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result(s) for
"Zimmermann, Ulrich S."
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A multimodal neuroimaging classifier for alcohol dependence
2020
With progress in magnetic resonance imaging technology and a broader dissemination of state-of-the-art imaging facilities, the acquisition of multiple neuroimaging modalities is becoming increasingly feasible. One particular hope associated with multimodal neuroimaging is the development of reliable data-driven diagnostic classifiers for psychiatric disorders, yet previous studies have often failed to find a benefit of combining multiple modalities. As a psychiatric disorder with established neurobiological effects at several levels of description, alcohol dependence is particularly well-suited for multimodal classification. To this aim, we developed a multimodal classification scheme and applied it to a rich neuroimaging battery (structural, functional task-based and functional resting-state data) collected in a matched sample of alcohol-dependent patients (N = 119) and controls (N = 97). We found that our classification scheme yielded 79.3% diagnostic accuracy, which outperformed the strongest individual modality – grey-matter density – by 2.7%. We found that this moderate benefit of multimodal classification depended on a number of critical design choices: a procedure to select optimal modality-specific classifiers, a fine-grained ensemble prediction based on cross-modal weight matrices and continuous classifier decision values. We conclude that the combination of multiple neuroimaging modalities is able to moderately improve the accuracy of machine-learning-based diagnostic classification in alcohol dependence.
Journal Article
Quantitative neurobiological evidence for accelerated brain aging in alcohol dependence
2017
The premature aging hypothesis of alcohol dependence proposes that the neurobiological and behavioural deficits in individuals with alcohol dependence are analogous to those of chronological aging. However, to date no systematic neurobiological evidence for this hypothesis has been provided. To test the hypothesis, 119 alcohol-dependent subjects and 97 age- and gender-matched healthy control subjects underwent structural MRI. Whole-brain grey matter volume maps were computed from structural MRI scans using voxel-based morphometry and parcelled into a comprehensive set of anatomical brain regions. Regional grey matter volume averages served as the basis for cross-regional similarity analyses and a brain age model. We found a striking correspondence between regional patterns of alcohol- and age-related grey matter loss across 110 brain regions. The brain age model revealed that the brain age of age-matched AD subjects was increased by up to 11.7 years. Interestingly, while no brain aging was detected in the youngest AD subjects (20–30 years), we found that alcohol-related brain aging systematically increased in the following age decades controlling for lifetime alcohol consumption and general health status. Together, these results provide strong evidence for an accelerated aging model of AD and indicate an elevated risk of alcohol-related brain aging in elderly individuals.
Journal Article
Neural and Behavioral Correlates of Alcohol-Induced Aggression Under Provocation
by
Gan, Gabriela
,
Marxen, Michael
,
Zimmermann, Ulrich S
in
Aggression - drug effects
,
Aggression - physiology
,
Aggression - psychology
2015
Although alcohol consumption is linked to increased aggression, its neural correlates have not directly been studied in humans so far. Based on a comprehensive neurobiological model of alcohol-induced aggression, we hypothesized that alcohol-induced aggression would go along with increased amygdala and ventral striatum reactivity and impaired functioning of the prefrontal cortex (PFC) under alcohol. We measured neural and behavioral correlates of alcohol-induced aggression in a provoking vs non-provoking condition with a variant of the Taylor aggression paradigm (TAP) allowing to differentiate between reactive (provoked) and proactive (unprovoked) aggression. In a placebo-controlled cross-over design with moderate alcohol intoxication (~0.6 g/kg), 35 young healthy adults performed the TAP during functional magnetic resonance imaging (fMRI). Analyses revealed that provoking vs non-provoking conditions and alcohol vs placebo increased aggression and decreased brain responses in the anterior cingulate cortex/dorso-medial PFC (provoking
Journal Article
Regaining control over alcohol intake but not abstinence on disulfiram medication, as a harm reduction approach: 2 case reports
by
Vogel-Blaschka, Diana
,
Spreer, Maik
,
Pilhatsch, Maximilian
in
Abstinence
,
Acamprosate
,
Acetaldehyde
2024
Background
Alcohol use disorder (AUD) poses severe health risks, yet many affected individuals opt out of complete abstinence. Therefore, harm reduction strategies have become more prominent in treatment guidelines for AUD. Our two case reports illustrate how disulfiram, initially intended to enforce abstinence, was repurposed to support reduced drinking.
