Research

Yale Specialized Center for Research Excellence (Yale-SCORE).

Funded by ORWH/NIAAA (U54AA027989)

Our Yale-Specialized Center of Research Excellence (SCORE) on sex differences in alcohol use disorder (AUD) brings together a team of leading basic and clinical science experts to pursue an interdisciplinary, translational, cross-species program of research aimed at identifying novel therapeutics to address the recent surge in rates of AUD in women.

Over the past 10 years, rates of AUD in women have increased by 84%, translating to 10.5 million women across the United States. Alcohol use is the 4th leading cause of preventable morbidity and mortality in the United States and women drinkers experience exacerbated health risks associated with alcohol consumption when compared to men. FDA-approved medications were developed primarily or exclusively with samples of men, and none target factors that differentially maintain drinking in women.

A considerable body of data identifies that women are more likely to drink to regulate negative affect and stress, while men are more likely to drink for alcohol-related positive reinforcement. Koob & Volkow have developed a heuristic framework of the addiction cycle, where the ‘withdrawal/negative affect stage’ involves drinking motivated by stress and other negative affect states, also termed ‘the dark side of addiction’. Neuroadaptations during this stage identify reward deficits and stress surfeits, which drive compulsive drinking. Using this negative reinforcement model to guide our research, we target key brain structures, neurochemical systems, HPA-axis activity, neuroimmune function, alcohol metabolism, and sex steroid hormones, which are hypothesized to differentially motivate alcohol consumption in women.

To date, there has not been a concerted effort to incorporate sex as a biological variable (SABV) into AUD medication development. Consequently, the focus of our Yale-SCORE represents a high research priority topic for both NIAAA and ORWH.

Our specific aims and objectives of the Yale-SCORE are to:

• AIM 1: Use a neurobiologically-informed approach focusing on the ‘dark side of addiction’ to inform and expedite the development of sex-appropriate therapeutics targeting stress and negative affect, which differentially maintain drinking in women.
• AIM 2: Mentor SCORE-Early Investigators to become the next generation of biomedical and behavioral researchers focused on alcohol and women’s health spanning the T1 to T4 translational spectrum.
• AIM 3: Be an institutional, regional, and national resource galvanizing the study of sex differences in relation to alcohol use across T1 to T4 translation by providing expert consultation, supporting faculty training awards, leveraging national data on sex and alcohol use to inform treatment and policy, and providing a program of outreach and dissemination.

Project 1: Targeting stress-reactivity and noradrenergic mechanisms for sex-appropriate alcohol use disorder treatment.

PROJECT PI: Sherry McKee PhD

Rates of alcohol use disorders (AUDs) have increased by 84% in women over the past 10 years. Several lines of evidence indicate that drinking behavior in women is more likely to be motivated by affect regulation and stress, whereas drinking in men is motivated by stimulation and alcohol-related positive reinforcement. To date, there has been no concerted effort to develop medications for AUD that target factors which differentially maintain drinking in women. Using Koob & Volkow’s heuristic framework of the addiction cycle162, we will target the ‘dark side of addiction’ for sex-appropriate AUD medication development. Project 1 will focus on a single noradrenergic target, guanfacine, in order to be fully powered to examine sex by medication effects on treatment outcomes. Importantly, Project 1 will provide a template to mechanistically evaluate sex differences in AUD medication development. Our preliminary results demonstrate that guanfacine robustly reduces the quantity, frequency, and percentage of binge episodes of alcohol consumption in both women and men, with possibly larger effects in women. The neural mechanisms underlying this effect appear to be sex-dependent. For women, guanfacine reduces drinking by reducing stress reactivity. For men, the evidence is less clear, but guanfacine appears to target alcohol-related positive reinforcement. Consistent with the aim of the Yale- SCORE to develop sex-appropriate therapeutics for AUD, and with the input and feedback of Project 2 & 3 Leads, we plan to conduct the first, fully-powered, mechanistic Phase 2b, double-blind, placebo-controlled, parallel-group study to examine sex differences in guanfacine's effect on: 1) counteracting stress- and stimulation-based drinking behavior in the laboratory and 2) improving clinical outcomes during a subsequent treatment phase. Importantly, we will examine the safety of guanfacine and potential sex differences in mechanisms underlying drinking (e.g., craving, mood, cognitive function, cardiovascular reactivity, markers of HPA-axis activity, cytokines, markers of alcohol-metabolism, sex steroid hormones, and subjective alcohol effects). Additionally, we will use an innovative biosensor system to assess naturalistic drinking during the 6- week treatment period. To our knowledge, this will be the first clinical trial investigation to prospectively examine sex differences in the therapeutic potential and associated mechanisms of a selective α2a agonist, guanfacine, for the treatment of AUD. Synthesis of findings across the three projects will identify new neurobiological targets for sex-appropriate therapeutics for AUD.

