Depression affects vision by reducing contrast

The world really does appear more dull when we are depressed, according to a recent study. Tests on retinas showed depressed people were unable to see contrast as well as those who were not depressed.

Researchers believe this lack of contrast in vision could be a factor in causing, or maintaining, depression. It could also be one of the reasons artists depict depression with darkness. Scientists at the University of Freiburg, Germany, carried out tests on the retinas of depressed people and non-depressed people. They studied forty patients with a diagnosis of major depression (half of them were on medication) and 40 subjects who did not have a mood disorder. New Scientist explained that the researchers ran an electrode along one eye in each person. These electrodes measured activity in the nerves connecting photoreceptors, which detect different aspects of light, to the optic nerve. The subjects sat in a dimly lit room and watched a black and white chequered screen which became greyer in six distinct stages, reducing the contrast between each square. The researchers found that those without depression had three times the nerve activity of those with depression, indicating that depression lessens the ability to detect contrast. Those with the most severe symptoms of depression noticed the least contrast. The differences were so marked that it was possible to distinguish the severely depressed people from the non-depressed participants just by viewing the test results. Ludger Tebartz van Elst, a member of the research team, was quoted in The Independent as saying, "This method could turn out to be a valuable tool to objectively measure the subjective state of depression, having far-reaching implications for research as well as clinical diagnosis, and therapy for, depression." Darkness can be a cause of depression. Many people suffer from seasonal affective disorder during the winter because of the shortened hours of sunlight. Special lights can sometimes help with this condition. The results of the research were reported in the Biological Psychiatry journal. The Colour Affects web site provides information on the psychological properties of different colours. For grey it says, “Pure grey is the only colour that has no direct psychological properties. It is, however, quite suppressive. A virtual absence of colour is depressing and when the world turns grey we are instinctively conditioned to draw in and prepare for hibernation. Unless the precise tone is right, grey has a dampening effect on other colours used with it. Heavy use of grey usually indicates a lack of confidence and fear of exposure.”