Case Presentations
A 41-year-old patient with a history of severe AUD successfully reduced his alcohol consumption to a low-risk level by leveraging the effects of the disulfiram-alcohol aversive reaction. Another patient, a 63-year-old woman with long histories of AUD and major depressive disorder, experienced fewer depressive episodes and hospitalizations with disulfiram therapy despite periodically intentional discontinuation of medication.
Conclusion
Individualized treatment strategies are critical in optimizing outcomes for patients with AUD. Continuous disulfiram therapy, despite its limitations in directly reducing alcohol intake, might offer a new avenue for harm reduction in exceptional cases even if alcohol consumption continues. The cases suggest that maintaining therapy, aiming at reduced drinking, can enhance the therapeutic alliance and help manage comorbid conditions. Regular medical monitoring is essential for safety and efficacy, warranting further study of possible long-term consequences and psychotropic effects of elevated acetaldehyde levels related to the disulfiram-alcohol interaction.
Journal Article
Association of PER2 Genotype and Stressful Life Events with Alcohol Drinking in Young Adults
by
Banaschewski, Tobias
,
Schmidt, Martin H.
,
Desrivieres, Sylvane
in
Adult
,
Adults
,
Alcohol Drinking - genetics
2013
Clock genes govern circadian rhythms and shape the effect of alcohol use on the physiological system. Exposure to severe negative life events is related to both heavy drinking and disturbed circadian rhythmicity. The aim of this study was 1) to extend previous findings suggesting an association of a haplotype tagging single nucleotide polymorphism of PER2 gene with drinking patterns, and 2) to examine a possible role for an interaction of this gene with life stress in hazardous drinking.
Data were collected as part of an epidemiological cohort study on the outcome of early risk factors followed since birth. At age 19 years, 268 young adults (126 males, 142 females) were genotyped for PER2 rs56013859 and were administered a 45-day alcohol timeline follow-back interview and the Alcohol Use Disorders Identification Test (AUDIT). Life stress was assessed as the number of severe negative life events during the past four years reported in a questionnaire and validated by interview.
Individuals with the minor G allele of rs56013859 were found to be less engaged in alcohol use, drinking at only 72% of the days compared to homozygotes for the major A allele. Moreover, among regular drinkers, a gene x environment interaction emerged (p = .020). While no effects of genotype appeared under conditions of low stress, carriers of the G allele exhibited less hazardous drinking than those homozygous for the A allele when exposed to high stress.
These findings may suggest a role of the circadian rhythm gene PER2 in both the drinking patterns of young adults and in moderating the impact of severe life stress on hazardous drinking in experienced alcohol users. However, in light of the likely burden of multiple tests, the nature of the measures used and the nominal evidence of interaction, replication is needed before drawing firm conclusions.
Journal Article
Acute alcohol intoxication among adolescents—the role of the context of drinking
by
Piontek, Daniela
,
Grüne, Bettina
,
Kraus, Ludwig
in
Acute alcohol intoxication
,
Adolescence
,
Adolescent
2017
This study aims (1) to describe the context of drinking among adolescents with acute alcohol intoxication (AAI) by gender, (2) to explore temporal changes in the context of drinking and (3) to analyse the association between the context of drinking and blood alcohol concentration (BAC). A retrospective chart review of 12- to 17-year-old inpatients with AAI (
n
= 1441) of the years 2000 to 2006 has been conducted in five participating hospitals in Germany. Gender differences in the context of drinking were tested with
t
test and chi
2
test. Differences over time were analysed using logistic regressions. Multivariate linear regression was used to predict BAC. Girls and boys differed in admission time, drinking situation, drinking occasion and admission context. No temporal changes in drinking situation and in admission to hospital from public locations or places were found. Higher BAC coincided with male gender and age. Moreover, BAC was higher among patients admitted to hospital from public places and lower among patients who drank for coping.
