Development of cognitive/behavioral disturbances in motor neuron diseases with pure motor onset: can we predict it?

Approximately 50 % of motor neuron disease (MND) patients manifest cognitive and/or behavioral impairment (C/BI). Notably, while some patients exhibit those disturbances from disease onset, others develop them during disease course, but the determinants of such phenomenon are still largely unknown.

This study aimed at identifying baseline predictors of subsequent C/BI development in MNDs.

Pure motor MND cases with longitudinal Edinburgh Cognitive and Behavioral ALS screen (ECAS) exams were included (N = 80). Based on longitudinal data, patients were categorized as either remaining motor ("non-converters", N = 55) or developing C/BI ("converters", N = 25). Demographic, genetic, baseline motor and cognitive/behavioral features (with relative progression rates) were compared between groups using Mann-Whitney U and Chi-squared tests. Logistic regression models were used to identify significant predictors of C/BI development.

Relative to non-converters, converters cases exhibited older age at symptoms onset/first visit (p = 0.02, p = 0.01), lower frequency of right limbs onset (p = 0.02), lower ECAS alternation (p = 0.01), spelling (p = 0.02) and fluency letter S (p = 0.05) scores, as well as higher alternation (p = 0.004) and spelling (p = 0.006) progression rates, albeit those contrasts did not survive correction for multiple comparisons. All variables except for the spelling score and progression rates were predictive of C/BI development (p from 0.002 to 0.03).

While no firm conclusions can be drawn due to the lack of results surviving correction, our study suggests that specific clinical features significantly predict C/BI development in MNDs. These findings may facilitate an earlier identification of patients at risk for extra-motor symptoms development, enabling a more tailored clinical management.