1. fMRI Studies of Motivation a. Dopamine Transporter Methylation and Reward Anticipation. In collaboration with Dr. Falk Lohoffs Section on Clinical Genomics and Experimental Therapeutics (CGET), and Dr. Nora Volkows Laboratotry of Neuroimaging (LNI), we analyzed Monetary Incentive Delay (MID) task data to investigate if there was an effect of SLC6A3 methylation on reward processing. We found that percent methylation of SLC6A3 significantly predicted reward anticipation-related activity in the caudate and nucleus accumbens in alcohol dependent patients but not in healthy control individuals. Higher methylation may result in lower DAT transcription and expression in the striatum, which may in turn compromise dopamine reuptake. Compromised dopamine reuptake may impair decision-making associated with excess drug seeking. We have submitted a manuscript: Dopamine Transporter Gene Methylation is Associated with Nucleus Accumbens Activation during Reward Processing in Healthy but not Alcohol-Dependent Individuals, to the journal of Addiction Biology that is under review. We are currently working on the potential effects this factor may have on the on the neural substrates of viewing emotional faces. b. MID Task for Neuroimaging Omega-3 and Reward in Adults with ADHD (NORAA) trial Study. A modified version of the MID task was used in a collaboration with Dr. Hibbeln of the Section on Nutritional Neuroscience. In this study, the effect of Omega-3 supplementation on reward circuitry was investigated in a population of adults with ADHD. CNIRC has assisted in the design and conducted the analysis of this component of the study. Potential differences in reward processing in individuals with ADHD has been observed. Detailed analysis of the data and preparation of the manuscript are underway. c. Reward Incentive Delay (RID) Task for Ghrelin Study. We analyzed the data from a study conducted by Dr. Leggios Section on Clinical Psychoneuroendocrinology and Neuropsychopharma-cology (CPN). This study used the RIDfb task, a modification of the MID task that uses food and beverage images as cues, to investigate the role of ghrelin, a neuropeptide involved in regulating hunger and reward perception, in alcohol craving and use in a population of non-treatment seeking heavy drinkers. In this task, the neural regions associated with motivation and response to reward were assessed as the participants attempted to earn points for intravenous alcohol and food rewards. Results showed that ghrelin increased the alcohol-cue signal in the amygdala and modulated the food-cue signal in the medial orbitofrontal cortex and nucleus accumbens. We also found increased resting-state connectivity between right amygdala and right mOFC prior to alcohol infusion and decrease connectivity after the alcohol infusion. The relationship between breath alcohol concentration and subjective effects of alcohol was also moderated by ghrelin. These data indicate that ghrelin signaling affects alcohol seeking in humans and should be further investigated as a promising target for developing novel medications for alcohol use disorder. The manuscript for this study: Exogenous Ghrelin Administration Increases Alcohol Self-Administration and Modulates Brain Functional Activity in Heavy-Drinking Alcohol-Dependent Individuals has been accepted for publication in Molecular Psychiatry. d. Reward Incentive Delay with Shock (RIDs) Task. We have continued conducting a novel translational study to explore the neural correlates of aversion resistant alcohol addiction using a paradigm, which adds an aversive component to the RID task. In this study, the participants (light and heavy drinkers) are able to earn points for real alcohol and food rewards at the risk of receiving a small electric shock. The behavioral results indicate a difference between light and heavy drinkers for high threat alcohol. Heavy drinkers are more willing to risk receiving an electric shock in order to win alcohol points, indicated by a greater number of button presses during high threat alcohol trials. Our neuroimaging results indicate that heavy drinkers have increased amygdala activation when participants see an alcohol cue in the high threat condition compared to light drinkers. Heavy drinkers show increased BOLD activation in the striatum and insula during alcohol miss feedback compared to light drinkers. This increase in activation may represent a prediction error signal, which is higher in the heavy drinkers due to the increased salience of the alcohol reward to this group. We are currently enrolling the last few subjects needed to complete this study. 2. fMRI Studies of Decision-Making Ultimatum Task. We have conducted a study utilizing a modified version of the Ultimatum Game, a paradigm where participants are given an offer which divides $20.00 between the participant and the proposer. Participants were given the option to accept or reject each offer. Previous studies have demonstrated that the insula plays a key role in processing perceived unfair offers. Our fMRI results indicate higher activation in the healthy controls (HCs) compared to alcohol dependent inviduals in the insular cortex to unfair offers (less than $15:$5 split) that were later rejected. HCs insula activation may have acted as a mediator between emotional responses versus the risk of rejecting such offers. The manuscript for this study is under review. 3. fMRI Studies of Stress In a collaborative study with Dr. Lohoffs CGET we have implemented an fMRI fear extinction task. The primary goal of this study is to evaluate the role and interaction of (epi)genetic factors, early life stress (ELS) exposure, and alcohol use disorder (AUD) on neuronal mechanisms of fear conditioning and extinction. We have completed the preliminary analysis of the imaging data for 54 participants. Having found some trend level hypothesized neural responses, it has been decided that the study will continue collecting data to increase the statistical power of analyses. 4. Experimental fMRI Studies and Treatments a. GSK Study. We provided the imaging expertise for an experimental treatment study investigating verucerfont (CRF receptor antagonist) as a potential treatment for participants with alcohol use disorders (Schwandt, Cortes et al. 2016). The imaging results not only showed significant effects of the verucerfont, but also suggested that the CRF receptor antagonist may have a the motivational effect on alcohol cue reactivity. We tested this hypothesis by conducting an analysis of functional connectivity. We have presented the results of this analysis at the 2017 RSA meeting. We found that compared to placebo group, the verucerfont group showed reduction of the connectivity of the bilateral CeM with regions of the mPFC, dorsolateral PFC, IFG, and anterior insula when viewing alcohol vs. non-alcohol pictures. Additionally, the Verucerfont group showed a trend towards a positive correlation between the task-driven connectivity of the left CeMA with the bilateral superior frontal gyri/SMA and the area under the curve of the AUQ scores during the neutral script. These findings may provide insight into the lack of behavioral difference between the two groups in reducing the alcohol craving by verucerfont. b. BMS Trier Data Analysis. We have further analyzed the imaging data of the Trier test, a stress inducing procedure, collected during a previous study of Pexacerfont (Kwako et al. 2015). Our preliminary analyses indicate increased activation in the anterior cingulate and inferior frontal gyri in alcohol dependent patients when listening to self-referential stress scripts compared to non-self stress scripts. These differences were reduced in individuals who were treated with Pexacerfont but did not reachstatistical significance. The data is still under analysis.
| Vatsalya, Vatsalya; Gowin, Joshua L; Schwandt, Melanie L et al. (2015) Effects of Varenicline on Neural Correlates of Alcohol Salience in Heavy Drinkers. Int J Neuropsychopharmacol 18: |
| Gilman, Jodi M; Smith, Ashley R; Bjork, James M et al. (2015) Cumulative gains enhance striatal response to reward opportunities in alcohol-dependent patients. Addict Biol 20:580-93 |
| Kwako, Laura E; Spagnolo, Primavera A; Schwandt, Melanie L et al. (2015) The corticotropin releasing hormone-1 (CRH1) receptor antagonist pexacerfont in alcohol dependence: a randomized controlled experimental medicine study. Neuropsychopharmacology 40:1053-63 |
| Suchankova, P; Yan, J; Schwandt, M L et al. (2015) The glucagon-like peptide-1 receptor as a potential treatment target in alcohol use disorder: evidence from human genetic association studies and a mouse model of alcohol dependence. Transl Psychiatry 5:e583 |
