Anxiety intensifies the sense of smell in people when concerning sniffing out a threat or danger, a study states.
The sense of smell is an essential tool to detect, locate and identify predators in the animal world. The mere presence of predator odours can evoke potent fear and anxiety responses among different species. Smells also evoke powerful emotional responses in humans.
Elizabeth Krusemark and Wen Li from the University of Wisconsin-Madison, hypothesized that in humans, detection of a particular bad smell may signal presence of a noxious airborne substance, or a decaying object that carries disease, the journal Chemosensory Perception reported.
They exposed a group of young adult participants to three types of odours: neutral pure odour, neutral odour mixture, and negative odour mixture. They asked them to detect the presence or absence of an odour in an MRI scanner.
During scanning, the researchers also measured the skin's ability to conduct electricity (a measure of arousal level) and monitored the subjects' breathing patterns, according to a university statement.
They found that as anxiety levels rose, so did the subjects' ability to discriminate negative odours accurately - suggesting a 'remarkable' olfactory acuity to threat in anxious subjects. The skin tests showed that anxiety also heightened emotional arousal to smell-induced threats.
The authors uncovered amplified communication between the sensory and emotional areas of the brain in response to negative odours, particularly in anxiety. This increased connectivity could be responsible for the heightened arousal to threats.
Krusemark and Li concluded: "This enhanced sensory-emotional coupling could serve as a critical mechanism to arouse adequate physiological alertness to potential insults."