Substance use and spine density: a systematic review and meta-analysis of preclinical studies

The elucidation of synaptic density changes provides valuable insights into the underlying brain mechanisms of substance use. In preclinical studies, synaptic density markers, like spine density, are altered by substances of abuse (e.g., alcohol, amphetamine, cannabis, cocaine, opioids, nicotine). These changes could be linked to phenomena including behavioral sensitization and drug self-administration in rodents. However, studies have produced heterogeneous results for spine density across substances and brain regions. Identifying patterns will inform translational studies given tools that now exist to measure in vivo synaptic density in humans. We performed a meta-analysis of preclinical studies to identify consistent findings across studies. PubMed, ScienceDirect, Scopus, and EBSCO were searched between September 2022 and September 2023, based on a protocol (PROSPERO: CRD42022354006). We screened 6083 publications and included 70 for meta-analysis. The meta-analysis revealed drug-specific patterns in spine density changes. Hippocampal spine density increased after amphetamine. Amphetamine, cocaine, and nicotine increased spine density in the nucleus accumbens. Alcohol and amphetamine increased, and cannabis reduced, spine density in the prefrontal cortex. There was no convergence of findings for morphine's effects. The effects of cocaine on the prefrontal cortex presented contrasting results compared to human studies, warranting further investigation. Publication bias was small for alcohol or morphine and substantial for the other substances. Heterogeneity was moderate-to-high across all substances. Nonetheless, these findings inform current translational efforts examining spine density in humans with substance use disorders.

Cocaine self-administration behavior is associated with subcortical and cortical morphometry measures in individuals with cocaine use disorder

Background: Individual differences in gray-matter morphometry in the limbic system and frontal cortex have been linked to clinical features of cocaine use disorder (CUD). Self-administration paradigms can provide more direct measurements of the relationship between the regulation of cocaine use and gray-matter morphometry when compared to self-report assessments.Objectives: Our goal was to investigate associations with self-administration behavior in subcortical and cortical brain regions. We hypothesized the number of cocaine infusions self-administered would be correlated with gray-matter volumes (GMVs) in the striatum, amygdala, and hippocampus. Due to scarcity in human studies, we did not hypothesize subcortical directionality. In the frontal cortex, we hypothesized thickness would be negatively correlated with self-administered cocaine.Methods: We conducted an analysis of cocaine self-administration and structural MRI data from 33 (nFemales = 10) individuals with moderate-to-severe CUD. Self-administration lasted 60-minutes and cocaine (8, 16, or 32 mg/70 kg) was delivered on an FR1 schedule (5-minute lockout). Subcortical and cortical regression analyses were performed that included combined bilateral regions and age, experimental variables and use history as confounders.Results: Self-administered cocaine infusions were positively associated with caudal GMV (b = 0.18, p = 0.030) and negatively with putamenal GMV (b = -0.10, p = 0.041). In the cortical model, infusions were positively associated with insular thickness (b = 0.39, p = 0.008) and women appeared to self-administer cocaine more frequently (b = 0.23, p = 0.019).Conclusions: Brain morphometry features in the striatum and insula may contribute to cocaine consumption in CUD. These differences in morphometry may reflect consequences of prolonged use, predisposed vulnerability, or other possibilities.Clinical Trial Numbers: NCT01978431; NCT03471182.

Dysregulation of the endogenous cannabinoid system following opioid exposure

Rates of opioid-related deaths and overdoses in the United States are at record-high levels. Thus, novel neurobiological targets for the treatment of OUD are greatly needed. Given the close interaction between the endogenous opioid system and the endocannabinoid system (ECS), targeting the ECS may have therapeutic potential in OUD. The various components of the ECS, including cannabinoid receptors, their lipid-derived endogenous ligands (endocannabinoids [eCBs]), and the related enzymes, present potential targets for developing new medications in OUD treatment. The purpose of this paper is to review the clinical and preclinical literature on the dysregulation of the ECS after exposure to opioids. We review the evidence of ECS dysregulation across various study types, exposure protocols, and measurement protocols and summarize the evidence for dysregulation of ECS components at specific brain regions. Preclinical research has shown that opioids disrupt various ECS components that are region-specific. However, the results in the literature are highly heterogenous and sometimes contradictory, possibly due to variety of different methods used. Further research is needed before a confident conclusion could be made on how exposure to opioids can affect ECS components in various brain regions.

"Dysregulated not deficit": A qualitative study on symptomatology of ADHD in young adults

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is a common condition that often persists into adulthood, although data suggest that the current diagnostic criteria may not represent how the condition presents in adults. We aimed to use qualitative methods to better understand ADHD symptomatology in young adults, especially regarding attentional and emotional dysregulation.

METHODS

Nine focus groups involving young adults (aged 18-35 years; N = 43; 84% female; 86% US and Canada) with diagnoses of ADHD were conducted. Participants were asked about their perceptions of the current diagnostic criteria and how their symptoms have presented and changed over time. Data were analyzed using an interpretive phenomenological analysis framework.

RESULTS

Most participants reported that the diagnostic criteria did not accurately capture their experiences with ADHD. They reported struggling with attention dysregulation, including hyperfocusing, and emotional dysregulation, including rejection-sensitive dysphoria. Many participants believed that their changing environments and behavioral adaptations influenced how their symptoms presented into adulthood.

CONCLUSION

Current diagnostic criteria for ADHD may not capture the range of symptoms present in young adults. More research is needed to characterize attentional and emotional dysregulation in this population.

Discriminating cocaine use from other sympathomimetics using wearable electrocardiographic (ECG) sensors

BACKGROUND

Our group has established the feasibility of using on-body electrocardiographic (ECG) sensors to detect cocaine use in the human laboratory. The purpose of the current study was to test whether ECG sensors and features are capable of discriminating cocaine use from other non-cocaine sympathomimetics.

METHODS

Eleven subjects with cocaine use disorder wore the Zephyr BioHarness™ 3 chest band under six experimental (drug and non-drug) conditions, including 1) laboratory, intravenous cocaine self-administration, 2) after a single oral dose of methylphenidate, 3) during aerobic exercise, 4) during tobacco use (N=7 who smoked tobacco), and 5) during routine activities of daily inpatient living (unit activity). Three ECG-derived feature sets served as primary outcome measures, including 1) the RR interval (i.e., heart rate), 2) a group of ECG interval proxies (i.e., PR, QS, QT and QTc intervals), and 3) the full ECG waveform. Discriminatory power between cocaine and non-cocaine conditions for each of the three outcomes measures was expressed as the area under the receiver operating characteristics (AUROC) curve.

RESULTS

All three outcomes successfully discriminated cocaine use from unit activity, exercise, tobacco, and methylphenidate conditions with a mean AUROC values ranging from 0.66 to 0.99 and with least squares means values all statistically different/higher than 0.5 among all subjects [F(3, 99) = 3.38, p =0.02] and among those with tobacco use [F(4, 84) = 5.39, p = 0.0007].

CONCLUSIONS

These preliminary results support discriminatory power of wearable ECG sensors for detecting cocaine use.

Changes in synaptic markers after administration of ketamine or psychedelics: a systematic scoping review

Background

Ketamine and psychedelics have abuse liability. They can also induce "transformative experiences" where individuals experience enhanced states of awareness. This enhanced awareness can lead to changes in preexisting behavioral patterns which could be beneficial in the treatment of substance use disorders (SUDs). Preclinical and clinical studies suggest that ketamine and psychedelics may alter markers associated with synaptic density, and that these changes may underlie effects such as sensitization, conditioned place preference, drug self-administration, and verbal memory performance. In this scoping review, we examined studies that measured synaptic markers in animals and humans after exposure to ketamine and/or psychedelics.

Methods

A systematic search was conducted following PRISMA guidelines, through PubMed, EBSCO, Scopus, and Web of Science, based on a published protocol (Open Science Framework, DOI: 10.17605/OSF.IO/43FQ9). Both in vivo and in vitro studies were included. Studies on the following synaptic markers were included: dendritic structural changes, PSD-95, synapsin-1, synaptophysin-1, synaptotagmin-1, and SV2A.

