Clinical Research Directory

Inflammatory Challenge in Human Aggression.

The goal of this clinical trial is to explore the differences in behavioral and cytokine response to a low dose infusion of endotoxin (vs. placebo) in individuals with histories of frequent, problematic, impulsive aggression ("aggressives") compared to similar individuals without this history ("controls"). Endotoxin is a substance that produces a reliable inflammation response in human subjects. The main questions it aims to answer are: * Do aggressive individuals have greater self-rated anger responses to low-dose endotoxin compared with controls? * Do aggressive individuals have greater analog aggressive responses (in the Taylor Aggression Paradigm) to low-dose endotoxin compared with controls? * Do aggressive individuals have greater hostile attributional and negative emotional responses (in the V-SEIP) to low-dose endotoxin compared with controls? * Do aggressive individuals have greater plasma pro-inflammatory responses to low-dose endotoxin compared with controls? * Do aggressive individuals display a greater activation of brain responses to anger-related picture during an MRI scan during low-dose endotoxin compared with controls? Researchers will compare endotoxin to a placebo (a look-alike substance that contains no drug) explore the differences in behavioral and cytokine response to a low dose infusion of endotoxin (vs. placebo) in individuals with histories of frequent, problematic, impulsive aggression ("aggressives") compared to similar individuals without this history ("controls"). Participants will: * Receive a low-dose of endotoxin and placebo on two (2) separate days. The study drugs will be given through a plastic tube inserted in a forearm vein. * Visit the laboratory on at least two (2) separate days to receive the endotoxin and placebo. * Complete rating forms, behavioral testing, and an MRI on each of the two (2) laboratory days.

Effect of Nitrous Oxide on Aggression.

The goal of this experimental medicine clinical trial is to test the hypothesis that nitrous oxide inhalation will result in a change in neurocircuit function in healthy controls and in individuals with impulsive aggressive tendencies. The main question aims to answer are: Does Nitrous Oxide normalize brain circuit function in impulsively aggressive individuals 24 hours after inhalation. Participants will undergo a 60 minute inhalation session with 50% Nitrous Oxide (or room air at another session) and then undergo an fMRI scan 24 hours later. Researchers will compare healthy controls and impulsively aggressive individuals to see if Nitrous Oxide can normalize the function of cortico-limbic circuits in the latter group.

Pimavanserin and Aggression and Social Cognition.

The investigators are studying how certain drugs can reduce anger outbursts in people with anger problems. In this study the investigators seek to determine if a single 34 mg (two 17 mg tablets) oral dose of the 5-HT2a receptor blocker, pimavanserin, will reduce aggressive responding in individuals with impulsive aggression (Intermittent Explosive Disorder: IED) on a laboratory task that assesses aggression (Taylor Aggression Paradigm: TAP). We will also be examining how this drug impacts hostile social cognition e.g., hostile attribution). If pimvanserin reduces aggression in this study a next step would be a placebo-controlled treatment trial of pimavanserin in study participants with IED. Participation will first involve a remote (e.g., TEAMS) screening session. If potential study participants appear eligible they will come into the lab for an in-person session where participants will complete interviews and questionnaires and have a medical evaluation (including a physical exam, electrocardiogram, and screens for alcohol and drug use). During the next study session, participants will complete a diagnostic interview and a series of questionnaires, all of which can all take place on-line. During the next two sessions (which will be in-person) participants will undergo two (2) study sessions during which study participants will be given a study drug (orally). The drug given, pimavanserin, is currently available and is known to block serotonin receptors thought to be involved in regulating anger. After participants take the study drug, study participants will complete questionnaires and computer tasks for assessment of aggression and of hostile social cognition. Each of these two in-person study sessions will take at least eight (8) hours. A final on-line session will be done to make certain the investigators have all the data required by the study protocol.

Neural Correlates During Alcohol Intoxication

Alcohol intoxication is responsible for a large proportion of violent crime/assault and personal injury in our society. While a number of variables have been associated with alcohol-related aggression, high trait aggression and impaired executive function have been identified as key factors. Both Alcohol Use Disorder (AUD) and Impulsive Aggression behavior (AGG) are related to impaired social-emotional information processing (SEIP) whereby social threat cues, especially ones that are ambiguous in nature, lead to hostile attribution and negative emotional response to the "other" and, then, aggression against the "other". Thus, understanding the underlying neuroscience of SEIP under the influence of alcohol will be critical to identifying targets for intervention to reduce alcohol-related aggressive behavior. In addition to potential pharmacologic and cognitive-behavioral based interventions, such interventions may also involve the rehabilitation of aberrant neuronal circuits underlying social cognitive function through neuroplasticity-based remediation exercises. This study is designed to see how brain activation of cortico-limbic circuits involving social-emotional information processing, analyzed by fMRI Imaging, are impacted by alcohol administration in those with and without aggressive disorders and with and without alcohol use disorder.