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Disinhibition of olfaction: Human olfactory performance improves following low levels of alcohol

Recent research suggests that a modest amount of alcohol boosts your sense of smell. It is hypothesised that true human olfactory abilities are obscured by cortical inhibition. Alcohol reduces inhibition. Researchers therefore tested the hypothesis that olfactory abilities will improve following alcohol consumption.

Olfaction was measured in 85 subjects, 45 in a betweensubjects design, and 40 in a repeated-measures within-subjects design before and after consumption of alcoholic or non-alcoholic beverages. Subjects were also assessed using neurocognitive measures of inhibition. Following alcohol consumption, blood alcohol levels ranged from 0.005% to 0.11%. Across subjects, before any consumption of alcohol, it was found that individuals who were less inhibited had lower (better) olfactory detection thresholds (r = 0.68, p < 0.005). Moreover, after alcohol consumption, subjects with low alcohol levels could make olfactory discriminations that subjects with 0% alcohol could not make (chance = 33%, alcohol = 51.3 ± 22.7%, control = 34.7 ± 31.6%, t(43) = 2.03, p < 0.05). Within subjects, it was found correlations between levels of alcohol and olfactory detection (r = 0.63, p < 0.005) and discrimination (r = _0.50, p < 0.05), such that performance was improved at low levels of alcohol (significantly better than baseline for detection) and deteriorated at higher levels of alcohol. Finally, levels of alcohol-induced improved olfactory discrimination were correlated with levels of alcohol-induced cognitive disinhibition (r = 0.48, p < 0.05).

The authors state that although they cannot rule out alternative non-inhibitory alcohol-induced routes of influence, they conclude that improved olfaction at low levels of alcohol supports the notion of an inhibitory mechanism obscuring true olfactory abilities. Source: Disinhibition of olfaction: Human olfactory performance improves following low levels of alcohol. Endevelt-Shapira Y, Shushan S, Roth Y, Sobel N. Behav Brain Res. 2014 Oct 1;272:66-74. doi: 10.1016/j.bbr.2014.06.024. Epub 2014 Jun 25.

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