Results

Eighty-four studies were included in the final analyses. Seventy-one studies examined synaptic markers following ketamine treatment, nine examined psychedelics, and four examined both. Psychedelics included psilocybin/psilocin, lysergic acid diethylamide, N,N-dimethyltryptamine, 2,5-dimethoxy-4-iodoamphetamine, and ibogaine/noribogaine. Mixed findings regarding synaptic changes in the hippocampus and prefrontal cortex (PFC) have been reported when ketamine was administered in a single dose under basal conditions. Similar mixed findings were seen under basal conditions in studies that used repeated administration of ketamine. However, studies that examined animals during stressful conditions found that a single dose of ketamine counteracted stress-related reductions in synaptic markers in the hippocampus and PFC. Repeated administration of ketamine also counteracted stress effects in the hippocampus. Psychedelics generally increased synaptic markers, but results were more consistently positive for certain agents.

Conclusion

Ketamine and psychedelics can increase synaptic markers under certain conditions. Heterogeneous findings may relate to methodological differences, agents administered (or different formulations of the same agent), sex, and type of markers. Future studies could address seemingly mixed results by using meta-analytical approaches or study designs that more fully consider individual differences.

Hypothalamic-pituitary-adrenal and autonomic response to psychological stress in abstinent alcohol use disorder individuals with and without depressive symptomatology

BACKGROUND

Stress and depression have each been associated with relapse risk. In clinical practice, chronic alcohol use is often accompanied by poor emotional and self-regulatory processes. Tonic and phasic changes in stress responsivity impact an individual's relapse risk to alcohol. A further complicating factor is the pervasive coexistence of depressive symptoms in those with Alcohol Use Disorder (AUD), where the contribution of depressive symptomatology to these processes is not well understood. Individuals with AUD (AD) (21 with and 12 without sub-clinical depressive symptoms) and 37 social drinking controls (16 with and 21 without sub-clinical depressive symptoms) as part of a more extensive study (Fox et al., 2019). All participants were exposed to two 5-min personalized guided imagery conditions (stress and neutral) in a randomized and counterbalanced order across consecutive days. Alcohol craving, negative mood, Stroop performance, and plasma measures (cortisol, adrenocorticotrophic hormone, and salivary alpha-amylase) were collected before and after imagery exposure.

RESULTS

Elevations in autonomic response (heart rate) to imagery (stress and neutral) were observed as a function of drinking (in both depressed and non-depressed individuals with alcohol use disorder compared with depressed and non-depressed social drinkers). Conversely, suppressed cortisol following stress was observed as a function of depressive symptomatology across both drinking groups. Individuals with comorbid AD and depressive symptoms demonstrated attenuated Adrenocorticotropic Hormone and poor Stroop performance compared with the other groups, indicating an interactive effect between drinking and depression on pituitary and inhibitory systems.

CONCLUSION

Sub-clinical depressive pathophysiology may be distinct from drinking severity and may alter relapse-related stress adaptations during protracted abstinence from alcohol.

Cholinergic system adaptations are associated with cognitive function in people recently abstinent from smoking: a (-)-[18F]flubatine PET study

The cholinergic system is a critical mediator of cognition in animals. People who smoke cigarettes exhibit cognitive deficits, especially during quit attempts. Few studies jointly examine the cholinergic system and cognition in people while trying to quit smoking. We used positron emission tomography (PET) brain imaging with the β2-subunit containing nicotinic acetylcholine receptor (β2*-nAChR) partial agonist radioligand (-)-[18F]flubatine and the acetylcholinesterase inhibitor physostigmine to jointly examine the cholinergic system, smoking status, and cognition. (-)-[18F]Flubatine scans and cognitive data were acquired from twenty people who recently stopped smoking cigarettes (aged 38 ± 11 years; 6 female, 14 male; abstinent 7 ± 1 days) and 27 people who never smoked cigarettes (aged 29 ± 8 years; 11 female, 16 male). A subset of fifteen recently abstinent smokers and 21 never smokers received a mid-scan physostigmine challenge to increase acetylcholine levels. Regional volume of distribution (VT) was estimated with equilibrium analysis at "baseline" and post-physostigmine. Participants completed a cognitive battery prior to (-)-[18F]flubatine injection and physostigmine administration assessing executive function (Groton Maze Learning test), verbal learning (International Shopping List test), and working memory (One Back test). Physostigmine significantly decreased cortical (-)-[18F]flubatine VT, consistent with increased cortical acetylcholine levels reducing the number of β2*-nAChR sites available for (-)-[18F]flubatine binding, at comparable magnitudes across groups (p values < 0.05). A larger magnitude of physostigmine-induced decrease in (-)-[18F]flubatine VT was significantly associated with worse executive function in people who recently stopped smoking (p values < 0.05). These findings underscore the role of the cholinergic system in early smoking cessation and highlight the importance of neuroscience-informed treatment strategies.

Neurotransmitter transporter occupancy following administration of centanafadine sustained-release tablets: A phase 1 study in healthy male adults

BACKGROUND

Centanafadine is an inhibitor of reuptake transporters for norepinephrine (NET), dopamine (DAT) and serotonin (SERT).

AIMS

This phase 1, adaptive-design positron emission tomography study investigated the occupancy time course of NET, DAT, and SERT and the relationship to centanafadine plasma concentrations.

METHODS

Healthy adult males received centanafadine sustained-release 400 mg/day for 4 days (N = 6) or 800 mg in a single day (N = 4). Assessments included safety monitoring; time course of occupancy of NET, DAT, and SERT; and centanafadine plasma concentrations.

RESULTS

Transporter occupancy was numerically higher for NET versus DAT or SERT. For NET, estimated (mean ± standard error [SE]) maximal observable target occupancy (TO_max) and concentration at half maximal occupancy (IC₅₀) were 64 ± 7% and 132 ± 65 ng/mL, respectively, for all regions and 82 ± 13% and 135 ± 97 ng/mL after excluding the thalamus, which showed high nonspecific binding. For DAT and SERT, TO_max could not be established and was assumed to be 100%; estimated IC₅₀ (mean ± SE) values were 1580 ± 186 ng/mL and 1,760 ± 309 ng/mL, respectively. For centanafadine, the estimated in vivo affinity ratio was 11.9 ± 6.0 (mean ± SE) for NET/DAT, 13.3 ± 7.0 for NET/SERT, and 1.1 ± 0.2 for DAT/SERT. DAT and SERT occupancies at a plasma concentration of 1400 ng/mL were estimated to be 47 and 44%, respectively.

CONCLUSIONS

High occupancy at NET and moderate occupancy at DAT and SERT was observed at peak concentrations achieved following 400 mg total daily doses of centanafadine.

The Potential of N-acetyl Cysteine in Behavioral Addictions and Related Compulsive and Impulsive Behaviors and Disorders: a Scoping Review

Purpose of Review

Behavioral addictions (also termed disorders due to addictive behaviors) contain impulsive and compulsive features and have been shown to involve glutamate dysregulation. N-acetylcysteine (NAC), a well-tolerated cysteine pro-drug and antioxidant, may reduce addictive behaviors by restoring glutamate homeostasis. The current review details and discusses the use of NAC in behavioral addictions and related impulsive and compulsive behaviors, including gambling disorder, problematic use of the internet, problematic video gaming, compulsive sexual behavior, problematic shopping/buying, problematic stealing, repetitive self-injurious behavior, and binge eating disorder.

Recent Findings

Preliminary results have indicated the usefulness of NAC in gambling disorder, self-injurious behaviors, and compulsive sexual behaviors. Preclinical studies indicate that NAC is effective in improving binge eating behavior, but clinical trials are limited to a small open-label trial and case report. Studies are lacking on the efficacy of NAC in problematic use of the internet, problematic video gaming, problematic stealing, and problematic shopping/buying.

Summary

NAC demonstrates potential for use in behavioral addictions and compulsive behaviors, particularly in gambling disorder and self-injury. However, more studies are needed to assess the effectiveness of NAC in other behavioral addictions and the mechanisms by which NAC improves these conditions.

