Turns out when we’re depressed, we really do see the world differently

It’s often said that when we’re depressed we see the world differently, but most of the time that’s meant in a figurative sense. Now, a new study finds depression literally changes how we view the world.

Researchers from the University of Helsinki in Finland have collected compelling evidence showing that the brain processes visual information differently when an individual is depressed. More specifically, these visual discrepancies likely originate in the cerebral cortex.

It’s no secret that mood impacts perception. When we’re having a bad day, everything seems just a little worse off. Depression is especially notorious for this effect. While feeling positive and upbeat, most people can find something to smile about on a grey and cloudy day, but during a particularly intense bout of depression, the most beautiful scenes and landscapes on the planet aren’t enough to crack a smile.

It’s a common trope in various antidepressant ads. An individual is living in a black and white world characterized by blandness. But, as soon as their depression is alleviated, reality becomes a rainbow. These findings aren’t quite as dramatic, but no less thought-provoking.

Researchers compared the visual processing and subsequent perception of a group of depressed individuals to a control group via two visual tests. One of those tests entailed study participants comparing the brightness and contrast of a series of fairly simple patterns.

“What came as a surprise was that depressed patients perceived the contrast of the images shown differently from non-depressed individuals,” says Viljami Salmela, a Research Fellow at the Academy of Finland.

Depressed participants saw “weaker” patterns than the control group, which subsequently led to the depressed subjects also reporting the contrast as being stronger than it was.

“The contrast was suppressed by roughly 20% among non-depressed subjects, while the corresponding figure for depressed patients was roughly 5%,” Salmela explains.

The full impact and implications of how depression influences the mind and all of its parts are still very much a work in progress for modern science. For every single agreed-upon effect, there are two more lingering questions. So, study authors say their work connecting depression and vision deserves further attention and additional research.

“It would be beneficial to assess and further develop the usability of perception tests, as both research methods and potential ways of identifying disturbances of information processing in patients,” Salmela adds.

For instance, the research team is optimistic that vision assessments may one day prove useful for evaluating the effectiveness of a particular depression treatment. That being said, they also caution that vision tests probably shouldn’t be used to diagnose depression.

“However, depression cannot be identified by testing visual perception, since the observed differences are small and manifested specifically when comparing groups,” Salmela concludes.

Sight isn’t the only sense that depression is known to influence. This 2020 study found a connection between depression and “smell dysfunction” among older adults.

The full study can be found here, published in the Journal of Psychiatry & Neuroscience.