Toward the Identification of a Specific Psychopathology of Substance Use Disorders

Listening to the Data: Computational Approaches to Addiction and Learning

Computational approaches hold great promise for identifying novel treatment targets and creating translational therapeutics for substance use disorders. From circuitries underlying decision-making to computationally derived neural markers of drug-cue reactivity, this review is a summary of the approaches to data presented at our 2023 Society for Neuroscience Mini-Symposium. Here, we highlight data- and hypothesis-driven computational approaches that recently afforded advancements in addiction and learning neuroscience. First, we discuss the value of hypothesis-driven algorithmic modeling approaches, which integrate behavioral, neural, and cognitive outputs to refine hypothesis testing. Then, we review the advantages of data-driven dimensionality reduction and machine learning methods for uncovering novel predictor variables and elucidating relationships in high-dimensional data. Overall, this review highlights recent breakthroughs in cognitive mapping, model-based analysis of behavior/risky decision-making, patterns of drug taking, relapse, and neuromarker discovery, and showcases the benefits of novel modeling techniques, across both preclinical and clinical data.

Psychedelic Treatments for Substance Use Disorder and Substance Misuse: A Mixed Methods Systematic Review

Renewed interest in psychedelic substances in the 21st century has seen the exploration of psychedelic treatments for various psychiatric disorders including substance use disorder (SUD). This review aimed to assess the effectiveness of psychedelic treatments for people with SUD and those falling below diagnostic thresholds (i.e. substance misuse). We systematically searched 11 databases, trial registries, and psychedelic organization websites for empirical studies examining adults undergoing psychedelic treatment for SUD or substance misuse, published in the English language, between 2000 and 2021. Seven studies investigating treatment using psilocybin, ibogaine, and ayahuasca, alone or adjunct with psychotherapy reported across 10 papers were included. Measures of abstinence, substance use, psychological and psychosocial outcomes, craving, and withdrawal reported positive results, however, this data was scarce among studies examining a wide range of addictions including opioid, nicotine, alcohol, cocaine and unspecified substance. The qualitative synthesis from three studies described subjective experience of psychedelic-assisted treatments enhanced self-awareness, insight, and confidence. At present, there is no sufficient research evidence to suggest effectiveness of any of the psychedelics on any specific substance use disorder or substance misuse. Further research using rigorous effectiveness evaluation methods with larger sample sizes and longer-term follow-up is required.

Characteristics of Stress Sensitivity in Heroin Use Disorder Patients during Their Opioid Agonist Treatment

In the present study, performed on a sample of Heroin Use Disorder (HUD) patients undergoing Opioid Agonist Treatment (OAT), we attempted to explore the relationships between stress sensitivity and heroin addiction-related clinical aspects. HUD patients' stress sensitivity was evaluated with the Heroin/PTSD-Spectrum questionnaire (H/PSTD-S). The Drug Addiction History Questionnaire (DAH-Q), the Symptomatological Check List-90 (SCL-90), and The Behavioural Covariate of Heroin Craving inventory (CRAV-HERO) were all used, as were the Deltito Subjective Wellness Scale (D-SWS), a self-report scale evaluating subjective well-being; the Cocaine Problem Severity Index (CPSI), a questionnaire determining the extent of a cocaine problem; and the Marijuana Craving Questionnaire (MC-Q), an instrument assessing craving for cannabinoids. We checked correlations between stress sensitivity and the extent of HUD clinical features and compared patients with and without problematic stress sensitivity. H/PTSD-S was positively correlated with patients' income, altered mental status, legal problems, the lifetime different treatments index, the current treatment load index, and all SCL-90 indexes and factors. Regarding subjective well-being, stress sensitivity negatively correlated with the contrast best week (last five years) index. Patients with high-stress sensitivity were females with a low income. They exhibited a more severe mental status at treatment entry, greater difficulty in working adaptation, and legal problems during treatment. Additionally, these patients showed a higher level of psychopathology, more impairment in well-being, and more risky behaviours during treatment. Stress sensitivity, as H/PTSD-S, must be considered an outcome of HUD. HUD's addiction history and clinical features are significant risk factors for H/PTSD-S. Therefore, social and behavioural impairment in HUD patients could be considered the clinical expression of the H/PTSD spectrum. In summary, the long-term outcome of HUD is not represented by drug-taking behaviours. Rather, the inability to cope with the contingent environmental conditions is the key feature of such a disorder. H/PTSD-S, therefore, should be seen as a syndrome caused by an acquired inability (increased salience) concerning regular (daily) life events.

