Cognitive Alterations in Addictive Disorders: A Translational Approach

The cognitive decline in people with substance use disorders is well known and can be found during both the dependence and drug abstinence phases. At the clinical level, cognitive decline impairs the response to addiction treatment and increases dropout rates. It can be irreversible, even after the end of drug abuse consumption. Improving our understanding of the molecular and cellular alterations associated with cognitive decline could be essential to developing specific therapeutic strategies for its treatment. Developing animal models to simulate drug abuse-induced learning and memory alterations is critical to continue exploring this clinical situation. The main aim of this review is to summarize the most recent evidence on cognitive impairment and the associated biological markers in patients addicted to some of the most consumed drugs of abuse and in animal models simulating this clinical situation. The available information suggests the need to develop more studies to further explore the molecular alterations associated with cognitive impairment, with the ultimate goal of developing new potential therapeutic strategies.

The Interaction of Inflammatory Markers and Alcohol-Use on Cognitive Function in Korean Male Firefighters

OBJECTIVE

Cognitive functions have been shown to become impaired due to alcoholism. Recently, neuroinflammation gained attention for playing a role in the neurotoxic effect of alcohol. However, there is limited data on the relationship between alcohol and cognitive function, based on the mechanism of inflammation. This study examined whether the interaction between alcohol use and pro-inflammatory biomarkers is related to cognitive function in Korean male firefighters.

METHODS

A total of 474 firefighters were assessed for alcohol-related problems using CAGE, cognitive functions, and pro-inflammatory biomarkers (CRP, IL-6, TNF-α). Sequential multiple regression analyses were conducted to determine if inflammatory markers moderate the relationship between alcohol use and cognitive function.

RESULTS

Only a decreased attentional function was associated with the interaction of alcohol use and inflammatory markers, after controlling for age, sex, body mass index, lipid profiles, smoking, depression, fatigue, self-reported hypertension, diabetes, and musculoskeletal problems.

CONCLUSION

This study revealed that the interaction between alcohol use and inflammation is related to attentional function in Korean male firefighters. Additionally, this cross-sectional study suggests that diminishing attention, related to alcohol use, may be based on the mechanism of inflammation.

Evaluation of the Use of an Inorganic Bone Matrix in the Repair of Bone Defects in Rats Submitted to Experimental Alcoholism

To assess the effects of chronic alcoholism on the repair of bone defects associated with xenograft. Forty male rats were distributed in: control group (CG, n = 20) and experimental group (EG, n = 20), which received 25% ethanol ad libitum after a period of adaptation. After 90 days of liquid diet, the rats were submitted to 5.0-mm bilateral craniotomy on the parietal bones, subdividing into groups: CCG (control group that received only water with liquid diet and the defect was filled with blood clot), BCG (control group that received only water with liquid diet and the defect was filled with biomaterial), CEG (alcoholic group that received only ethanol solution 25% v/v with liquid diet and the defect was filled with blood clot), and BEG (alcoholic group that received only ethanol solution 25% v/v with liquid diet and the defect was filled with biomaterial). In the analysis of body mass, the drunk animals presented the lowest averages in relation to non-drunk animals during the experimental period. Histomorphologically all groups presented bone formation restricted to the defect margins at 60 days, with bone islets adjacent to the BCG biomaterial particles. CEG showed significant difference compared to BEG only at 40 days (17.42 ± 2.78 vs. 9.59 ± 4.59, respectively). In the birefringence analysis, in early periods all groups showed red-orange birefringence turning greenish-yellow at the end of the experiment. The results provided that, regardless of clinical condition, i.e., alcoholic or non-alcoholic, in the final period of the experiment, the process of bone defect recomposition was similar with the use of xenograft or only clot.

Adult-Life Alcohol Consumption and Age-Related Cognitive Decline from Early Adulthood to Late Midlife

AIMS

Alcohol consumption is a modifiable and plausible risk factor for age-related cognitive decline but more longitudinal studies investigating the association are needed. Our aims were to estimate associations of adult-life alcohol consumption and consumption patterns with age-related cognitive decline.

METHODS

We investigated the associations of self-reported adult-life weekly alcohol consumption and weekly extreme binge drinking (≥10 units on the same occasion) with changes in test scores on an identical validated test of intelligence completed in early adulthood and late midlife in 2498 Danish men from the Lifestyle and Cognition Follow-up study 2015. Analyses were adjusted for year of birth, retest interval, baseline IQ, education and smoking.

RESULTS

Men with adult-life alcohol consumption of more than 28 units/week had a larger decline in IQ scores from early adulthood to late midlife than men consuming 1-14 units/week (B29-35units/week = -3.6; P < 0.001). Likewise, a 1-year increase in weekly extreme binge drinking was associated with a 0.12-point decline in IQ scores (P < 0.001). Weekly extreme binge drinking explained more variance in IQ changes than average weekly consumption. In analyses including mutual adjustment of weekly extreme binge drinking and average weekly alcohol consumption, the estimated IQ decline associated with extreme binge drinking was largely unaffected, whereas the association with weekly alcohol consumption became non-significant.