Helpful or Harmful? The Therapeutic Potential of Medications with Varying Degrees of Abuse Liability in the Treatment of Substance Use Disorders

Purpose of Review

This review summarizes recent clinical trial research on pharmacological treatments for substance use disorders, with a specific focus on agents with potential abuse liability.

Recent Findings

Pharmacological treatments for substance use disorders may include gabapentinoids, baclofen, modafinil, ketamine, cannabinoids, gamma-hydroxybutyrate, and psychedelics. Gabapentinoids may decrease negative subjective effects of withdrawal in alcohol and cannabis use disorders. Cannabinoids similarly appear to decrease use and withdrawal symptoms in cannabis use disorder, while research shows stimulant medications may reduce cravings and increase abstinence in cocaine use disorder. Ketamine and psychedelics may help treat multiple substance use disorders. Ketamine may reduce withdrawal symptoms, promote abstinence, and diminish cravings in alcohol and cocaine use disorders and psychedelics may promote remission, decrease use, and reduce cravings in alcohol and opioid use disorders.

Summary

Regardless of current regulatory approval statuses and potentials for abuse, multiple agents should not be dismissed prematurely as possible treatments for substance use disorders. However, further clinical research is needed before effective implementation can begin in practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40429-022-00432-9.

Multimodal neuroimaging of metabotropic glutamate 5 receptors and functional connectivity in alcohol use disorder

BACKGROUND

People recovering from alcohol use disorder (AUD) show altered resting brain connectivity. The metabotropic glutamate 5 (mGlu5) receptor is an important regulator of synaptic plasticity potentially linked with synchronized brain activity and a target of interest in treating AUD. The goal of this work was to assess potential relationships of brain connectivity at rest with mGlu5 receptor availability in people with AUD at two time points early in abstinence.

METHODS

Forty-eight image data sets were acquired with a multimodal neuroimaging battery that included resting-state functional magnetic resonance imaging (fMRI) and mGlu5 receptor positron emission tomography (PET) with the radiotracer [¹⁸ F]FPEB. Participants with AUD (n = 14) were scanned twice, at approximately 1 and 4 weeks after beginning supervised abstinence. [¹⁸ F]FPEB PET results were published previously. Primary comparisons of fMRI outcomes were performed between the AUD group and healthy controls (HCs; n = 23) and assessed changes over time within the AUD group. Relationships between resting-state connectivity measures and mGlu5 receptor availability were explored within groups.

RESULTS

Compared to HCs, global functional connectivity of the orbitofrontal cortex was higher in the AUD group at 4 weeks of abstinence (p = 0.003), while network-level functional connectivity within the default mode network (DMN) was lower (p < 0.04). Exploratory multimodal analyses showed that mGlu5 receptor availability was correlated with global connectivity across all brain regions (HCs, r = 0.41; AUD group at 1 week of abstinence, r = 0.50 and at 4 weeks, r = 0.46; all p < 0.0001). Furthermore, a component of cortical and striatal mGlu5 availability was correlated with connectivity between the DMN and salience networks in HCs (r = 0.60, p = 0.003) but not in the AUD group (p > 0.3).

CONCLUSIONS

These preliminary findings of altered global and network connectivity during the first month of abstinence from drinking may reflect the loss of efficient network function, while exploratory relationships with mGlu5 receptor availability suggest a potential glutamatergic relationship with network coherence.

Lower prefrontal cortical synaptic vesicle binding in cocaine use disorder: An exploratory 11 C-UCB-J positron emission tomography study in humans

Preclinical studies have revealed robust and long-lasting alterations in dendritic spines in the brain following cocaine exposure. Such alterations are hypothesized to underlie enduring maladaptive behaviours observed in cocaine use disorder (CUD). The current study explored whether synaptic density is altered in CUD. Fifteen individuals with DSM-5 CUD and 15 demographically matched healthy control (HC) subjects participated in a single 11 C-UCB-J positron emission tomography scan to assess density of synaptic vesicle glycoprotein 2A (SV2A). The volume of distribution (VT ) and the plasma-free fraction-corrected form of the total volume of distribution (VT /fP ) were analysed in the anterior cingulate cortex (ACC), dorsomedial and ventromedial prefrontal cortex (PFC), lateral and medial orbitofrontal cortex (OFC) and ventral striatum. A significant diagnostic-group-by-region interaction was observed for VT and VT /fP . Post hoc analyses revealed no differences on VT , while for VT /fP showed lower values in CUD as compared with HC subjects in the ACC (-10.9%, p = 0.02), ventromedial PFC (-9.9%, p = 0.02) and medial OFC (-9.9%, p = 0.04). Regional VT /fP values in CUD, though unrelated to measures of lifetime cocaine use, were positively correlated with the frequency of recent cocaine use (p = 0.02-0.03) and negatively correlated with cocaine abstinence (p = 0.008-0.03). These findings provide initial preliminary in vivo evidence of altered (lower) synaptic density in the PFC of humans with CUD. Cross-sectional variation in SV2A availability as a function of recent cocaine use and abstinence suggests that synaptic density may be dynamically and plastically regulated by acute cocaine, an observation that merits direct testing by studies using more definitive longitudinal designs.

The lived experiences of adults with attention-deficit/hyperactivity disorder: A rapid review of qualitative evidence

Attention-deficit/hyperactivity disorder (ADHD) is a common condition that frequently persists into adulthood, although research and diagnostic criteria are focused on how the condition presents in children. We aimed to review qualitative research on lived experiences of adults with ADHD to characterize potential ADHD symptomatology in adulthood and provide perspectives on how needs might be better met. We searched three databases for qualitative studies on ADHD. Studies (n = 35) in English that included data on the lived experiences of adults with ADHD were included. These studies covered experiences of receiving a diagnosis as an adult, symptomatology of adult ADHD, skills used to adapt to these symptoms, relationships between ADHD and substance use, patients' self-perceptions, and participants' experiences interacting with society. Many of the ADHD symptoms reported in these studies had overlap with other psychiatric conditions and may contribute to misdiagnosis and delays in diagnosis. Understanding symptomatology of ADHD in adults may inform future diagnostic criteria and guide interventions to improve quality of life.

First Episode Psychosis and Pituitary Hyperplasia in a Patient With Untreated Hashimoto's Thyroiditis: A Case Report

This case report describes a woman with no psychiatric history and previously diagnosed Hashimoto's thyroiditis who presented to the psychiatric emergency department with a first episode of psychosis. The initial workup for organic causes of psychosis revealed an astronomically high thyroid stimulating hormone (TSH) (> 1,000 μIU/mL) out of proportion to the patient's minimal physical symptoms of hypothyroidism. Additionally the patient's head imaging showed an enlarged pituitary, a rare, but reversible, presentation of chronically untreated primary hypothyroidism. The patient was transferred to a medical unit to receive IV thyroid hormone replacement as well as an adjunctive antipsychotic to assist with remission of her distressing auditory hallucinations and persecutory delusions. This case highlights the importance of a thorough medical workup for causes of new onset psychosis and the need for further consensus in the literature regarding choice of antipsychotic and duration of treatment for psychosis secondary to hypothyroidism.

