Ethanol-Induced Antinociception in Rodents: Role of the Cholinergic and Opioidergic Systems

Pain-induced alterations in the dynorphinergic system within the mesocorticolimbic pathway: Implication for alcohol addiction

Latest studies have revealed that pain negatively impacts on reward processing and motivation leading to negative affective states and stress. These states not only reduce quality of life of patients by increasing the appearance of psychiatric comorbidities, but also have an important impact on vulnerability to drug abuse, including alcohol. In fact, clinical, epidemiological but also preclinical studies have revealed that the presence of pain is closely related to alcohol use disorders (AUDs). All this evidence suggests that pain is a factor that increases the risk of suffering AUD, predicting heavy drinking behavior and relapse drinking in those patients with a previous history of AUD. The negative consequences of chronic pain and its impact on stress and AUD are likely mediated by alterations in the central nervous system, especially in the stress and reward systems. Therefore, pain and stress impact on dopaminergic mesolimbic pathway can lead to an increase in drug abuse liability. In this mini review we analyze the interaction between pain, stress, and alcohol addiction, and how dynamic changes in the kappa opioid system might play a crucial role in the development of compulsive alcohol drinking in chronic pain patients.

A Reciprocal Model of Pain and Substance Use: Transdiagnostic Considerations, Clinical Implications, and Future Directions

Pain and substance use are highly prevalent and co-occurring conditions that continue to garner increasing clinical and empirical interest. Although nicotine and tobacco, alcohol, and cannabis each confer acute analgesic effects, frequent or heavy use may contribute to the development and progression of chronic pain, and pain may be heightened during abstinence. Additionally, pain can be a potent motivator of substance self-administration, and it may contribute to escalating use and poorer substance-related treatment outcomes. We integrated converging lines of evidence to propose a reciprocal model in which pain and substance use are hypothesized to interact in the manner of a positive feedback loop, resulting in the exacerbation and maintenance of both conditions over time. Theoretical mechanisms in bidirectional pain-substance use relations are reviewed, including negative reinforcement, social cognitive processes, and allostatic load in overlapping neural circuitry. Finally, candidate transdiagnostic factors are identified, and we conclude with a discussion of clinical implications and future research directions.

Interrelations between pain and alcohol: An integrative review

Pain and alcohol use are both highly prevalent in the general population, and pain-alcohol interrelations are of increasing empirical interest. Previous research has identified associations between pain and alcohol dependence, and the current review provides novel contributions to this emerging domain by incorporating studies that have tested relations between pain and low-to-moderate alcohol consumption, and by identifying potential psychosocial mechanisms of action. Specifically, we sought to integrate evidence of pain-alcohol relations derived from two directions of empirical inquiry (i.e., effects of alcohol on pain and effects of pain on alcohol use) across psychological, social, and biological literatures. We observed converging evidence that associations between alcohol consumption and pain may be curvilinear in nature. Whereas moderate alcohol use was observed to be associated with positive pain-related outcomes (e.g., greater quality of life), excessive drinking and alcohol use disorder appear to be associated with deleterious pain-related outcomes (e.g., greater pain severity). We also observed evidence that alcohol administration confers acute pain-inhibitory effects, and that situational pain may motivate alcohol consumption (e.g., drinking for pain-coping). Future research can inform theoretical and clinical applications through examination of temporal relations between pain and alcohol consumption, tests of hypothesized mechanisms, and the development of novel interventions.