AUD participants (p = 0.028, ηp 2  = 0.041) but not for any other indices in Study 1 or Study 2. There were no significant sex effects.

CONCLUSIONS

These findings replicate and extend prior research by offering additional insight into alcohol cue effects on the reinforcing value of alcohol and subjective motivation to drink. The results also suggest that sex and AUD severity do not meaningfully impact cue effects across most indices of demand.

Peer-elicited alcohol craving in adolescents and emerging adults: Bridging the laboratory and natural environment

BACKGROUND

Although peers figure prominently in developmental models of alcohol use, our understanding of the influence of peer social context in cue reactivity paradigms with adolescents and emerging adults in the human laboratory and the natural environment is limited. This study tested associations between alcohol craving among youth in the human laboratory using alcohol-related images, with and without peers, and in the natural environment using ecological momentary assessment (EMA).

METHODS

Data for this preregistered secondary analysis were collected prior to randomization in two medication trials (N = 115). Participants completed an image cue exposure paradigm at the baseline laboratory session followed by approximately 7 days of EMA.

RESULTS

In the laboratory, model-based mean comparisons from multilevel models (MLMs) showed that all drinking images elicited greater craving than neutral images. No differences were observed across the three image categories containing alcohol. Image category by age interactions demonstrated that, compared to older youth, younger youth displayed lower craving in response to neutral versus social drinking context with peers images and older, compared to younger, youth displayed higher craving in response to nonsocial drinking images versus social drinking contexts with peers images. In the natural environment, craving was greatest when youth were in the presence of alcohol-using peers and alcohol-related cues, regardless of age. Laboratory craving to alcohol images was positively associated with craving in the natural environment.

CONCLUSIONS

For youth, peers are a salient social context associated with increased craving, particularly in the natural environment. Laboratory cue reactivity to alcohol images predicted real-world craving, further supporting the ecological validity of this paradigm in youth.

Alcohol craving in the natural environment: Moderating roles of cue exposure, drinking, and alcohol sensitivity

Effects of cue exposure and alcohol consumption (e.g., priming doses) on craving for alcohol have been examined in largely separate literature, limiting what is known about their potential interaction. Individuals with low alcohol sensitivity, a known risk factor for alcohol use disorder (AUD), exhibit stronger cue-elicited craving than their higher-sensitivity (HS) peers in both laboratory and real-world contexts. Here, underage drinkers (N = 155) completed a 21-day ecological momentary assessment (EMA) protocol in which they recorded exposure to alcohol cues and levels of craving during both nondrinking and postdrinking moments. Multilevel modeling detected a significant interaction of cue exposure and postdrinking status on craving. Cue-induced craving was increased in postdrinking moments compared to nondrinking moments. Contrary to prediction, cue-elicited increase in craving during nondrinking moments was stronger in participants reporting higher sensitivity to alcohol. In the presence of cues, lower sensitivity was robustly related to craving intensity in the postdrinking state but unrelated to craving during nondrinking moments. Craving during drinking episodes in the natural environment is magnified by the presence of alcohol cues, potentially contributing to the maintenance or acceleration of drinking episodes. Moreover, lower-sensitivity drinkers may be particularly susceptible to the combined effects of cue exposure and postdrinking status on alcohol craving. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Preventing incubation of drug craving to treat drug relapse: from bench to bedside

In 1986, Gawin and Kleber reported a progressive increase in cue-induced drug craving in individuals with cocaine use disorders during prolonged abstinence. After years of controversy, as of 2001, this phenomenon was confirmed in rodent studies using self-administration model, and defined as the incubation of drug craving. The intensification of cue-induced drug craving after withdrawal exposes abstinent individuals to a high risk of relapse, which urged us to develop effective interventions to prevent incubated craving. Substantial achievements have been made in deciphering the neural mechanisms, with potential implications for reducing drug craving and preventing the relapse. The present review discusses promising drug targets that have been well investigated in animal studies, including some neurotransmitters, neuropeptides, neurotrophic factors, and epigenetic markers. We also discuss translational exploitation and challenges in the field of the incubation of drug craving, providing insights into future investigations and highlighting the potential of pharmacological interventions, environment-based interventions, and neuromodulation techniques.

Profiling prefrontal cortex protein expression in rats exhibiting an incubation of cocaine craving following short-access self-administration procedures

INTRODUCTION

Incubation of drug-craving refers to a time-dependent increase in drug cue-elicited craving that occurs during protracted withdrawal. Historically, rat models of incubated cocaine craving employed extended-access (typically 6 h/day) intravenous drug self-administration (IV-SA) procedures, although incubated cocaine craving is reported to occur following shorter-access IV-SA paradigms. The notoriously low-throughput of extended-access IV-SA prompted us to determine whether two different short-access IV-SA procedures akin to those in the literature result in qualitatively similar changes in glutamate receptor expression and the activation of downstream signaling molecules within prefrontal cortex (PFC) subregions as those reported previously by our group under 6h-access conditions.

METHODS

For this, adult, male Sprague-Dawley rats were trained to intravenously self-administer cocaine for 2 h/day for 10 consecutive days (2-h model) or for 6 h on day 1 and 2 h/day for the remaining 9 days of training (Mixed model). A sham control group was also included that did not self-administer cocaine.