Imaging brain cortisol regulation in PTSD with a target for 11β-hydroxysteroid dehydrogenase type 1

BACKGROUNDInvestigations of stress dysregulation in posttraumatic stress disorder (PTSD) have focused on peripheral cortisol, but none have examined cortisol in the human brain. This study used positron emission tomography (PET) to image 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), a cortisol-producing enzyme, as a putative brain cortisol marker in PTSD.METHODSSixteen individuals with PTSD and 17 healthy, trauma-exposed controls (TCs) underwent PET imaging with [18F]AS2471907, a radioligand for 11β-HSD1.RESULTSPrefrontal-limbic 11β-HSD1 availability, estimated as [18F]AS2471907 volume of distribution (VT), was significantly higher in the PTSD group compared with the TC group (β = 1.16, P = 0.0057). Lower prefrontal-limbic 11β-HSD1 availability was related to greater overall PTSD severity (R2 = 0.27, P = 0.038) in the PTSD group. 11β-HSD1 availability was not related to plasma cortisol levels (R2 = 0.026, P = 0.37). In a PTSD subset (n = 10), higher 11β-HSD1 availability was associated with higher availability of translocator protein (TSPO), a microglial marker (β = 4.40, P = 0.039).CONCLUSIONHigher brain cortisol-producing 11β-HSD1 in the PTSD group may represent a resilience-promoting neuroadaptation resulting in lower PTSD symptoms. Along with preliminary associations between 11β-HSD1 and TSPO, corroborating previous evidence of immune suppression in PTSD, these findings collectively challenge previous hypotheses of the deleterious effects of both excessive brain glucocorticoid and brain immune signaling in PTSD.FUNDINGBrain and Behavior Research Foundation Independent Investigator Grant, National Institute of Mental Health grants F30MH116607 and R01MH110674, the Veterans Affairs National Center for PTSD, the Gustavus and Louise Pfeiffer Foundation Fellowship, Clinical and Translational Science Awards grant UL1 TR000142 from the NIH National Center for Advancing Translational Science.

Recently abstinent smokers exhibit mood-associated dopamine dysfunction in the ventral striatum compared to nonsmokers: a [11C]-(+)-PHNO PET study

INTRODUCTION

Chronic nicotine exposure desensitizes dopamine responses in animals, but it is not known if this occurs in human tobacco smokers. Deficits in dopamine function are likely to make smoking cessation difficult. We used positron emission tomography (PET) brain imaging with the dopamine D2/3 receptor agonist radioligand [ 11C]-(+)-PHNO to determine if abstinent smokers exhibit less amphetamine-induced dopamine release in the ventral striatum than nonsmokers, and whether this was associated with clinical correlates of smoking cessation.

METHODS

Baseline [ 11C]-(+)-PHNO scans were acquired from smokers (n=22, 7 female, abstinent 11±9 days) and nonsmokers (n=20, 7 female). A subset of thirty-seven participants (18 smokers) received oral amphetamine (0.5 mg/kg) three hours before a second [ 11C]-(+)-PHNO scan. Binding potential (BPND) (i.e., D2/3 receptor availability) was estimated at baseline and post-amphetamine in the ventral striatum. Amphetamine-induced percent change in BPND was calculated to reflect dopamine release. Subjects also completed the Center for Epidemiologic Studies Depression Scale (CES-D).

RESULTS

There were no group differences in baseline BPND. Amphetamine-induced percent change in BPND in the ventral striatum was significantly lower in abstinent smokers compared to nonsmokers (p=0.019; d=0.82). Higher CES-D scores were significantly associated with lower ventral striatal percent change in BPND for abstinent smokers (rs=-0.627, p=0.025).

CONCLUSIONS

In conclusion, abstinent smokers exhibited significantly less amphetamine-induced dopamine release in the ventral striatum than nonsmokers. In abstinent smokers, worse mood was significantly associated with less striatal dopamine release. Our findings highlight a potential neural mechanism that may underlie negative mood symptoms during early abstinence.

IMPLICATIONS

This study combined quantitative PET imaging and an amphetamine challenge to examine striatal dopamine function during early smoking cessation attempts. The findings demonstrate that recently abstinent tobacco smokers exhibit significant, mood-associated striatal dopamine dysfunction compared to nonsmokers. This study advances our knowledge of the neurobiology underlying early quit attempts, and bridges novel neural findings with clinically relevant symptoms of smoking cessation. These results may explain the challenge of maintaining long-term abstinence from smoking, and can lend insight into the development of treatment strategies for smoking cessation.

RETRACTED: Remission of Subacute Psychosis in a COVID-19 Patient With an Antineuronal Autoantibody After Treatment With Intravenous Immunoglobulin

Retraction notice to: “Remission of Subacute Psychosis in a COVID-19 Patient With an Antineuronal Autoantibody After Treatment With Intravenous Immunoglobulin” by Lindsay S. McAlpine, Brooke Lifland, Joseph R. Check, Gustavo A. Angarita, Thomas T. Ngo, Samuel J. Pleasure, Michael R. Wilson, Serena S. Spudich, Shelli F. Farhadian, and Christopher M. Bartley (Biol Psychiatry 2021; 90:e23-e26); https://doi.org/10.1016/j.biopsych.2021.03.033. This article has been retracted at the request of corresponding author Christopher Bartley, with agreement from all authors and with approval from Biological Psychiatry Editor John H. Krystal, M.D. See Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). After this article was published, the authors determined that two cerebrospinal fluid (CSF) samples were inadvertently confused, resulting in publication of the wrong COVID-19 patient’s immunostaining data. The authors determined that the two CSF samples came from COVID-19 patients with sequential case identifiers (i.e., one identifier ended in a “5” and the other in a “6”). To determine whether the published immunostaining results were produced by CSF from another COVID-19 patient, the authors reperformed the mouse brain immunostaining experiments using additional aliquots of stored CSF from the two research participants in question, as well as with the remaining CSF that had been used in the publication. After repeating the immunostaining with these CSF samples, two blinded raters were able to state unequivocally that the CSF samples from the two COVID-19 patients had been confused. Therefore, while the clinical features of the case report are accurate and unaffected, the research data belong to another COVID-19 research participant, not the one described in the published case report. The authors voluntarily informed the Journal of this honest error upon its discovery. All authors agree to retract this paper and sincerely apologize for having allowed the incorrect images to be published with this case report. To avoid misinterpretation of the research findings, both the editors and authors concur that the only proper course of action was to retract this version of the paper. However, this COVID-19 psychosis case remains of clinical interest because of the patient’s clear response to immunotherapy. Therefore, the authors are revising the paper, which the Journal will consider further for publication.

Can pharmacotherapy improve treatment outcomes in people with co-occurring major depressive and cocaine use disorders?

Introduction: Major depressive disorder (MDD) and cocaine use disorder (CUD) are prevalent and frequently co-occur. When co-occurring, the presence of one disorder typically negatively impacts the prognosis for the other. Given the clinical relevance, we sought to examine pharmacotherapies for co-occurring CUD and MDD. While multiple treatment options have been examined in the treatment of each condition individually, studies exploring pharmacological options for their comorbidity are fewer and not conclusive.Areas Covered: For this review, the authors searched the literature in PubMed using clinical query options for therapies and keywords relating to each condition. Then, they described potentially promising pharmacologic therapeutic options based on shared mechanisms between the two conditions and/or results from individual clinical trials conducted to date.Expert opinion: Medications like stimulants, dopamine (D3) receptors partial agonists or antagonists, antagonists of kappa opioid receptors, topiramate, and ketamine could be promising as there is significant overlap relating to reward deficiency models, antireward pathways, and altered glutamatergic systems. However, the available clinical literature on any one of these types of agents is mixed. Additionally, for some agents there is possible concern related to abuse potential (e.g. ketamine and stimulants).

Moderation of Prazosin's Efficacy by Alcohol Withdrawal Symptoms

OBJECTIVE

Alcohol use disorder (AUD) is a leading cause of global disease burden. Chronic, heavy use increases the likelihood of alcohol withdrawal symptoms and associated secondary outcomes of alcohol craving and mood, anxiety, and sleep disturbances, which are predictive of poor treatment outcomes. The authors examined whether alcohol withdrawal symptoms moderate the efficacy of prazosin in reducing alcohol intake and associated secondary outcomes.

METHODS

A 12-week, double-blind, randomized, controlled proof-of-concept trial of prazosin (16 mg/day, with a 2-week titration) was conducted in community-recruited adults with current alcohol dependence (N=100) with varying levels of alcohol withdrawal symptoms assessed at treatment entry. Primary outcomes were daily self-reported drinking days and heavy drinking days, and secondary outcomes were average drinks/day and mood, anxiety, craving, and sleep quality ratings.

