Neuropathology of Anxiety Disorders Comorbid with Alcohol Dependence

Abstract

Anxiety disorders commonly occur along with other mental or physical illnesses, including alcohol use disorders (AUDs). Like most coexisting disorders, treatment for individuals who suffer from an anxiety disorder and an AUD is particularly challenging, contributing to an increased risk for suicide attempts, more intense withdrawal symptoms, and a higher probability of alcoholism relapse. Previous research has shown that a dysregulation of certain neuronal plasticity-related events in the prefrontal cortex (PFC) is implicated in anxiety disorders and alcohol dependence. However, the exact role this dysregulation plays in the comorbidity of these disorders is not well understood. The experiments conducted here were part of a larger study aimed at understanding the neuropathological characteristics present when anxiety disorders and AUDs coexist. We examined anxiety-like behavior and plasticity-related activity in the brains of rats bred to consume large or small quantities ethanol. After obtaining a prestress baseline of alcohol drinking behavior, rats were exposed to a standard shock procedure in which a mild footshock (paired with a tone) was administered. Drinking activity and anxiety-like behavior were assessed on multiple days following footshock. The rats were then euthanized so that the brains could be examined for activation of plasticity-related activity in the PFC. Significant differences in alcohol consumption and anxiety-like behavior were observed between alcohol-preferring and alcohol-non-preferring rats and are discussed in relation to drinking alcohol as a means to reduce anxiety. These findings will be included in our larger study and will ultimately lead to a better understanding of the neuropathological substrates associated with comorbid anxiety disorders and AUDs.