Why Harmless Smells Can Affect Some People

For a long time, scientists have believed that those who get ill on account of smells that are harmless to most people are simply faking it, and not necessarily experiencing that many adverse effects. But a new investigation seems to reveal the fact that the very way these persons process smell is different from that most of us do, and that this trait is what makes them feel sick when perceiving a certain, seemingly harmless smell, ScienceDaily reports.

According to Dutch researcher Patricia Bulsing, some people's brains simply process smells faster than the average cortex, and more deeply too. This results in them becoming sick from a smell by simply believing that they could become ill if they made out a certain scent. Bulsing is essentially saying that the people's perception of the smell is the main contributor that brings forth the manifestation of their ailment. In her experiments, the scientist has determined that most individuals who do feel ill when smelling some scents have actually made connections in their brains between the diseases and a smell.

The scientist gives the example of eating something that is bad for you. After the incident, you simply avoid that particular food for a few days or weeks, as seeing it brings about a feeling of being sick, without anything actually being wrong with you. In this example, your brain forms temporary connections linking a certain food to a bad state and triggers that state in the presence of the stimuli. Bulsing set up an experiment in which she taught test subjects to associate a certain smell with pain, by delivering small, electrical shocks to the nose.

The participants were then only subjected to the smell, while the scientist looked at data recorded via electrodes placed on the test subjects' heads. The team working with Bulsing determined that people who had learned to associate pain with smell could pick up, decipher, and process the ominous odor far faster than those in a control group. The new paper was a part of the “Chemosensory irritation from disagreeable and agreeable odours: subjective versus objective effects” project.