Alcohol Improves Your Sense of Smell

How do you smell after a drink? Quite well, it turns out. A modest amount of alcohol boosts your sense of smell.

It is well known that we can improve our sense of smell through practice. But a few people have also experienced a boost after drug use or brain damage. This suggests our sensitivity to smell may be damped by some sort of inhibition in the brain, which can be lifted under some circumstances, says Yaara Endevelt of the Weizmann Institute of Science in Rehovot, Israel.

To explore this notion, Endevelt and her colleagues investigated whether drinking alcohol – known to lower inhibitory signals in the brain – affected the sense of smell.

In one odour-discrimination test, 20 volunteers were asked to smell three different liquids. Two were a mixture of the same six odours, the third contained a similar mixture with one odour replaced. Each volunteer was given 2 seconds to smell each of the liquids and say which was the odd one out. The test was repeated six times with each of three trios of liquids. They were then given a drink that consisted of 35 millilitres of vodka and sweetened grape juice, or the juice alone, before repeating the experiment with the same set of liquids.

One too many

In a second experiment with a similar drinking structure, the same volunteers were asked which of three liquids had a rose-like odour. The researchers increased the concentration of the odour until the volunteers got the right answer three times in a row.

Endevelt's team then tested the senses of people in pubs around the cities of Rehovot and Herzliya. Forty-five volunteers were asked to perform a scratch-and-sniff test, in which they had to identify which one of three odour compounds was different from the other two.

Across all three experiments, the team found a correlation between a person's blood-alcohol level and score on tests of odour detection and discrimination. But while low levels of alcohol improved performance, too much – about two units within an hour for women and three for men – led to a significant reduction in sense of smell.

Endevelt hopes to use brain scans to identify the mechanisms underlying this effect. "If we knew more about the mechanisms that caused this inhibition, then it might shed light on why some people lose their sense of smell and may be helpful for some kinds of olfactory loss," she says.