May psychotropic drugs cause body odor

Relationship between mental illness and the sense of smell?

It is not very common for test subjects to get tears in their eyes during a scientific experiment. In the tests that took place in 2014 at the Technical University of Dresden, however, exactly this reaction was expected: The scientists asked themselves how mood affects olfactory ability. To this end, they showed their participants - 24 women and 7 men - the final scene from the film "The Champ". In it, a little boy cries for his dying father, who was critically injured in a boxing match. The heart-wrenching neckline is very reliable when it comes to constricting the audience. The film owes a steep career in research to this fact: psychologists and medical professionals have been using it regularly since the 1990s to study sad states of mind.

So now the odor researchers Elena Flohr, Elena Erwin, Ilona Croy and Thomas Hummel. They wanted to find out if dejection hits the nose. In fact, the results of the Dresden team suggest: After the film was shown, they let their bent test subjects sniff the stink of rotten eggs. The participants processed the stimulus more slowly than normal, as measurements by electroencephalography (EEG) showed. In addition, the peak in the brain waveform that was observed shortly after the onset of the stench was slightly lower in the sad state.

This article is included in Spectrum - The Week, 27/2019

The differences were not great. However, they fit into the picture: The Düsseldorf psychologist Bettina Pause was able to determine similar changes in the EEG in depressed patients as early as 2003. After successful drug treatment, these abnormalities disappeared again. Pause was also one of the first to show that depressed people only perceive smells at higher intensities than healthy people and that smelling increases again after therapy. Apparently there is a clear connection between illness, odor perception and processing.

Does a lack of smell make you depressed?

And this does not only apply to depression: there is now increasing evidence that many psychological and neurodegenerative disorders - whether schizophrenia, autism or Alzheimer's dementia - can be recognized by the sense of smell. Scientists around the world are searching for the causes of this connection. In the case of the Depression, for example, they have put together a whole series of pieces of the mosaic in recent years. But the picture they give is by no means complete. This is especially true for the question of causality: Does a lack of smell make you depressed? Or is it the other way around?

The Dresden work rather suggests the second explanation. A result of Bettina Pause's group also fits in with this: the scientists set test subjects a task that could only seemingly be solved and then gave them negative feedback. So the participants felt like they were doing badly, no matter how hard they tried. As a result, they felt helpless - an emotion that is also characteristic of depression.

"During such an experience of helplessness, the same thing obviously happens in the brain of those affected as in depressive patients: Their early olfactory stimulus processing is restricted" (Bettina Pause)

At the same time, their odor processing changed: Compared to a control group, olfactory stimuli led to a significantly weaker rash in the brain waveform, very similar to the experiment at the TU Dresden. "During such an experience of helplessness, the same thing obviously happens in the brain of those affected as in depressed patients," says the Düsseldorf psychologist: "Your early olfactory processing of stimuli is restricted."