Attentional Function in Patients With Amyotrophic Lateral Sclerosis is Moderated by Age and Education

Besides motor brain regions, amyotrophic lateral sclerosis (ALS) affects non-motor regions such as front temporal regions, affecting various cognitive domains.

We performed a behavioral study using the attention network test (ANT) to examine two components of attention (alerting, executive condition) and two degrees of difficulty (conflict condition) in 27 patients with ALS with no reported symptoms suggestive of cognitive impairment and 26 matched control participants.

Using a modified ANT that accounted for ALS-induced motor impairment by focusing on relative reaction times, we could demonstrate its feasibility even in severely paralyzed patients. Relative reaction time differences were comparable to controls, demonstrating the task's ability to correct for motor bias. When focusing on relative reaction times, in both groups we found intact executive and conflict effects. Furthermore, ALS patients had comparable task accuracies when reacting to congruent and incongruent easy targets. However, the task accuracy of ALS patients was significantly lower compared to controls when reacting to the incongruent hard target. This effect was enhanced by the interaction effect of ALS diagnosis and age.

Our results suggest a significant interaction between age and ALS pathology, potentially leading to a breakdown of cognitive resources at higher levels of executive demand. We hypothesize that subclinical executive vulnerability in ALS patients becomes apparent when additional detrimental factors, such as aging, are present in patients. While we did not test co-pathologies in our cohort, co-occurring neurodegenerative or vascular processes might have contributed to this result. Our findings highlight the importance of cognitive screening for ALS patients above 60 years, even in the absence of subjective and collateral history of cognitive impairment.