The post illumination pupil response is reduced in seasonal affective disorder

Jul 2, 2013Psychiatry research

The pupil's response after light exposure is reduced in seasonal depression

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Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Individuals with seasonal affective disorder (SAD) demonstrated a reduced post illumination pupil response (PIPR) to blue light compared to healthy controls.

SAD participants showed a lower PIPR and percent change in PIPR when exposed to blue light stimuli.
The PIPR response varied based on the OPN4 I394T genotype, indicating a potential genetic influence on light sensitivity.
No variation in PIPR was linked to the OPN4 P10L genotype.
These findings suggest that SAD may be associated with decreased sensitivity in the light input pathway, affecting neurobiological and behavioral responses.

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Individuals with seasonal affective disorder (SAD) may have a decreased retinal sensitivity in the non-image forming light-input pathway. We examined the post illumination pupil response (PIPR) among individuals with SAD and healthy controls to identify possible differences in the melanopsin signaling pathway. We also investigated whether melanopsin gene (OPN4) variations would predict variability in the PIPR. Fifteen SAD and 15 control participants (80% women, mean age 36.7 years, S.D.=14.5) were assessed in the fall/winter. Participants were diagnosed based on DSM-IV-TR criteria. Infrared pupillometry was used to measure pupil diameter prior to, during, and after red and blue stimuli. In response to blue light, the SAD group had a reduced PIPR and a lower PIPR percent change relative to controls. The PIPR after the blue stimulus also varied on the basis of OPN4 I394T genotype, but not OPN4 P10L genotype. These findings may indicate that individuals with SAD have a less sensitive light input pathway as measured by the PIPR, leading to differences in neurobiological and behavioral responses such as alertness, circadian photoentrainment, and melatonin release. In addition, this sensitivity may vary based on sequence variations in OPN4, although a larger sample and replication is needed.

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The post illumination pupil response is reduced in seasonal affective disorder

Abstract

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