The World Really Does Look Different When You’re Depressed

“I’ve got the blues.”

“The world looks so gray.”

If you’ve ever heard someone who is depressed say the world just doesn’t look as bright as it used to, it might be because depressed people literally see the world differently. The retinas of people who are depressed just don’t respond as well to visual stimuli as those of people who are not depressed. A group of German researchers from Albert Ludwig University of Freiburg reported the connection in a recent issue of the journal Biological Psychiatry.

Using a test for electrical activity in the eye that involves attaching a tiny elecrode to the eyeball, the German scientists led by Dr. Tebartz van Elst tested patients who had been diagnosed with depression and other patients who were not depressed as they looked at black-and-white checkerboard patterns on computer screens. The contrast between the black and white squares varied throughout the test.

After the test, the researchers compared the electrical activity in the eyes of the depressed and non-depressed subjects and found a clear trend. The depressed subjects had less responsive retinas. The lower responsiveness of the retinas of depressed subjects was consistent whether or not the subjects with depression were taking medication for their condition.

Dopamine, a chemical most often associated with brain function, is also important in the retina and its perception of contrast, so the German researchers say their study may suggest that dopamine plays a role in depression.

In addition, testing retinal responsiveness may eventually be part of diagnostic measurements of depression–although the German research group says this test is only preliminary and further study is needed before retinal testing could reliably be used to diagnose depression.

Testing the retina’s responsiveness may offer a more objective measure of depression, unlike self-reports of mood.  In addition, retinal testing may allow for testing in cases where self-report is unreliable or unavailable. The test could be particularly useful in animal studies of depression as an indicator of an animal’s physiological condition.

Perhaps someday, as treatments for depression continue to improve, we may be able to determine that the world really does look bright again for people recovering from depression.