Scalp recorded EEG delta activity during sleep is homeostatically regulated and has important roles in maintaining neurological and physical health. Low levels of delta activity are part of the ubiquitous sleep disturbance in alcoholics. Deficient sleep delta activity has been shown to predict relapse due to the reinforcement of drinking produced by the perceived improvement of sleep following resumption of alcohol consumption. We have previously identified evoked EEG delta frequency responses during sleep as a novel and sensitive state marker of neurophysiologic function in alcoholic men and women. The responses are predominant over frontal brain regions, appear independent of family history of alcohol abuse and are modulated by periods of abstinence. The production of high amplitude EEG responses require the highly synchronized firing of large numbers of healthy neurons, and thus address two aspects of known negative consequences of alcoholism: loss of gray matter and degradation of white matter tracts in the brain. Importantly, there is growing evidence that both gray and white matter may show at least partial recovery with abstinence. This application thus proposes to evaluate the neural mechanisms that are negatively impacted by alcohol abuse, which also show recovery with abstinence and underlie sleep delta activity such as the K- complex (KC). Unique to this application is the combined assessment of high resolution brain structure, microstructural integrity of white matter tracts, and sleep EEG measures of neurophysiology;all using safe and non-invasive techniques. These data will permit an assessment of patterns of degradation and sparing of brain systems following chronic alcohol exposure, and an assessment of structural and functional recovery with abstinence from drinking. The proposal has two major specific aims:
Aim 1 : Determine relative contributions of white matter and gray matter changes to evoked KC amplitude in recently sober alcoholics and matched controls. These data will permit evaluation of the role of white matter microstructural degradation in the reduction in evoked delta EEG amplitude in alcoholics.
Aim 2 : To determine the time course of the abstinence-related recovery in evoked KC amplitude in alcoholics and the role of white matter and gray matter changes in the recovered EEG responses. The hypothesis to be tested is that abstinent alcoholics will show recovery in indices of brain structural and functional integrity over time, while alcoholics who continue to drink or who relapse will show continued decline, and controls will show little or no change. The proposed innovative study will be the first to combine sleep EEG, structural MRI and Diffusion Tensor Imaging to evaluate mechanisms of brain degradation with alcohol abuse;and to track brain recovery with abstinence. The work will help establish metrics of the capacity of brain recovery with abstinence.
Alcoholics who continue to drink sustain ongoing deterioration in central nervous system (CNS) structure and function, including long lasting disruption of sleep. With cessation of drinking, partial recovery of brain function can be attained. This study will assess the brain macrostructural and microstructural underpinnings of a novel index of sleep EEG and its utility as a biological marker of CNS recovery with abstinence from drinking.
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