Pupillary reactivity to sad stimuli as a biomarker of depression risk: Evidence from a prospective study of children.

The primary aim of the current study was to examine whether physiological reactivity to depression-relevant stimuli, measured via pupil dilation, serves as a biomarker of depression risk among children of depressed mothers. Participants included 47 mother-child dyads. All mothers had a history of major depressive disorder. Pupil dilation was recorded while children viewed angry, happy, and sad faces. Follow-up assessments occurred 6, 12, 18, and 24 months after the initial assessment, during which structured interviews were used to assess for children's levels of depressive symptoms as well as the onset of depressive diagnoses. Children exhibiting relatively greater pupil dilation to sad faces experienced elevated trajectories of depressive symptoms across the follow-up as well as a shorter time to depression onset. These findings were not observed for children's pupillary reactivity to angry or happy faces. The current findings suggest that physiological reactivity to sad stimuli, assessed using pupillometry, serves as a potential biomarker of depression risk among children of depressed mothers. Notably, pupillometry is an inexpensive tool that could be administered in clinical settings, such as pediatricians' offices, to help identify which children of depressed mothers are at highest risk for developing depression themselves.