Surely you have heard metaphors like “I see everything black” or “the world is gray” to refer to a depressive condition. However, on some occasion you have wondered if this is really the case, if these metaphors have a real origin, if the depressed person perceives the world in a different way.
The depressed person sees the world gray
Well, this question was asked by Ludger Tebartz van Elst, a professor at the University of Freiburg, who has dedicated himself to analyzing the correlation between depression and color vision. Thus, he discovered that, indeed, the depressed person sees the world around him in a different way, compared to those who do not have such a gloomy mood.
But… how did this researcher discover this phenomenon?
He recorded the electrical response of retinal cells (those responsible for “contrast vision”) in healthy people and in depressed people. In practice, he showed each group a board with gray quadrants. The key was that they could manipulate the shades of gray, taking them towards the range of white or black so that the retinal cells were activated more or less in response to these stimuli.
The results showed that in depressed people these cells were activated much less, compared to healthy people. Obviously, this does not mean that people with depression see the world as gray, but it does mean that they see colors with less intensity and brightness, as if they had a glass in front of their eyes that dulls the colors.
Why does this happen?
Researchers think it all depends on dopamine. In fact, retinal cells are normally activated with the release of this neurotransmitter, one of the substances that is most destabilized during a depressive condition.
Depression also affects the sense of smell
Researchers at the University of Dresden went a step further and wondered whether depression could also affect other senses, such as smell. Neither short nor lazy, they recruited 21 people with major depression and 21 healthy subjects.
These researchers placed electrodes on the participants’ skulls while they were given different fragrances to smell. Thus, they discovered that depressed people showed a lesser reaction to aromas; apparently, these were perceived as less intense.
Why?
The researchers analyzed the olfactory bulb (an area of the central nervous system where information coming from the olfactory epithelium is processed and whose function is to detect odors) and discovered that depressed people had a significantly smaller volume than healthy people
They believe that this is because during major depression the neurogenesis process is significantly reduced, which is reflected in the number of mitral cells found in the olfactory bulb.
The good news is that once the person manages to fight depression and eliminate it, they can see colors normally again and recover their sense of smell.
References:
Tebartz van Elst, L. (2010) Seeing gray when feeling blue? Depression can be measured in the eye of the diseased. Biological Psychiatry ; 68(2):205-208.
Negoias, S. (2010) Reduced olfactory bulb volume and olfactory sensitivity in patients with acute major depression. Neuroscience ; 169(1): 415-421.
