Browsing by Author "Smolka, Michael N."

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    Adolescent women induce lower blood alcohol levels than men in a laboratory alcohol self-administration experiment
    (Wiley, 2016-08) Jünger, Elisabeth; Gan, Gabriela; Mick, Inge; Seipt, Christian; Markovic, Alexandra; Sommer, Christian; Plawecki, Martin H.; O'Connor, Sean; Smolka, Michael N.; Zimmermann, Ulrich S.; Psychiatry, School of Medicine
    Background Adolescence is a critical period for the development of alcohol use disorders; drinking habits are rather unstable and genetic influences, such as male sex and a positive Family History of alcoholism (FH), are often masked by environmental factors such as peer pressure. Methods We investigated how sex and FH modulate alcohol use in a sample of 18-19-year-olds from the Dresden Longitudinal Study on Alcohol use in Young Adults (D-LAYA). Adolescents reported their real-life drinking in a TimeLine Follow-Back (TLFB) interview. They subsequently completed a training and an experimental session of free-access intravenous Alcohol Self-Administration (i.v. ASA) using the computer-assisted alcohol infusion system in order to control for environmental cues as well as for biological differences in alcohol pharmacokinetics. During i.v. ASA, we assessed subjective alcohol effects at eight time points. Results Women reported significantly less real-life drinking than men and achieved significantly lower mean arterial Blood Alcohol Concentrations (aBACs) in the laboratory. At the same time, women reported greater sedation relative to men and rated negative effects as high as did men. A positive FH was associated with lower real-life drinking in men but not in women. In the laboratory, FH was not linked to i.v. ASA. Greater real-life drinking was significantly positively associated with higher mean aBACs in the laboratory, and all i.v. ASA indices were highly correlated across the two sessions. Conclusions We conclude that adolescent women chose lower aBACs because they experienced adverse alcohol effects, namely sedation and negative effects, at lower aBACs than men. A positive FH was not apparent as risk factor for drinking in our young sample. The i.v. ASA method demonstrated good external validity as well as test-retest reliability, the latter indicating that a separate training session is not required when employing the i.v. ASA paradigm.
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    Effects of moderate alcohol levels on default mode network connectivity in heavy drinkers
    (Wiley, 2021-05) Fang, Xiaojing; Deza-Araujo, Yacila I.; Petzold, Johannes; Spreer, Maik; Riedel, Philipp; Marxen, Michael; O'Connor, Sean J.; Zimmermann, Ulrich S.; Smolka, Michael N.; Psychiatry, School of Medicine
    Background It is well established that even moderate levels of alcohol affect cognitive functions such as memory, self-related information processing, and response inhibition. Nevertheless, the neural mechanisms underlying these alcohol-induced changes are still unclear, especially on the network level. The default mode network (DMN) plays an important role in memory and self-initiated mental activities; hence, studying functional interactions of the DMN may provide new insights into the neural mechanisms underlying alcohol-related changes. Methods We investigated resting-state functional connectivity (rsFC) of the DMN in a cohort of 37 heavy drinkers at a breath alcohol concentration of 0.8 g/kg. Alcohol and saline were infused in a single-blind crossover design. Results Intranetwork connectivity analyses revealed that participants showed significantly decreased rsFC of the right hippocampus and right middle temporal gyrus during acute alcohol exposure. Moreover, follow-up analyses revealed that these rsFC decreases were more pronounced in participants who reported stronger craving for alcohol. Exploratory internetwork connectivity analyses of the DMN with other resting-state networks showed no significant alcohol-induced changes, but suffered from low statistical power. Conclusions Our results indicate that acute alcohol exposure affects rsFC within the DMN. Functionally, this finding may be associated with impairments in memory encoding and self-referential processes commonly observed during alcohol intoxication. Future resting-state functional magnetic resonance imaging studies might therefore also investigate memory function and test whether DMN-related connectivity changes are associated with alcohol-induced impairments or craving.
