Background: Chronic excessive consumption of alcohol produces marked deficits in cognitive and motor abilities, although not all functions are affected to the same extent. Furthermore, although the occurrence of neuropsychological deficits in recently detoxified alcoholics is firmly established, the relative severity of these deficits, the specific neural systems that underlie the deficits, and their relationship to age and alcohol consumption variables either are less established or have proven elusive altogether.

Methods: We administered an extensive battery of neuropsychological tests, chosen for their known sensitivity to brain lesions in specific locations, to 71 recently (1 month) detoxified alcoholic men and 74 healthy controls who spanned the adult age range. Test scores were standardized to the controls for age and grouped a priori into composites that reflected performance in six functional domains: executive functions, short-term memory, upper limb motor ability, declarative memory, visuospatial abilities, and gait and balance. Analogous verbal and nonverbal materials and left- and right-hand upper limb motor tasks were used to test whether alcohol-related deficits were greater for left or right hemisphere.

Results: Compared with controls, the alcoholics were impaired on executive functions, visuospatial abilities, and gait and balance even after we accounted for group differences in estimated premorbid IQ and education. Within the alcoholic group, the most salient deficits were in gait and balance and visuospatial abilities. No consistent lateralized deficit was observed across the four domains tested. Unlike the cognitive composites, the upper limb motor ability and gait and balance composites both showed increasing vulnerability to age, with an independent contribution to the gait and balance dysfunction from the amount of alcohol consumed over a lifetime.

Conclusions: The pattern of functional deficits implicates at least two principal neural systems: the cerebellar-frontal system and the corticocortical system between the prefrontal and parietal cortices. In addition, age and amount of alcohol consumption were better predictors of motor than cognitive impairments.