CONCLUSIONS

Adult-life heavy alcohol consumption and extreme binge drinking appear to be associated with larger cognitive decline in men. Moreover, extreme binge drinking may be more important than weekly alcohol consumption in relation to cognitive decline.

Peripheral proinflammatory markers are upregulated in abstinent alcohol-dependent patients but are not affected by cognitive bias modification: Preliminary findings

BACKGROUND

Inflammatory pathways are known to be negatively affected in patients with alcohol use disorder (AUD). Cognitive bias modification (CBM), an emerging behavioral treatment that involves the 're-training' of cognitive biases using computerized tasks, has been reported to reduce alcohol craving and relapse rates. The aim of this study was to compare peripheral concentrations of the proinflammatory biomarkers IL-18, IL-6, IL-1β, TNF-α and CRP in AUD patients versus controls and to identify whether CBM treatment affected these biomarkers in AUD patients.

METHODS

This 3-week double-blind randomized controlled study tested 36 male abstinent AUD patients receiving CBM or placebo-training, who were also compared to 18 male healthy controls. The approach avoidance task (AAT) was used to test the AUD patients before and after training. CBM training took place over 6 sessions, using a joystick-based approach-avoidance task. Blood samples were collected after the pre- and post-AAT test sessions for the AUD groups, and during an outpatient appointment with the controls.

RESULTS

AUD patients, versus controls, presented with significantly higher plasma levels of TNF- α (P < 0.0001) and CRP (P = 0.0031). No changes in the CBM versus placebo groups were noted in IL-18, TNF-α and CRP concentrations following pre-post change or within group pretest- posttest analysis. IL-6 and IL-1β levels fell under the lower detection limit, thus were not included in the final analyses.

CONCLUSIONS

This study confirms that the inflammatory system is altered in AUD. This was the first study that investigated whether CBM training affected proinflammatory markers in AUD patients.

The Interplay of Inflammatory Processes and Cognition in Alcohol Use Disorders-A Systematic Review

Rationale: Of late, evidence emerges that the pathophysiology of psychiatric diseases and their affiliated symptomatologies are at least partly contributable to inflammatory processes. Also in alcohol use disorders (AUD), this interaction is strongly apparent, with severely immunogenic liver cirrhosis being one of the most critical sequelae of chronic abusive drinking. This somatic immune system activation negatively impacts brain functioning, and additionally, alcohol abuse appears to have a direct detrimental effect on the brain by actively stimulating its immune cells and responses. As cognitive decline majorly contributes to AUD's debility, it is important to know to what extent impairment of cognitive functioning is due to these (neuro-)inflammatory aberrations. Method: We hereby summarize the current existing literature on the interplay between AUD, inflammation, and cognition in a systematic review according to the PRISMA-P guidelines for the systematic review. Main findings: Although literature on the role of inflammation in alcohol use-related cognitive deficiency remains scarce, current findings indicate that pro-inflammatory processes indeed result in exacerbation of several domains of cognitive deterioration. Interestingly, microglia, the immune cells of the brain, appear to exert initial compensatory neuroprotective functionalities upon acute ethanol exposure while chronic alcohol intake seems to attenuate these responses and overall microglial activity. Conclusion: As these results indicate inflammation to be of importance in cognitive impairment following alcohol consumption and might as such provide alternate therapeutic avenues, a considerable increase in research efforts in this domain is urgently required.

N-acetyl cysteine in the treatment of alcohol use disorder in patients with liver disease: Rationale for further research

INTRODUCTION

Alcoholic liver disease (ALD) is the leading cause of alcohol-related death and one of the most common forms of liver disease. Abstinence from alcohol is crucial to reducing morbidity and mortality associated with the disease. However, there are few pharmacotherapies for alcohol use disorder suitable for those with significant liver disease.

AREAS COVERED

This paper presents a rationale for investigating the use of N-acetyl cysteine (NAC) to promote abstinence or reduce heavy alcohol consumption for patients with an alcohol use disorder, particularly in the presence of liver disease. NAC is an antioxidant with glutamatergic modulating and anti-inflammatory properties. Evidence is emerging that oxidative stress, neuro-inflammation and dysregulation of glutamatergic neurotransmission play a key role in alcohol use disorder. Similarly, oxidative stress is known to contribute to ALD. We outline the studies that have investigated NAC to reduce alcohol consumption including preclinical and clinical studies. We also review the evidence for NAC in other addictions as well as psychiatric and physical comorbidities associated with alcohol use disorders.

EXPERT OPINION

NAC is low cost, well-tolerated and could have promise for the treatment of alcohol use disorder in the presence of liver disease. Clinical trials directly examining efficacy in this population are required.