Conclusion
: The results suggest gender differences in the context of drinking. The context of drinking needs to be considered in the development and implementation of target group-specific prevention and intervention measures.
What is known:
• The context of drinking, e.g
.
when, where, why and with whom is associated with episodic heavy drinking among adolescents.
What is new:
• Male and female inpatients with acute alcohol intoxication differ with regards to the context of drinking, i.e. in admission time, drinking situation, drinking occasion and admission context.
• Being admitted to hospital from public places is associated with higher blood alcohol concentration.
Journal Article
Using naltrexone to validate a human laboratory test system to screen new medications for alcoholism (TESMA)- a randomized clinical trial
by
Spreer, Maik
,
Grählert, Xina
,
Zimmermann, Ulrich S
in
Alcoholism
,
Clinical trials
,
Laboratories
2023
This registered clinical trial sought to validate a laboratory test system devised to screen medications for alcoholism treatment (TESMA) under different contingencies of alcohol reinforcement. Forty-six nondependent, but at least medium-risk drinkers were given the opportunity to earn intravenous infusions of ethanol, or saline, as rewards for work in a progressive-ratio paradigm. Work demand pattern and alcohol exposure dynamics were devised to achieve a gradual shift from low-demand work for alcohol (WFA) permitting quickly increasing breath alcohol concentrations (BrAC) to high-demand WFA, which could only decelerate an inevitable decrease of the previously earned BrAC. Thereby, the reward contingency changed, modeling different drinking motivations. The experiment was repeated after at least 7 days of randomized, double-blinded treatment with naltrexone, escalated to 50 mg/d, or placebo. Subjects treated with naltrexone reduced their cumulative WFA (cWFA) slightly more than participants receiving placebo. This difference was not statistically significant in the preplanned analysis of the entire 150 min of self-administration, i.e., our primary endpoint (p = 0.471, Cohen’s d = 0.215). Naltrexone serum levels correlated with change in cWFA (r = −0.53; p = 0.014). Separate exploratory analyses revealed that naltrexone significantly reduced WFA during the first, but not the second half of the experiment (Cohen’s d = 0.643 and 0.14, respectively). Phase-dependent associations of WFA with changes in subjective stimulation, wellbeing and desire for alcohol suggested that the predominant reinforcement of WFA was positive during the first phase only, and might have been negative during the second. We conclude that the TESMA is a safe and practical method. It bears the potential to quickly and efficiently screen new drugs for their efficacy to attenuate positively reinforced alcohol consumption. It possibly also provides a condition of negative reinforcement, and for the first time provides experimental evidence suggesting that naltrexone’s effect might depend on reward contingency.
Journal Article
How Accumulated Real Life Stress Experience and Cognitive Speed Interact on Decision-Making Processes
2017
Advances in neurocomputational modeling suggest that valuation systems for goal-directed (deliberative) on one side, and habitual (automatic) decision-making on the other side may rely on distinct computational strategies for reinforcement learning, namely model-free vs. model-based learning. As a key theoretical difference, the model-based system strongly demands cognitive functions to plan actions prospectively based on an internal cognitive model of the environment, whereas valuation in the model-free system relies on rather simple learning rules from operant conditioning to retrospectively associate actions with their outcomes and is thus cognitively less demanding. Acute stress reactivity is known to impair model-based but not model-free choice behavior, with higher working memory capacity protecting the model-based system from acute stress. However, it is not clear which impact accumulated real life stress has on model-free and model-based decision systems and how this influence interacts with cognitive abilities.
We used a sequential decision-making task distinguishing relative contributions of both learning strategies to choice behavior, the Social Readjustment Rating Scale questionnaire to assess accumulated real life stress, and the Digit Symbol Substitution Test to test cognitive speed in 95 healthy subjects.