The impact of OPRM1's genetic polymorphisms on methadone maintenance treatment in opioid addicts: a systematic review

Aim: Methadone is a long-acting opioid receptor agonist. It is prescribed to patients with opioid-related use disorders. The OPRM1 gene encodes for methadone's main receptor. It appears that polymorphisms in OPRM1 may affect the efficacy of methadone maintenance treatment (MMT). Objective: Our purpose was to identify all relevant published papers dealing with the impact ofOPRM1's SNPs  on MMT's efficacy and to summarize results in order to evaluate the relevance of conducting pretherapeutic genotyping in opioid addicts prior to the onset of MMT. Methods: MEDLINE, PsychINFO and Scopus databases were systematically searched up to 1 January  2018 with no year restrictions using the following keyword combination (MMT) AND (mu or OPRM or mu opioid receptors or SNP or polymorphism or gene). Endpoint of the included studies had to be the impact of OPRM1 gene polymorphisms on the efficacy of MMT and/or methadone required doses during MMT. All abstracts were reviewed to assess papers’ relevance. Studies conducted on animals and duplicate papers were excluded. Results: Our literature search identified 438 articles. Eight of them were included in our systematic review. The total number of included participants was equal to 2170, of whom 1718 underwent MMT. One study reported results of a randomized controlled trial. Three were designed as case–control studies and four as cross-sectional studies. rs1799971 (A118G) was the most studied allele. Results were divergent. Other SNPs might affect MMT's efficacy, however they were scarcely studied. Conclusion: Genotyping patients with opioid-related use disorders is a promising way to reach a better outcome in patients willing to be on MMT. Focusing on OPRM1 solely should be balanced since polymorphisms in other genes implicated in methadone pharmacodynamics and/or pharmacokinetics may conjunctly affect the efficacy of MMT. Recommendations cannot be enunciated for the moment.

Further Evidence of a Specific Psychopathology of Addiction. Differentiation from Other Psychiatric Psychopathological Dimensions (Such as Obesity)

Introduction: In this study, we used a symptomatology checklist (SCL-90) to substantiate the hypothesis that Substance Use Disorder (SUD) has its own five-dimensional psychopathology. The aim of the present study was to test whether this psychopathology can be differentiated from other psychiatric psychopathological dimensions (such as obesity). Methods: The severity and frequency of each of the five dimensions were investigated, at univariate and multivariate levels, by comparing 972 Heroin Use Disorder (HUD) patients (83.5% male, mean age 30.12 ± 6.6, range: 16–59) and 106 obese individuals (50.0% male, mean age 37.59 ± 7.6, range: 24–52). The correlations between the Body Mass Index (BMI) of obese individuals with these psychopathological dimensions were also studied. Results: Obese individuals showed higher SCL-90 total scores, global severity index scores, number of items rated positively, and positive symptoms distress index scores than HUD patients. The severity of all psychopathological dimensions was significantly higher in obese individuals. Discriminant analysis showed that Panic-Anxiety and Violence-Suicide severity were more frequent in obese patients, sufficiently so to allow differentiation between HUD (lower severity) and obese individuals (greater severity). At the reclassification level, 70.8% of obese individuals in the sample were reclassified as HUD patients. Psychopathological subtypes characterized by Panic-Anxiety and Violence-Suicide typology were more frequent in obese patients and sufficiently so as to discriminate between groups. Of obese patients, 47.2% were reclassified as HUD patients. The severity of the Worthlessness-Being Trapped dimension was sufficient to predict the BMI of obese individuals. Conclusions: Our results suggest that the five-factor psychopathology found in HUD can discriminate between HUD and obese patients, but that there is an area of overlap between the forms of psychopathology found in SUD and those found in obese patients.