The eyes have it: Alcohol-induced eye movement impairment and perceived impairment in older adults with and without alcohol use disorder

Background: While alcohol has been shown to impair eye movements in young adults, little is known about alcohol-induced oculomotor impairment in older adults with longer histories of alcohol use. Here, we examined whether older adults with chronic alcohol use disorder (AUD) exhibit more acute tolerance than age-matched light drinkers (LD), evidenced by less alcohol-induced oculomotor impairment and perceived impairment.

Method: Two random-order, double-blinded laboratory sessions with administration of alcohol (0.8 g/kg) or placebo. Participants (n = 117; 55 AUD, 62 LD) were 40-65 years of age. Eye tracking outcomes (pupil size, smooth pursuit gain, pro- and anti-saccadic velocity, latency, and accuracy) were measured at baseline and repeated at peak and declining breath alcohol intervals. Participants rated their perceived impairment during rising and declining intervals.

Results: Following alcohol consumption, older adults with AUD (vs. LD) showed less impairment on smooth pursuit gain and reported lower perceived impairment, but both groups showed similar pupil dilation and impairment on saccadic measures.

Conclusions: While alcohol impaired older adults with AUD less than LD in terms of their ability to track a predictably moving object (i.e., smooth pursuit), both drinking groups were equally sensitive to alcohol-induced delays in reaction time, reductions in velocity, and deficits in accuracy to randomly appearing objects (i.e., saccade tasks). Thus, despite decades of chronic excessive drinking, older adults with AUD exhibited similar oculomotor tolerance on pro- and anti-saccade eye movements relative to their light-drinking counterparts. Given that these individuals also perceived less impairment during intoxication, they may be at risk for injury and harm when they engage in real-life drinking bouts.