Chromatic pupillometry findings in attention deficit hyperactivity disorder: Sex differences

Area of Science:

• Neuroscience
• Ophthalmology
• Genetics

Background:

• Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder linked to neural pathway dysfunctions.
• Autonomic nervous system disturbances are also observed in individuals with ADHD.
• This study investigates pupillary light responses (PLR) to assess retinal pathway integrity in ADHD.

Purpose of the Study:

• To evaluate pupillary light responses (PLR) in individuals with ADHD.
• To assess the integrity of outer retinal photoreceptor-to-pathway contributions in ADHD.
• To explore potential sex-specific differences in PLR within the ADHD group.

Main Methods:

• A cross-sectional study involving 43 participants (22 with ADHD, 21 controls).
• Monocular PLR was measured using an eye tracker with short- and long-wavelength flashes at varying intensities.
• Key pupillometric parameters included peak pupil constriction amplitude (PCA), velocity (PCV), latency (PCL), and redilation latency (RL 50%).

Main Results:

• Individuals with ADHD exhibited reduced PCA for short-wavelength stimuli and reduced PCA for long-wavelength stimuli at specific intensities.
• Significant differences in PCL, PCV, and RL 50% were observed for short-wavelength stimuli in the ADHD group.
• Exploratory analysis revealed sex-specific differences, with males showing reduced rod pathway contributions and females showing decreased rod contributions.

Conclusions:

• Altered PLR in ADHD suggests disrupted rod-mediated responses and deficits in the rod-cone transition range.
• Significant sex-specific differences in PLR highlight the need for further research considering sex as a factor in ADHD.
• Findings suggest a potential link between cholinergic/noradrenergic dysregulation and altered retinal signal processing in ADHD.