Researchers recently investigated the effects of alcohol consumption on eye movement and perceived impairment in older adults with and without alcohol use disorder. They aimed to determine whether participants with chronic excessive alcohol use exhibited behavioral tolerance to alcohol-induced eye movement impairment compared with light drinkers.
The researchers employed a double-blind, randomized, placebo-controlled design and enrolled 117 participants aged 40 to 65 years (55 with alcohol use disorder [AUD] and 62 light drinkers [LD]). Participants attended two laboratory sessions, where they received either an alcohol dose of 0.8 g/kg or placebo. Eye tracking assessments, including smooth pursuit, prosaccade, and antisaccade tasks, were performed prior to and following alcohol consumption. Participants rated their perceived impairment at multiple time points.
According to their findings, published in Alcohol: Clinical & Experimental Research, alcohol impaired smooth pursuit performance in both groups, but those with AUD exhibited significantly less impairment than LDs. This may be because of the underlying neurobiology of these eye movements, posited the researchers, led by Nathan Didier, of the Department of Psychiatry & Behavioral Neuroscience at the University of Chicago. Plasticity of the visual cortex could suggest that “smooth pursuit neurobiology may gradually adapt to alcohol over decades of drinking. This might explain why differential smooth pursuit tolerance was observed in older adults but not in young adults with shorter drinking histories,” they added.
However, both groups showed similar deficits in prosaccade and antisaccade accuracy, latency, and velocity. The AUD group reported lower perceived impairment after alcohol consumption than the LD group, despite experiencing objective deficits in eye movement performance.
Alcohol-induced pupil dilation was comparable between the two groups. This finding indicated similar physiologic responses to alcohol in terms of pupillary function.
“[Patients] with AUD may believe they can ‘hold their liquor’ and perform well when inebriated,” the study authors wrote, “but this perception is incongruous with objective measures showing that they are susceptible to oculomotor impairment. Such overconfidence may underlie the high rates of alcohol-associated injury and harm observed in excessive drinkers.” They noted that almost half of patients treated for traumatic brain injury meet the criteria for AUD “and fatal vehicle injuries are more than 10 times as likely during binge episodes.”
Study limitations included constraints on analyses of oculomotor impairment because of the fixed doses administered during one alcohol and one placebo lab session. Premorbid observed group differences could not be ruled out because of the lack of longitudinal design, and the perceived impairment scale did not ask participants specifically about perceptions of visual acuity or eye movements.
“Older adults with chronic AUD are likely prone to injury when they engage in real-life drinking bouts, as their ability to detect and respond to unexpected objects is hindered during intoxication,” the study authors concluded.
No conflicts of interest were declared.
