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

PURPOSE

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

METHODS

Pupil activity was monitored in three patients with ALS and a group of healthy control participants ( = 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.

RESULTS

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.

CONCLUSION

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.