Project 2: Imaging sex differences in stress-related neurochemical mechanisms of alcohol use disorders

PROJECT PI: Kelly Cosgrove PhD

It is increasingly clear that women are more vulnerable than men to some of the negative effects of chronic alcohol consumption, including immune system dysfunction and neurodegeneration. This is important since the rates of problem drinking in women are rapidly increasing, and the currently available treatments are only moderately effective. There is mounting evidence that men and women drink for different reasons. Women tend to drink to regulate stress and negative affect, whereas men report drinking for alcohol-related positive reinforcement. This provides an important opportunity to explore sex-appropriate treatments. In particular, we need to understand the neurochemical mechanisms that underlie and contribute to these behavioral sex differences in order to provide new treatment targets for medication development. In this proposed Yale- SCORE, Project 2 will focus on identifying sex differences in biomarkers of alcohol-induced neurodegeneration that lead to neural adaptations that drive the addiction cycle. Using state-of-the-art positron emission tomography (PET) technology, we will examine sex differences in levels of microglia and synaptic density in living individuals with alcohol use disorder (AUD). Microglia, the brains’ resident immune cells, are involved in a variety of physiologic and pathologic processes, most notably surveying the brains’ environment for danger and carrying out necessary repair functions. Alcohol initially activates microglia but chronic consumption has been shown to suppress both peripheral and neuroimmune systems. We have preliminary data suggesting more severe neuroimmune suppression in women vs. men with AUD, which may underlie the findings that women with AUD exhibit worse mood and neurocognitive dysfunction than men. Microglia are also critical for supporting synaptic structure and function and conversely, microglial dysfunction leads to deficits in synapse number and contributes to mood and cognitive impairment. However, the relationships between microglia, synaptic density, stress, mood, and neurocognitive function in living humans with AUD are not known. In the current study, we will examine whether chronic alcohol consumption is associated with reductions in microglia (Aim 1) and synaptic density (Aim 2) and if the impairment varies by sex. We hypothesize that women with AUD evidence greater deficits in microglia and synaptic density, which underlie sex differences in stress reactivity, negative affect, and neurocognitive dysfunction in AUD (Aim 3). Thus, the proposed project has the potential to measure, for the first time, sex differences in neurochemical markers of neurodegeneration in the living brain of patients with AUD and their relationship to critical clinical outcomes. These findings will advance the alcohol field by uncovering novel, sex-appropriate treatment targets.

Project 3: Neurobiological basis of negative-reinforcement drinking in female and male mice

PROJECT PIs: Marina Picciotto PhD & Yann Mineur PhD

The role of Project 3 is to identify and translate the neurobiological mechanisms underlying the ‘dark side of addiction’ studied across Projects 1 and 2. Women have higher stress reactivity and higher rates of depressive symptoms than men that may underlie their increased likelihood of chronic drinking. Since women are particularly sensitive to effects of stress on negative reinforcement drinking (NRD, see Overall Section), a primary aim of Project 3 is to identify mechanisms related to NRD and related treatments. The amygdala is a sexually-dimorphic structure essential for stress reactivity, and both norepinephrine (NE) and GABA signaling are critical for stress-induced behaviors. Based on the established role of GABA and NE in response to both stress and alcohol use, we hypothesize that the increased susceptibility to chronic alcohol use and relapse in women is partly due to sex differences in GABA-NE balance in subregions of the amygdala. We have shown that guanfacine, a NE agonist at α2A receptors, decreases activity of amygdala neurons and induces anxiolytic and antidepressant-like effects, with sex-dependent patterns of neuronal activation. We therefore hypothesize that targeting pre- and postsynaptic NE receptors or activating GABA neurons will counteract NRD, and could have synergistic effects on amygdala neuronal activity and behaviors induced by stress. We further hypothesize that these neuronal mechanisms interact with neuroinflammatory pathways, such as microglial activation, to modify synaptic structure in the brain area, and that targeting these neuroadaptations could alter NRD in a sex-dependent manner. Finally, we know that alcohol metabolism differs in men and women, and have identified a greater effect of decreased brain metabolism of ethanol in female compared to male mice. In Project 3, we will 1) determine whether targeting noradrenergic receptors decrease overall ethanol intake, as well as NRD in female and male mice, 2) determine whether NE manipulations and GABA neuron activity in the amygdala have synergistic effects on NRD in female and male mice using molecular genetics to target specific GABAergic circuit mechanisms, 3) determine the effects of noradrenergic receptors and GABA neuron activity on ethanol-induced microglia alteration and synaptic density in female and male mice, and 4) identify interactions between brain alcohol metabolism and these signaling pathways in NRD. These studies will provide mechanistic data relevant for studies in Projects 1 and 2 to identify brain mechanisms that may modulate stress-related alcohol use in a sex-dependent manner, and to determine how this contributes to sex differences in alcohol-related behaviors.

Leadership & Administrative Core

CORE PI: Sherry McKee PhD

Career Development Core

CORE PI: Ismene Petrakis MD

Resource Support Core

CORE PI: Ralitza Gueorguieva PhD

Yale-SCOR on Sex Differences in Tobacco Use Disorder (P50DA033945)