Neurobehavioral concomitants of alcohol use in older healthy adults

Sara Jo Nixon^1,2*Samuel A Torres^2,3Jeff Boissoneault^4,5Christian C Garcia⁶Ben Lewis¹

• ¹Departments Psychiatry, Psychology, Neuroscience, University of Florida, Gainesville, United States
• ²UF Center for Addiction Research & Education, Gainesville, FL, United States
• ³Department of Psychiatry, University of Florida, Gainesville, United States
• ⁴Department of Anesthesiology, University of Minnesota Twin Cities, Minneapolis, United States
• ⁵Minnesota Alcohol and Pain Lab, Minneapolis, MN, United States
• ⁶Department of Psychology, University of Cincinnati, Cincinnati, United States

Few laboratory studies permitting granular analyses of alcohol use on neurobehavioral processes in older adults have been reported. This study, reporting baseline data from an on-going longitudinal project, seeks to address this gap. Toward that end, working memory (WM) processes were targeted using the continuous recognition version of the Mnemonic Similarity Task (MST). Healthy male and female drinkers aged 65-80 years completed self-report measures of substance use, negative affect and demographics prior to testing. Drinking patterns were quantified on the basis of typical standard drinks/day (D/D). Behavioral data were obtained in a two-button forced choice paradigm. Neurophysiological data were obtained for each stimulus presentation with analyses focusing on a mid-frontal negative shift occurring ~ 300-500 ms post stimulus (FN400) and a posterior positive shift occurring ~ 550-800 ms after stimulus presentation (LPC). To constrain the models, for the behavioral analyses correlations between D/D, measures of negative affect, stimulus condition (“new”, “identical”, or “similar”) and performance were conducted. They indicated that only accuracy in labeling “new” items was related to D/D. Subsequent least squares regression revealed that D/D was inversely related to accuracy for new items. In a sensitivity analysis removing THC users, the D/D effect was retained. Correlations incorporating mean amplitudes for the FN400 and LPC failed to reveal identifiable patterns. Consequently, separate mixed models (e.g., stimulus condition) for FN400 and LPC were conducted. D/D was not predictive of the FN400 for any stimulus condition. It was negatively related to the LPC mean amplitude. In post-hoc analyses, the effect was most notable for “new” stimuli. After removing THC users, the magnitude and direction of the D/D effect was retained, although the p value fell short of significance. Primary models failed to reveal sex main or interaction effects. However, exploratory post-hoc analyses justify their continued study. These data lend preliminary support for the hypothesis that sustained drinking among older adults may negatively impact neurobehavioral processes. They are also consistent with expectations that alcohol effects may be modest and constrained by specific process. Importantly, these outcomes will be expanded through on-going longitudinal study, extending investigation to study of alcohol-related cognitive decline.