# Pupil response as a window into cognitive processing in amyotrophic lateral sclerosis

## TL;DR

This study shows that pupil dilation during cognitive tasks is similar in people with ALS and healthy individuals, suggesting it could be a useful tool for measuring cognitive load in ALS.

## Contribution

The study demonstrates that pupillometry can reliably reflect cognitive load in ALS patients, offering a non-invasive method for cognitive assessment.

## Key findings

- Both ALS patients and controls showed increased pupil size with higher cognitive load.
- No significant difference in pupil response was found between ALS patients and healthy controls.
- Pupillometry is suggested as a reliable marker of cognitive processing in ALS.

## Abstract

This preliminary study aimed to investigate whether the pupil size reflects cognitive load in patients with amyotrophic lateral sclerosis (ALS).

Pupil activity was monitored in three patients with ALS and a group of healthy control participants (n = 16) while performing three tasks: a forward span task, a backward span task, and a control task involving counting aloud. These tasks were designed to impose increasing cognitive demands, with the backward span task being the most challenging.

Analysis revealed no significant difference in pupil size between patients with ALS and controls for the forward or backward spans or the control condition. Both groups demonstrated a consistent pattern of increased pupil size during the backward span task compared to the forward span task, and during the forward span task compared to the control condition.

These findings suggest that pupil dilation reflects task-related cognitive load similarly in ALS patients and healthy controls. This supports the use of pupillometry as a non-invasive and sensitive marker of cognitive processing in ALS.

•Pupil dilation was monitored in ALS patients and healthy controls during cognitive tasks.•Both groups showed increased pupil size with higher cognitive load (backward > forward > control task).•No significant difference in pupil response between ALS patients and controls was found.•Findings suggest that pupillometry reliably reflects cognitive load in ALS.•Supports the potential of pupil size as a non-invasive marker of cognitive processing in neurodegenerative diseases.

Pupil dilation was monitored in ALS patients and healthy controls during cognitive tasks.

Both groups showed increased pupil size with higher cognitive load (backward > forward > control task).

No significant difference in pupil response between ALS patients and controls was found.

Findings suggest that pupillometry reliably reflects cognitive load in ALS.

Supports the potential of pupil size as a non-invasive marker of cognitive processing in neurodegenerative diseases.