Study provides insights into depression via ophthalmology

Scientists from the Max Planck Institute of Psychiatry measured the pupillary reaction of participants while they were solving a task. In healthy participants, the pupils dilated during the task in anticipation of a reward, but this reaction was less pronounced in participants with depression.

“The reduced pupil reaction was particularly noticeable in patients who could no longer feel pleasure and reported a loss of energy,” says Andy Brendler, first author of the study. This feeling of listlessness is one of the most common symptoms of depression.

“This finding helps us to understand the physiological mechanisms behind listlessness better,” explains research group leader Victor Spoormaker. Among other things, the pupillary reaction is a marker for activity in the locus coeruleus, the brain structure with the highest concentration of noradrenergic neurons in the central nervous system.

Noradrenergic neurons react to the neurotransmitter norepinephrine, an essential component in the stress response and the upregulation of arousal, in other words, the activation of the nervous system. “The reduced pupillary response in patients with more listlessness indicates that the lack of activation of the locus coeruleus is an important physiological process that underlies the feeling of listlessness,” says Spoormaker.

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