RESULTS

Modified intent-to-treat analyses indicated a significant interaction of alcohol withdrawal symptom score by treatment by full-dose treatment period (weeks 3-12) for drinking days, heavy drinking days, and average drinks/day. By week 12, participants with high alcohol withdrawal symptoms on prazosin reported 7.07% heavy drinking days and 27.46% drinking days, while those on placebo had 35.58% heavy drinking days and 58.47% drinking days (heavy drinking days: odds ratio=0.14, 95% CI=0.058, 0.333; drinking days: odds ratio=0.265, 95% CI=0.146, 0.481). No such benefit of prazosin was observed in those reporting low or no alcohol withdrawal symptoms. Individuals with high alcohol withdrawal symptoms on prazosin compared with placebo also showed significantly improved anxiety, depression, and alcohol craving over the course of the trial.

CONCLUSIONS

The findings indicate that alcohol withdrawal symptoms are a significant moderator of prazosin treatment response for alcohol use outcomes and for associated symptoms of alcohol craving, anxiety, and mood symptoms. These data support further evaluation of alcohol withdrawal symptoms as a prognostic indicator of prazosin's efficacy in the treatment of AUD.

Testing the effects of the GLP-1 receptor agonist exenatide on cocaine self-administration and subjective responses in humans with cocaine use disorder

BACKGROUND

Preclinical rodent studies have demonstrated reduced cocaine taking after administration of glucagon-like peptide 1 (GLP-1) analogues. We investigated effects of a GLP-1 analogue (exenatide) on behavioral and subjective effects of cocaine in individuals with cocaine use disorder (CUD).

METHODS

Non-treatment-seeking CUD subjects underwent two human laboratory cocaine self-administration test sessions following an acute 3 -h pre-treatment with exenatide (5 mcg; subcutaneously) or placebo. Primary outcomes consisted of infusions of cocaine and visual analog scale self-ratings of euphoria and wanting cocaine. Secondary outcomes consisted of pertinent hormone levels (GLP-1, insulin, and amylin).

RESULTS

Thirteen individuals completed the study. Acute pretreatment with exenatide versus placebo did not change cocaine infusions (8.5 ± 1.2 vs. 9.1 ± 1.2; p = 0.39), self-reported euphoria (4.4 ± 0.8 vs. 4.1 ± 0.8; p = 0.21), or wanting of cocaine (5.6 ± 0.9 vs. 5.4 ± 0.9; p = 0.46). Exenatide vs. placebo reduced levels of GLP-1 (p = 0.03) and insulin (p = 0.02). Self-administered cocaine also reduced levels of GLP-1 (p < 0.0001), insulin (p < 0.0001), and amylin (p < 0.0001).

CONCLUSIONS

We did not find evidence that low dose exenatide alters cocaine self-administration or the subjective effects of cocaine in people with CUD. Limitations such as single acute rather than chronic pre-treatment, as well as evaluation of only one dose, preclude drawing firm conclusions about the efficacy of exenatide. Exenatide and cocaine independently reduced levels of GLP-1 and insulin, while cocaine also reduced levels of amylin.

Dopamine D2/3 receptor availability in cocaine use disorder individuals with obesity as measured by [11C]PHNO PET

BACKGROUND

Positron emission tomography (PET) work with the dopamine D3 receptor (D₃R) preferring ligand [¹¹C]PHNO in obese individuals has demonstrated higher binding and positive correlations with body mass index (BMI) in otherwise healthy individuals. These findings implicated brain reward areas including the substantia nigra/ventral tegmental area (SN/VTA) and pallidum. In cocaine use disorder (CUD), similar SN/VTA binding profiles have been found compared to healthy control subjects. This study investigates whether BMI-[¹¹C]PHNO relationships are similar in individuals with CUD.

METHODS

Non-obese CUD subjects (N = 12) were compared to age-matched obese CUD subjects (N = 14). All subjects underwent [¹¹C]PHNO acquisition using a High Resolution Research Tomograph PET scanner. Parametric images were computed using the simplified reference tissue model with cerebellum as the reference region. [¹¹C]PHNO measures of receptor availability were calculated and expressed as non-displaceable binding potential (BP_ND).

RESULTS

In between-group analyses, D2/3R availability in non-obese and obese CUD groups was not significantly different overall. BMI was inversely correlated withBP_ND in the SN/VTA (r = -0.45, p = 0.02 uncorrected) in all subjects.

CONCLUSION

These data suggest that obesity in CUD was not associated with significant differences in D_2/3R availability. This in contrast to previous findings in non-CUD individuals that found increased availability of D₃Rs in the SN/VTA associated with obesity. These findings could potentially reflect dysregulation of D₃R in CUD, impacting how affected individuals respond to natural stimuli such as food.

Stress-related suppression of peripheral cytokines predicts future relapse in alcohol-dependent individuals with and without subclinical depression

Chronic alcohol abuse and depressive symptoms are both associated with peripheral cytokine changes. Despite this, cytokine adaptations have not been assessed in co-morbid populations or prospectively as predictors of relapse. We examine cytokine responses to stress in alcohol-dependent individuals and social drinkers, both with and without subclinical depression. We also examine the potential link between cytokine adaptations in response to stress and prospective alcohol relapse risk. Thirty-three, alcohol-dependent individuals (21 with and 12 without high depressive symptoms) and 37 controls (16 with and 21 without high depressive symptoms) were exposed to two 5-minute personalized guided imagery conditions (stress and neutral) across consecutive days in a randomized and counterbalanced order. Alcohol craving and serum measures of tumor necrosis factor alpha (TNFα), tumor necrosis factor receptor 1 (TNFR1), interleukin-6 (IL-6), and interleukin-1 receptor antagonist (IL-1ra) were collected prior to and following imagery exposure. Following treatment discharge, follow-up interviews were conducted over 90 days to assess relapse. Dampened IL-1ra and IL-6 in response to stress was observed as a function of alcohol dependence and not moderated by depressive symptoms. Lower levels of IL-6 following stress also predicted greater drinking days following treatment. Conversely, high depressive symptomatology was associated solely with pro-inflammatory adaptations. Stress-related suppression of TNFα predicted drinking severity only in alcohol-dependent individuals with subclinical depression, and suppressed TNFR1 following stress was only seen in individuals with subclinical depression. Stress-induced suppression of pro-inflammatory TNF markers may indicate a risk factor for alcohol-dependent individuals with co-occurring depressive symptoms.

Effects of Prazosin on Provoked Alcohol Craving and Autonomic and Neuroendocrine Response to Stress in Alcohol Use Disorder

BACKGROUND

Chronic alcohol use results in changes to stress biology and autonomic arousal contributing to acute alcohol withdrawal symptoms, neuroendocrine tolerance of the hypothalamic-pituitary-adrenal axis responses, high stress-induced craving, and risk of alcohol relapse. Thus, stress coping and recovery from alcohol during early abstinence may be jeopardized by such stress system dysfunction. Significant preclinical evidence suggests that noradrenergic disruption may contribute to these alcohol-related stress arousal changes and that alpha-1 adrenergic antagonists, such as prazosin, may normalize these stress system adaptations and reduce alcohol intake. Thus, we hypothesized that prazosin would reduce stress-induced craving and improve neuroendocrine and autonomic response to stress and alcohol cue exposure during early abstinence. We secondarily also assessed the role of lifetime anxiety disorders on these prazosin effects.

METHODS

Forty inpatient treatment-seeking alcohol-dependent individuals were randomly assigned to receive placebo (n = 18) or 16 mg/d, T.I.D., prazosin (n = 22) in a double-blind manner, titrated over 2 weeks. In weeks 3 to 4 after achieving full dose, patients were exposed to 3 5-minute personalized guided imagery conditions (stress cue, alcohol cue, neutral/relaxing cue), on 3 consecutive days in a random, counterbalanced order. Alcohol craving, anxiety, heart rate, cortisol, and adrenocorticotropic hormone (ACTH) levels were assessed at baseline, following imagery and at repeated recovery timepoints.

RESULTS

Prazosin reduced stress cue-induced alcohol craving (p < 0.05) and stress- and alcohol cue-induced anxiety (p < 0.05) and increased heart rate responses in all imagery conditions (p < 0.05). Prazosin lowered basal cortisol and ACTH (p's < 0.05) and attenuated stress cue-induced rises in cortisol (p < 0.05) versus placebo. Finally, in those without lifetime anxiety disorder, the placebo group showed stress- and alcohol cue-induced increases in cortisol (p's < 0.05), while the prazosin group did not.