Individuals reporting high stress exposure who had low cognitive speed showed reduced model-based but increased model-free behavioral control. In contrast, subjects exposed to accumulated real life stress with high cognitive speed displayed increased model-based performance but reduced model-free control.
These findings suggest that accumulated real life stress exposure can enhance reliance on cognitive speed for model-based computations, which may ultimately protect the model-based system from the detrimental influences of accumulated real life stress. The combination of accumulated real life stress exposure and slower information processing capacities, however, might favor model-free strategies. Thus, the valence and preference of either system strongly depends on stressful experiences and individual cognitive capacities.
Journal Article
Targeted intervention: Computational approaches to elucidate and predict relapse in alcoholism
by
Smolka, Michael N.
,
Schlagenhauf, Florian
,
Deserno, Lorenz
in
Addictions
,
Addictive behaviors
,
Alcohol use
2017
Alcohol use disorder (AUD) and addiction in general is characterized by failures of choice resulting in repeated drug intake despite severe negative consequences. Behavioral change is hard to accomplish and relapse after detoxification is common and can be promoted by consumption of small amounts of alcohol as well as exposure to alcohol-associated cues or stress. While those environmental factors contributing to relapse have long been identified, the underlying psychological and neurobiological mechanism on which those factors act are to date incompletely understood. Based on the reinforcing effects of drugs of abuse, animal experiments showed that drug, cue and stress exposure affect Pavlovian and instrumental learning processes, which can increase salience of drug cues and promote habitual drug intake. In humans, computational approaches can help to quantify changes in key learning mechanisms during the development and maintenance of alcohol dependence, e.g. by using sequential decision making in combination with computational modeling to elucidate individual differences in model-free versus more complex, model-based learning strategies and their neurobiological correlates such as prediction error signaling in fronto-striatal circuits. Computational models can also help to explain how alcohol-associated cues trigger relapse: mechanisms such as Pavlovian-to-Instrumental Transfer can quantify to which degree Pavlovian conditioned stimuli can facilitate approach behavior including alcohol seeking and intake. By using generative models of behavioral and neural data, computational approaches can help to quantify individual differences in psychophysiological mechanisms that underlie the development and maintenance of AUD and thus promote targeted intervention.
•Relapse after detoxification is of pivotal clinical importance in alcohol use disorders•Relapse after detoxification is promoted by exposure to alcohol, to alcohol-associated cues and to stress•Reduced goal-directed behavioral and enhanced influence of Pavlovian drugassociated cues on behavior contribute to relapse•Combining refined imaging paradigms with computational approaches might help characterizing the underlying neurophysiology
Journal Article
Dissociating neural learning signals in human sign- and goal-trackers
by
Friedel, Eva
,
Garbusow, Maria
,
Sommer, Christian
in
631/378/116/2396
,
631/378/1595/1395
,
631/378/1788
2020
Individuals differ in how they learn from experience. In Pavlovian conditioning models, where cues predict reinforcer delivery at a different goal location, some animals—called sign-trackers—come to approach the cue, whereas others, called goal-trackers, approach the goal. In sign-trackers, model-free phasic dopaminergic reward-prediction errors underlie learning, which renders stimuli ‘wanted’. Goal-trackers do not rely on dopamine for learning and are thought to use model-based learning. We demonstrate this double dissociation in 129 male humans using eye-tracking, pupillometry and functional magnetic resonance imaging informed by computational models of sign- and goal-tracking. We show that sign-trackers exhibit a neural reward prediction error signal that is not detectable in goal-trackers. Model-free value only guides gaze and pupil dilation in sign-trackers. Goal-trackers instead exhibit a stronger model-based neural state prediction error signal. This model-based construct determines gaze and pupil dilation more in goal-trackers.
Schad et al. find that, during Pavlovian conditioning, model-free striatal reward prediction errors are present in a group of sign-tracking humans, while goal-tracking humans show learning signals from a model-based system instead.
Journal Article
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