Screening for frontal lobe and general cognitive impairment in patients with amyotrophic lateral sclerosis.

OBJECTIVES

Cognitive impairment occurs in up to 50% of patients with amyotrophic lateral sclerosis (ALS). Simple tools are required to identify such individuals, as cognitive impairment adversely impacts quality of life and survival. Our objective was to determine the potential utility of the Frontal Assessment Battery (FAB) and the Montreal Cognitive Assessment (MoCA) in evaluating frontal lobe and general cognitive impairment, respectively. We also assessed the feasibility of screening for cognitive impairment in those patients with advanced physical disability by modifying selected FAB and MoCA subtasks.

METHODS

Fifty-four consecutive ALS patients were screened; 44 completed the FAB and 39 completed the MoCA. We administered modified tasks to patients with severe hand weakness or dysarthria. The patients were classified as cognitively impaired on each measure based on published cut-off scores of 14.11 on the FAB and 26 on the MoCA.

RESULTS

Twenty-one percent and 53% of patients were impaired on the FAB and the MoCA, respectively. Scores from patients receiving modified instructions did not differ from those completing standard versions. There were statistically significant correlations between the MoCA total scores and forced vital capacity (FVC) and ALSFRS-R scores. There was no correlation between these variables and the FAB.

CONCLUSIONS

Both the FAB and MoCA detected cognitive impairment in ALS patients. While the MoCA classified more patients as cognitively impaired than the FAB, the latter was more feasible for assessing patients with physical impairment. Simple task modifications proved effective in allowing patients with speech and motor impairments to undergo screening. Future studies are required to validate both measures, establish optimal cut-off scores, and validate modifications.