People living with depression process visual information differently compared to non-depressed people, according to a study conducted by psychiatry and psychology researchers at the University of Helsinki.
Published in the Journal of Psychiatry and Neuroscience, the researchers said the phenomenon is most likely linked with the processing of information in the cerebral cortex.
The study used visual tests for brightness and contrast of simple patterns, and found that patients with depression perceived the visual illusion presented in the patterns as weaker and, consequently, the contrast as somewhat stronger, than the control group who had not been diagnosed with depression.
“What came as a surprise was that depressed patients perceived the contrast of the images shown differently from non-depressed individuals,” says Academy of Finland Research Fellow Viljami Salmela.
“The contrast was suppressed by roughly 20% among non-depressed subjects, while the corresponding figure for depressed patients was roughly 5%,” Mr Salmela explained.
Identifying changes in brain function underlying mental disorders is expected to increase our understanding of the onset of disorders and enable the development of effective therapies. “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,” said Mr Salmela. They could also be used to assess the effect of various therapies. However, he cautioned that depression cannot be identified by testing visual perception, as the observed differences are small and manifested specifically when comparing groups.