CONCLUSIONS

Prazosin may attenuate stress cue-induced alcohol craving and anxiety during early abstinence while improving adrenergic and stress system function, effects which are independent of a history of lifetime anxiety disorders.

PTSD is associated with neuroimmune suppression: evidence from PET imaging and postmortem transcriptomic studies

Despite well-known peripheral immune activation in posttraumatic stress disorder (PTSD), there are no studies of brain immunologic regulation in individuals with PTSD. [11C]PBR28 Positron Emission Tomography brain imaging of the 18-kDa translocator protein (TSPO), a microglial biomarker, was conducted in 23 individuals with PTSD and 26 healthy individuals-with or without trauma exposure. Prefrontal-limbic TSPO availability in the PTSD group was negatively associated with PTSD symptom severity and was significantly lower than in controls. Higher C-reactive protein levels were also associated with lower prefrontal-limbic TSPO availability and PTSD severity. An independent postmortem study found no differential gene expression in 22 PTSD vs. 22 controls, but showed lower relative expression of TSPO and microglia-associated genes TNFRSF14 and TSPOAP1 in a female PTSD subgroup. These findings suggest that peripheral immune activation in PTSD is associated with deficient brain microglial activation, challenging prevailing hypotheses positing neuroimmune activation as central to stress-related pathophysiology.

Hypothalamic response to cocaine cues and cocaine addiction severity

The dopaminergic motive system is compromised in cocaine addiction. Abundant research has examined the roles of the dopaminergic midbrain and ventral striatum (VS) in cue-induced craving and habitual drug consumption. Interconnected with the dopaminergic circuits, the hypothalamus is widely implicated in motivated behavior, including food and drug seeking. However, very few studies have investigated how the hypothalamus responds to drug cues and whether hypothalamic responses are related to clinical features such as craving and addiction severity. Here, in 23 cocaine-dependent individuals (CD) exposed to cocaine vs neutral cues during functional magnetic resonance imaging (fMRI), we examined regional responses using established routines. At a corrected threshold, CD demonstrated increased activation to cocaine vs neutral cues in bilateral visual cortex, inferior parietal and middle frontal gyri, and the hypothalamus. The extent of hypothalamus but not other regional response was correlated with craving and cocaine addiction severity, each as assessed by the Cocaine Craving Questionnaire (CCQ) and Cocaine Selective Severity Assessment (CSSA). In contrast, subjective "acute" craving as elicited by cocaine cues during fMRI involved deactivation of bilateral orbitofrontal cortex (OFC) and angular gyri (AG), and the OFC and AG responses were not related to CCQ or CSSA score. These findings distinguished tonic craving as a critical factor in capturing cocaine addiction severity and substantiated a role of the hypothalamus in motivational dysfunction in cocaine addiction.

Lower synaptic density is associated with depression severity and network alterations

Synaptic loss and deficits in functional connectivity are hypothesized to contribute to symptoms associated with major depressive disorder (MDD) and post-traumatic stress disorder (PTSD). The synaptic vesicle glycoprotein 2A (SV2A) can be used to index the number of nerve terminals, an indirect estimate of synaptic density. Here, we used positron emission tomography (PET) with the SV2A radioligand [11C]UCB-J to examine synaptic density in n = 26 unmedicated individuals with MDD, PTSD, or comorbid MDD/PTSD. The severity of depressive symptoms was inversely correlated with SV2A density, and individuals with high levels of depression showing lower SV2A density compared to healthy controls (n = 21). SV2A density was also associated with aberrant network function, as measured by magnetic resonance imaging (MRI) functional connectivity. This is the first in vivo evidence linking lower synaptic density to network alterations and symptoms of depression. Our findings provide further incentive to evaluate interventions that restore synaptic connections to treat depression.

Psychiatric Disorders and Crime in the US Population: Results From the National Epidemiologic Survey on Alcohol and Related Conditions Wave III

OBJECTIVE

Current knowledge regarding the intersection of psychiatric disorders and crime in the United States is limited to psychiatric, forensic, and youth samples. This study presents nationally representative data on the relationship of DSM-5 psychiatric disorders, comorbid substance and mental health disorders, and multimorbidity (number of disorders) with criminal behavior and justice involvement among non-institutionalized US adults.

METHODS

Data were drawn from the National Epidemiologic Survey on Alcohol and Related Conditions Wave III (NESARC-III; 2012-2013; N = 36,309). Logistic regressions were used to examine the association of specific disorders (eg, mood, anxiety, eating, posttraumatic stress, substance use), comorbid substance use and mental health disorders, and multimorbidity with lifetime criminal behavior, incarceration experience, and past-12-month general, alcohol-related, and drug-related legal problems.

RESULTS

Overall, 28.5% of participants reported a history of criminal behavior, 11.4% reported a history of incarceration, 1.8% reported current general legal problems, 0.8% reported current alcohol-related legal problems, and 2.7% reported current drug-related legal problems. The presence of any disorder was associated with a 4 to 5 times increased risk of crime outcomes. Drug use disorders were associated with the highest risk of lifetime crime (adjusted odds ratio [AOR] = 6.8; 95% CI, 6.1-7.6) and incarceration (AOR = 4.7; 95% CI, 4.1-5.3) and current legal problems (AOR = 3.3; 95% CI, 2.6-4.2). Multimorbidity and comorbid substance use and mental health disorders were associated with additional risk. Controlling for antisocial personality disorder did not change the findings.

CONCLUSIONS

Community adults with substance use disorders, comorbid substance use and mental health disorders, and increasing multimorbidity are most at risk of crime and justice involvement, highlighting the importance of community-based addiction treatment.

Severe Illness Anxiety Treated by Integrating Inpatient Psychotherapy With Medical Care and Minimizing Reassurance

Illness anxiety disorder (IAD, formerly hypochondriasis) is characterized by preoccupation with fear of serious illness despite medical reassurance. IAD is common, debilitating, challenging to treat, and results in high healthcare utilization. Outpatient management of IAD is challenging because patients can compulsively seek reassurance from numerous providers, which interferes with learning more productive coping skills. We present the case of a woman with severe IAD who presented to the emergency room with increasing frequency over several months, despite regular outpatient medical visits and escalating psychiatric care. We made the unusual decision to hospitalize her for IAD for 1 month, in the absence of typical hospitalization criteria. This hospitalization allowed us to consolidate all medical and psychiatric care into a single provider team and train all staff and family to communicate with her in a consistent manner. We successfully treated her by integrating a general cognitive-behavioral therapy (CBT) protocol into medical care and decision-making. In response to her numerous health concerns, we minimized medical work-up, reassurance, and reactive medication changes, and instead used the concerns as opportunities to reinforce the psychotherapy. This approach allowed us to simplify her medication regimen and manage her co-morbid hypertension and vitamin deficiencies. Though inpatient hospitalization is likely infeasible in most cases of IAD, outpatient providers may create similar treatment plans based on the example of our case report, without needing highly specialized expertise. Such a plan would require a straightforward understanding of IAD psychology, which we review here, combined with readily accessible tools including a universal CBT protocol, online CBT courses, and clinical symptom scales. We discuss our approach for responding to health concerns, maintaining therapeutic alliance, integrating CBT principles into patient interactions, and managing medications. Since patients with IAD share health concerns with all providers, staff, and family, we also include our own IAD communication guide, appropriate for a general audience, that demonstrates how to respond in these conversations.

Neuroactive steroid levels and cocaine use chronicity in men and women with cocaine use disorder receiving progesterone or placebo

BACKGROUND AND OBJECTIVES

Neuroactive steroids (NAS) may play a role in addiction, with observed increases in response to acute stress and drug use, but decreases with chronic substance use, suggesting that NAS neuroadaptations may occur with chronic substance use. However, levels of NAS in addicted individuals have not been systematically examined. Here, we evaluated a panel of NAS in men and women with cocaine use disorder (CUD) who participated in a clinical laboratory study of progesterone.

