Seeing grey when feeling blue

In language and arts depression is associated with darkness and grey and black colours. Everything looks grey when people feel blue.
There might be an empirical truth behind these idioms according to the findings of a research group at the University Hospital Freiburg in Germany, who combined neuropsychiatric and ophthalmologic investigations. In earlier work they were able to demonstrate that depressed people do have difficulties with detecting black-and-white contrast differences. In another study published in 2010 they focused on the response of the retina in depressed and healthy humans to varying black-and-white contrasts. Measuring the pattern of an electroretinogram, which is a kind of electrocardiogram (ECG) of the eye, they found dramatic reductions in response amplitudes of the eyes of depressed patients. The signal was so strong that it was able to distinguish most depressed patients on a single case basis from healthy control subjects when looking at the electrophysiological measurement.
In the latest study just published in the renowned British Journal of Psychiatry (http://bjp.rcpsych.org/content/201/2/151.full) they now report that the abnormal retinal signal normalised following remission of depression. Therefore the objectively measurable retinal contrast gain might prove to be an objective state marker of depression.
Should these findings be replicated in further studies, this method could turn out to be a valuable tool to objectively measure the subjective state of depression. This could have far reaching implications for research as well as clinical diagnosis and therapy of depression.

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