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    Epigenome-wide meta-analysis of blood DNA methylation and its association with subcortical volumes: findings from the ENIGMA Epigenetics Working Group
    (Springer Nature, 2021) Jia, Tianye; Chu, Congying; Liu, Yun; Van Dongen, Jenny; Papastergios, Evangelos; Armstrong, Nicola J.; Bastin, Mark E.; Carrillo-Roa, Tania; den Braber, Anouk; Harris, Mathew; Jansen, Rick; Liu, Jingyu; Luciano, Michelle; Ori, Anil P.S.; Santiañez, Roberto Roiz; Ruggeri, Barbara; Sarkisyan, Daniil; Shin, Jean; Sungeun, Kim; Tordesillas Gutiérrez, Diana; van't Ent, Dennis; Ames, David; Artiges, Eric; Bakalkin, Georgy; Banaschewski, Tobias; Bokde, Arun L.W.; Brodaty, Henry; Bromberg, Uli; Brouwer, Rachel; Büchel, Christian; Burke Quinlan, Erin; Cahn, Wiepke; de Zubicaray, Greig I.; Ehrlich, Stefan; Ekström, Tomas J.; Flor, Herta; Fröhner, Juliane H.; Frouin, Vincent; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Hoare, Jacqueline; Ittermann, Bernd; Jahanshad, Neda; Jiang, Jiyang; Kwok, John B.; Martin, Nicholas G.; Martinot, Jean-Luc; Mather, Karen A.; McMahon, Katie L.; McRae, Allan F.; Nees, Frauke; Orfanos, Dimitri Papadopoulos; Paus, Tomáš; Poustka, Luise; Sämann, Philipp G.; Schofield, Peter R.; Smolka, Michael N.; Stein, Dan J.; Strike, Lachlan T.; Teeuw, Jalmar; Thalamuthu, Anbupalam; Trollor, Julian; Walter, Henrik; Wardlaw, Joanna M.; Wen, Wei; Whelan, Robert; Apostolova, Liana G.; Binder, Elisabeth B.; Boomsma, Dorret I.; Calhoun, Vince; Crespo-Facorro, Benedicto; Deary, Ian J.; Hulshoff Pol, Hilleke; Ophoff, Roel A.; Pausova, Zdenka; Sachdev, Perminder S.; Saykin, Andrew; Wright, Margaret J.; Thompson, Paul M.; Schumann, Gunter; Desrivières, Sylvane; Radiology and Imaging Sciences, School of Medicine
    DNA methylation, which is modulated by both genetic factors and environmental exposures, may offer a unique opportunity to discover novel biomarkers of disease-related brain phenotypes, even when measured in other tissues than brain, such as blood. A few studies of small sample sizes have revealed associations between blood DNA methylation and neuropsychopathology, however, large-scale epigenome-wide association studies (EWAS) are needed to investigate the utility of DNA methylation profiling as a peripheral marker for the brain. Here, in an analysis of eleven international cohorts, totalling 3337 individuals, we report epigenome-wide meta-analyses of blood DNA methylation with volumes of the hippocampus, thalamus and nucleus accumbens (NAcc)—three subcortical regions selected for their associations with disease and heritability and volumetric variability. Analyses of individual CpGs revealed genome-wide significant associations with hippocampal volume at two loci. No significant associations were found for analyses of thalamus and nucleus accumbens volumes. Cluster-based analyses revealed additional differentially methylated regions (DMRs) associated with hippocampal volume. DNA methylation at these loci affected expression of proximal genes involved in learning and memory, stem cell maintenance and differentiation, fatty acid metabolism and type-2 diabetes. These DNA methylation marks, their interaction with genetic variants and their impact on gene expression offer new insights into the relationship between epigenetic variation and brain structure and may provide the basis for biomarker discovery in neurodegeneration and neuropsychiatric conditions.
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    Sensation Seeking, Impulsivity, and Aggression Moderate Sex Effects on Adolescent Laboratory Binging
    (APA, 2021-03) Obst, Elisabeth; Bernhardt, Nadine; Gan, Gabriela; Plawecki, Martin H.; O'Connor, Sean; Smolka, Michael N.; Zimmermann, Ulrich S.; Psychiatry, School of Medicine
    Sex, comprising biological and gender-related distinctions, is a known risk factor for alcohol use disorders. Moreover, sensation seeking, impulsivity, and aggression have been found to predict binge drinking and to reflect behavioral disinhibition. We tested effects of these disinhibited traits on binging during intravenous alcohol self-administration (ivASA), a method that eliminates sex differences in the pharmacokinetics of alcohol. Eighty-five German social drinkers (49 men) completed 3 questionnaires assessing sensation seeking, impulsivity, and aggression, as well as an ivASA session at ages 18–19. Sixty-five of them were retested at ages 21–22. Participants reported real-life drinking problems and the number of binge days in the 45 days preceding lab testing. Analyses employed continuous data and median splits to examine associations between disinhibited traits and the portion of women and men in the sample who achieved a breath alcohol concentration of 80 mg% during ivASA (“binge fraction”). At ages 18–19, and only if scoring low on sensation seeking, impulsivity, or aggression, women had significantly lower binge fractions during ivASA than men. Further, low compared to high impulsivity or aggression predicted lower binge fractions in women but not in men. Neither first- nor second-wave disinhibited traits significantly predicted binge fractions at ages 21–22. We perceive that personality traits reflecting behavioral disinhibition might be a strong indicator of drinking problems, specifically among young women. Targeted brief interventions might therefore be used in educational or clinical settings to inform such women about their increased risk and the potential health and behavioral problems associated with binge drinking.
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    Using naltrexone to validate a human laboratory test system to screen new medications for alcoholism (TESMA)- a randomized clinical trial
    (Springer Nature, 2023-04-05) Spreer, Maik; Grählert, Xina; Klut, Ina-Maria; Al Hamdan, Feras; Sommer, Wolfgang H.; Plawecki, Martin H.; O’Connor, Sean; Böttcher, Michael; Sauer, Cathrin; Smolka, Michael N.; Zimmermann, Ulrich S.; Psychiatry, School of Medicine
    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.