METHODS

Forty six CUD individuals were enrolled in a randomized placebo-controlled laboratory study to evaluate progesterone effects on levels of various NAS. On day 5 of a 7-day inpatient treatment regimen of 400 mg/day progesterone (15M/8F) or placebo (14M/9F), plasma levels of NAS known to be downstream of progesterone (allopregnanolone, pregnanolone), and NAS not in the progesterone synthesis pathway (androstanediol, testosterone, dehydroepiandrosterone [DHEA] and the NAS precursor, pregnenolone) were analyzed using highly sensitive gas chromatography/mass spectrometry (GC/MS). The relationship between each of the NAS and chronicity of cocaine use was also assessed.

RESULTS

Progesterone versus placebo significantly increased the GABAergic NAS allopregnanolone and pregnanolone in both CUD men and women. Levels of pregnenolone, testosterone, its GABAergic metabolite androstanediol, and the non-GABAergic DHEA were unaffected by progesterone treatment, and testosterone and androstanediol levels were significantly higher in men than women. Importantly, lower pregnenolone and androstanediol levels were associated with greater years of cocaine use.

SCIENTIFIC SIGNIFICANCE

GABAergic NAS that are upstream from the progesterone synthesis pathway appear susceptible to chronic effects of cocaine use. (Am J Addict 2019;28:16-21).

In vivo imaging of translocator protein, a marker of activated microglia, in alcohol dependence

Neuroinflammation may be a critical component of the neurobiology of alcohol use disorders, yet the exact nature of this relationship is not well understood. This work compared the brain and peripheral immune profile of alcohol-dependent subjects and controls. Brain levels of 18-kDa translocator protein (TSPO), a marker of microglial activation and neuroinflammation, were measured with [¹¹C]PBR28 positron emission tomography imaging in 15 healthy controls and 15 alcohol-dependent subjects. Alcohol-dependent subjects were imaged 1-4 days (n=14) or 24 days (n=1) after their last drink. Linear mixed modeling of partial-volume-corrected [¹¹C]PBR28 data revealed a main effect of alcohol dependence (P=0.034), corresponding to 10% lower TSPO levels in alcohol-dependent subjects. Within this group, exploratory analyses found a negative association of TSPO levels in the hippocampus and striatum with alcohol dependence severity (P<0.035). Peripheral immune response was assessed in a subset of subjects by measuring cytokine expression from monocytes cultured both in the presence and absence of lipopolysaccharide. Peripheral monocyte response to lipopolysaccharide stimulation was lower in alcohol-dependent subjects compared with controls for the proinflammatory cytokines interleukin-6 and interleukin-8. Thus, alcohol-dependent individuals exhibited less activated microglia in the brain and a blunted peripheral proinflammatory response compared with controls. These findings suggest a role for pharmaceuticals tuning the neuroimmune system as therapeutics for alcohol dependence.

Peripheral immune system suppression in early abstinent alcohol-dependent individuals: Links to stress and cue-related craving

BACKGROUND

Peripheral immune system cytokines may play an integral role in the underlying sensitized stress response and alcohol craving during early alcohol withdrawal. To date, the nature of these immune changes during early abstinence have not been examined.

METHODS

A total of 39 early abstinent, treatment-seeking, alcohol-dependent individuals and 46 socially drinking controls were exposed to three guided imageries: stress, alcohol cue and neutral. These were presented randomly across consecutive days. Plasma measures of tumor necrosis factor alpha (TNFα), tumor necrosis factor receptor 1 (TNFR1), interleukin-6 (IL-6), and interleukin-10 (IL-10), were collected at baseline, immediately after imagery and at various recovery time-points. Ratings of alcohol craving, negative mood and anxiety were also obtained at the same time-points.

RESULTS

The alcohol group demonstrated decreased basal IL-10 compared with controls particularly following exposure to alcohol cue. They also showed a dampened TNFα and TNFR1 response to stress and cue, respectively, and a generalized suppression of IL-6. In the alcohol group, these immune system adaptations occurred alongside significant elevations in anxiety, negative mood and alcohol craving.

CONCLUSIONS

Findings demonstrate that broad immunosuppression is still observed in alcohol-dependent individuals after 3 weeks of abstinence and may be linked to motivation for alcohol.

Regional and source-based patterns of [11C]-(+)-PHNO binding potential reveal concurrent alterations in dopamine D2 and D3 receptor availability in cocaine-use disorder

Dopamine type 2 and type 3 receptors (D₂R/D₃R) appear critical to addictive disorders. Cocaine-use disorder (CUD) is associated with lower D₂R availability and greater D₃R availability in regions primarily expressing D₂R or D₃R concentrations, respectively. However, these CUD-related alterations in D₂R and D₃R have not been concurrently detected using available dopaminergic radioligands. Furthermore, receptor availability in regions of mixed D₂R/D₃R concentration in CUD remains unclear. The current study aimed to extend investigations of CUD-related alterations in D₂R and D₃R availability using regional and source-based analyses of [¹¹C]-(+)-PHNO positron emission tomography (PET) of 26 individuals with CUD and 26 matched healthy comparison (HC) participants. Regional analysis detected greater binding potential (BP_ND) in CUD in the midbrain, consistent with prior [¹¹C]-(+)-PHNO research, and lower BP_ND in CUD in the dorsal striatum, consistent with research using non-selective D₂R/D₃R radiotracers. Exploratory independent component analysis (ICA) identified three sources of BP_ND (striatopallidal, pallidonigral, and mesoaccumbens sources) that represent systems of brain regions displaying coherent variation in receptor availability. The striatopallidal source was associated with estimates of regional D₂R-related proportions of BP_ND (calculated using independent reports of [¹¹C]-(+)-PHNO receptor binding fractions), was lower in intensity in CUD and negatively associated with years of cocaine use. By comparison, the pallidonigral source was associated with estimates of regional D₃R distribution, was greater in intensity in CUD and positively associated with years of cocaine use. The current study extends previous D₂R/D₃R research in CUD, demonstrating both lower BP_ND in the D₂R-rich dorsal striatum and greater BP_ND in the D₃R-rich midbrain using a single radiotracer. In addition, exploratory ICA identified sources of [¹¹C]-(+)-PHNO BP_ND that were correlated with regional estimates of D₂R-related and D₃R-related proportions of BP_ND, were consistent with regional differences in CUD, and suggest receptor alterations in CUD may also be present in regions of mixed D₂R/D₃R concentration.

Elevated Dopamine D2/3 Receptor Availability in Obese Individuals: A PET Imaging Study with [11C](+)PHNO

Most prior work with positron emission tomography (PET) dopamine subtype 2/3 receptor (D_2/3R) non-selective antagonist tracers suggests that obese (OB) individuals exhibit lower D_2/3Rs when compared with normal weight (NW) individuals. A D₃-preferring D_2/3R agonist tracer, [¹¹C](+)PHNO, has demonstrated that body mass index (BMI) was positively associated with D_2/3R availability within striatal reward regions. To date, OB individuals have not been studied with [¹¹C](+)PHNO. We assessed D_2/3R availability in striatal and extrastriatal reward regions in 14 OB and 14 age- and gender-matched NW individuals with [¹¹C](+)PHNO PET utilizing a high-resolution research tomograph. Additionally, in regions where group D_2/3R differences were observed, secondary analyses of 42 individuals that constituted an overweight cohort was done to study the linear association between BMI and D_2/3R availability in those respective regions. A group-by-brain region interaction effect (F_{7, 182}=2.08, p=0.047) was observed. Post hoc analyses revealed that OB individuals exhibited higher tracer binding in D₃-rich regions: the substantia nigra/ventral tegmental area (SN/VTA) (+20%; p=0.02), ventral striatum (VST) (+14%; p<0.01), and pallidum (+11%; p=0.02). BMI was also positively associated with D_2/3R availability in the SN/VTA (r=0.34, p=0.03), VST (r=0.36, p=0.02), and pallidum (r=0.30, p=0.05) across all subjects. These data suggest that individuals who are obese have higher D_2/3R availability in brain reward regions densely populated with D₃Rs, potentially identifying a novel pharmacologic target for the treatment of obesity.