RESULTS

On withdrawal day 3 or 30, rats were subjected to a 2-h test of cue-reinforced responding in the absence of cocaine and a time-dependent increase in drug-seeking was observed under both IV-SA procedures. Immunoblotting of brain tissue collected immediately following the cue test session indicated elevated phospho-Akt1, phospho-CaMKII and Homer2a/b expression within the prelimbic subregion of the PFC of cocaine-incubated rats. However, we failed to detect incubation-related changes in Group 1 metabotropic glutamate receptor or ionotropic glutamate receptor subunit expression in either subregion.

DISCUSSION

These results highlight further a role for Akt1-related signaling within the prelimbic cortex in driving incubated cocaine craving, and provide novel evidence supporting a potential role also for CaMKII-dependent signaling through glutamate receptors in this behavioral phenomenon.

Factors modulating the incubation of drug and non-drug craving and their clinical implications

It was suggested in 1986 that cue-induced cocaine craving increases progressively during early abstinence and remains high during extended periods of time. Clinical evidence now supports this hypothesis and that this increase is not specific to cocaine but rather generalize across several drugs of abuse. Investigators have identified an analogous incubation phenomenon in rodents, in which time-dependent increases in cue-induced drug seeking are observed after abstinence from intravenous drug or palatable food self-administration. Incubation of craving is susceptible to variation in magnitude as a function of biological and/or the environmental circumstances surrounding the individual. During the last decade, the neurobiological correlates of the modulatory role of biological (sex, age, genetic factors) and environmental factors (environmental enrichment and physical exercise, sleep architecture, acute and chronic stress, abstinence reinforcement procedures) on incubation of drug craving has been investigated. In this review, we summarized the behavioral procedures adopted, the key underlying neurobiological correlates and clinical implications of these studies.

Translational opportunities in animal and human models to study alcohol use disorder

Animal and human laboratory paradigms offer invaluable approaches to study the complex etiologies and mechanisms of alcohol use disorder (AUD). We contend that human laboratory models provide a "bridge" between preclinical and clinical studies of AUD by allowing for well-controlled experimental manipulations in humans with AUD. As such, examining the consilience between experimental models in animals and humans in the laboratory provides unique opportunities to refine the translational utility of such models. The overall goal of the present review is to provide a systematic description and contrast of commonly used animal paradigms for the study of AUD, as well as their human laboratory analogs if applicable. While there is a wide breadth of animal species in AUD research, the paradigms discussed in this review rely predominately on rodent research. The overarching goal of this effort is to provide critical analysis of these animal models and to link them to human laboratory models of AUD. By systematically contrasting preclinical and controlled human laboratory models, we seek to identify opportunities to enhance their translational value through forward and reverse translation. We provide future directions to reconcile differences between animal and human work and to improve translational research for AUD.

How adolescents' working memory abilities relate to their alcohol craving in real-life contexts depends on biological sex

AIM

We sought to elucidate whether stress, peers, and in vivo (i.e., direct) alcohol cues elicit alcohol craving in daily life among adolescents and to test whether individual variation in working memory function and biological sex alters these associations.

METHODS

We leveraged ecological momentary assessment (EMA) to examine momentary associations between stress, peers, and direct alcohol cues with craving, assessed as "urge to drink alcohol," among 86 male (51.2 %) and female (48.8 %) frequent drinkers (i.e., two or more drinking days per week). Participants were ages 14-24 years (M = 20.7 years, SD = 2.1). Participants completed EMA throughout the day for about one week prior to randomization to a treatment condition for an AUD clinical trial. Pre-registered, secondary analyses focused on craving for assessments when adolescents were not drinking, and assessments occurring after drinking on drinking days were removed. Working memory performance was assessed in the laboratory via the Memory for Words subtest of the Woodcock-Johnson III Tests of Cognitive Abilities.

RESULTS

Craving was heightened at more stressful moments and when adolescents were with their peers and in the presence of direct alcohol cues. Working memory function was not related to craving but altered the relation of momentary stress, peers, and cues with craving once biological sex-related differences were considered. Females generally had lower craving than males, but working memory function served to buffer against stress-induced craving for males.

CONCLUSIONS

Higher working memory function buffered the in-the-moment relation of stress with alcohol craving for males but not females.

Neural mechanisms underlying incubation of methamphetamine craving: A mini-review

Cue-induced drug craving and seeking progressively increases during abstinence. This "incubation of drug craving" phenomenon has been observed in both laboratory animals and humans. Preclinical studies identified several neural mechanisms underlying incubation of drug craving after forced abstinence, primarily focusing on cocaine. Recently, studies started focusing on another powerful psychostimulant, methamphetamine (Meth), and developed new incubation procedures (choice-induced and punishment-induced abstinence). Here, we review mechanistic studies at the circuit, synaptic and molecular levels on incubation of Meth craving. First, we provide an overview of neural adaptations associated with prolonged forced abstinence after extended-access Meth self-administration. Next, we review studies examining the causal roles of discrete brain regions and associated circuits, glutamate transmission, histone deacetylase 5 and oxytocin in incubation of Meth craving after forced abstinence. Lastly, we review causal and correlational studies examining the mechanisms underlying incubation of Meth craving after choice-induced voluntary abstinence and punishment-induced abstinence, respectively. We conclude by discussing the translational potential of these mechanistic studies in Meth relapse prevention in human drug users.