Sleep abnormalities associated with alcohol, cannabis, cocaine, and opiate use: a comprehensive review

Sleep abnormalities are associated with acute and chronic use of addictive substances. Although sleep complaints associated with use and abstinence from addictive substances are widely recognized, familiarity with the underlying sleep abnormalities is often lacking, despite evidence that these sleep abnormalities may be recalcitrant and impede good outcomes. Substantial research has now characterized the abnormalities associated with acute and chronic use of alcohol, cannabis, cocaine, and opiates. This review summarizes this research and discusses the clinical implications of sleep abnormalities in the treatment of substance use disorders.

Modafinil and sleep architecture in an inpatient-outpatient treatment study of cocaine dependence

OBJECTIVE

To determine whether the increase in slow-wave sleep associated with modafinil treatment in chronic cocaine users mediates improved clinical outcomes.

METHOD

57 cocaine dependent participants were randomized to receive modafinil 400mg or placebo daily during a period of inpatient treatment followed by six weeks of outpatient treatment. Participants underwent polysomnographic sleep recording during inpatient treatment prior to and after starting modafinil. Outpatient treatment consisted of weekly cognitive behavioral therapy. Contingency management was used to promote participation in treatment and research demands, including thrice weekly visits during the outpatient phase for urine toxicology screens and other assessments. The primary clinical outcome was the percent of urine toxicology screens that were negative for cocaine.

RESULTS

Modafinil treatment was associated with a higher mean percentage (52% vs. 26%) of cocaine-free urine screens (p=0.02) and an increase in N3 sleep time (p=0.002). The change in N3 sleep time mediated the higher rate of cocaine-free urine screens. Modafinil treatment was also associated with more consecutive days abstinent during outpatient treatment, greater survival of abstinence, higher daily rates of abstinence, and less sleep degradation typically associated with abstinence from chronic cocaine use.

CONCLUSIONS

Morning-dosed modafinil improves slow-wave sleep in abstinent cocaine users in the inpatient setting, and this effect is a statistical mediator of improved clinical outcomes associated with continued modafinil treatment. The high rates of abstinence achieved in this trial suggest that promoting healthy sleep physiology in an inpatient setting may be important in the effective treatment of cocaine dependence.

A preliminary study of dopamine D2/3 receptor availability and social status in healthy and cocaine dependent humans imaged with [(11)C](+)PHNO

BACKGROUND

Previous work in healthy non-human primates and humans has shown that social status correlates positively with dopamine 2/3 receptor (D2/3R) availability imaged with antagonist radioligands and positron emission tomography (PET). Further work in non-human primates suggests that this relationship is disrupted by chronic cocaine administration. This exploratory study examined the relationship between social status and D2/3R availability in healthy (HH) and cocaine dependent (CD) humans using the D3-preferring, agonist radioligand, [(11)C](+)PHNO.

METHODS

Sixteen HH and sixteen CD individuals completed the Barratt Simplified Measure of Social Status (BSMSS) and underwent [(11)C](+)PHNO scanning to measure regional brain D2/3R binding potentials (BPND). Correlations between BPND and BSMSS scores were then assessed within each group.

RESULTS

Within HH and CD groups, inverse associations between BSMSS score and BPND were observed in the substantia nigra/ventral tegmental area (SN/VTA) and the ventral striatum, and for the CD group alone, the amygdala. After adjusting for body mass index and age, negative correlations remained significant in the SN/VTA for HH and in the amygdala for CD subjects.

CONCLUSION

These preliminary data utilizing a dopamine agonist tracer demonstrate, for the first time, an inverse association between social status and D2/3R availability in the D3R rich extrastriatal regions of HH and CD humans.

Regulation of cocaine self-administration in humans: lack of evidence for loading and maintenance phases

BACKGROUND

In rodents, cocaine self-administration under a fixed-ratio schedule and with timeout intervals limited to the duration of the infusions is characterized by an initial burst of drug intake (loading) followed by more stable infusion rates (maintenance). We sought to examine whether similar phases might characterize self-regulated cocaine use in humans.

METHODS

31 Non-treatment seeking, cocaine dependent subjects participated in three (8, 16, and 32 mg/70 kg/infusion), self-regulated, 2-h cocaine self-administration sessions under a fixed-ratio 1, 5-min timeout schedule. Data were assessed for visual (e.g., by graphs of cumulative numbers of infusions) and statistical evidence of change in phase (by step-function analyses of individual infusion rates).

RESULTS

Graphs of cumulative infusions over time suggested a single, linear rate of self-administration over 2h at each cocaine dose. Statistical analyses of infusion data by generalized estimating equation (GEE) models also failed to support a loading/maintenance pattern (suggesting, if anything, the possibility of increasing infusion rates over time).

CONCLUSIONS

Our findings fail to support the existence of distinct loading and maintenance phases of self-regulated cocaine administration in humans at behaviorally relevant doses. Several factors may account for these observations including differences between humans and rodents in self-regulated drug intake.

A randomized, double-blind, placebo-controlled trial of long-acting risperidone in cocaine-dependent men

OBJECTIVE

There is no approved pharmaco-therapy for cocaine dependence. Risperidone is an atypical antipsychotic drug with combined dopamine-2/serotonin-2 (D(2)/5-HT(2)) antagonist activity that has been effective in reducing cocaine use in some animal studies. We tested the efficacy of a long-acting, injectable preparation of risperidone on cocaine use in active cocaine users.

METHOD

Thirty-one cocaine-dependent men who met DSM-IV diagnostic criteria for current cocaine dependence entered a 12-week, randomized, double-blind, placebo-controlled trial of intramuscular risperidone, 25 mg every other week. The primary outcome measure was cocaine use as measured by urinary concentration of cocaine metabolites. Secondary outcomes were self-report of cocaine use and craving, depressive symptoms as measured by the Hamilton Rating Scale for Depression (HAM-D), and adverse events. Participants were recruited during a 12-month period from October 2005 to September 2006.

RESULTS

Both groups reduced their cocaine use during the study. There were no between-group differences in the primary measure of cocaine use (urinary metabolites [F = 0.7, p = .41]) or on craving measures. Those assigned to risperi-done reported significantly worsened depressive symptoms (mean +/- SD HAM-D change scores: +7.4 +/- 8.8 vs. -2.3 +/- 5.8, respectively, F = 7.5, p = .018) and gained significantly more weight (mean weight change: +6.3 +/- 9.4 lb vs. -4.0 +/- 8.9 lb, respectively, F = 4.65, p = .044) than those assigned to placebo.

CONCLUSION

Treatment with long-acting injectable risperidone in active cocaine users was not associated with reduction in cocaine use or craving and was associated with worsening of depressive symptoms and weight gain.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00385801.

Prevalence of physical and sexual abuse among substance abuse patients and impact on treatment outcomes

More than half of substance abusers entering addiction treatment report a history of physical or sexual abuse. It is unclear if such a history impacts treatment outcomes. This one-year follow-up study of 700 substance abusers sought to clarify the relationship between lifetime physical and/or sexual abuse and addiction treatment outcome to help address the specific needs of this population. To achieve this goal, baseline characteristics, no-show for treatment status, post-treatment clinical outcomes, and treatment history were studied for subjects with lifetime history of abuse (47.3%) versus without. Abused subjects, predominantly women, were significantly more impaired at baseline on clinical dimensions including family/social severity and psychiatric severity as measured by the Addiction Severity Index (ASI), and general level of functioning. The two groups endorsed different drugs as primary, with the abused group less frequently endorsing heroin and cocaine in favor of alcohol and polydrug use. Abused subjects reported more prior medical and psychiatric treatments. Abuse history was not a predictor of no-show for treatment. Over the 1-year follow-up, lifetime physical and/or sexual abuse was significantly associated with worse psychiatric status and more psychiatric hospitalizations and outpatient treatment despite receiving similar intensive addiction treatment.