An Observational Study of Cognitive Impairment in Amyotrophic Lateral Sclerosis

Abstract

Background: Cognitive impairment is increasingly recognized in patients with amyotrophic lateral sclerosis (ALS). Clinical and pathologic features overlap in frontotemporal lobar dementia and ALS. Demographics, respiratory status, bulbar site of onset, and disease severity are potential risk factors for cognitive impairment in ALS. Objectives: To further delineate the frequency, nature, and implications of cognitive impairment in ALS and to assess previously identified risk factors. Design: Case-control and retrospective cohort study. Setting: Academic referral center. Participants: Forty consecutive patients with ALS underwent baseline neurologic and neuropsychologic examinations. Cognitive test performance was compared in patients with ALS and matched controls. An exploratory analysis of the relationship between cognitive performance and ALS survival was performed. Main Outcome Measures: Neuropsychologic test performance, ALS severity, and survival. Results: Twelve patients (30%) showed evidence of cognitive impairment, including 9 (23%) who met the neuropsychologic criteria for dementia. No statistically significant differences were found between demented and nondemented ALS groups regarding demographics, family history, site of onset, bulbar dysfunction, or ALS severity. Only 1 patient with dementia had bulbar-onset disease. An association was observed between increasing ALS severity and declining verbal fluency performance. Demented patients with ALS showed predominant impairment in free recall, executive function, and naming, with relative preservation of attention, psychomotor speed, and visuospatial function. No association was observed between cognition and survival, controlling for ALS severity. Conclusions: Nearly a third of the patients with ALS showed evidence of cognitive impairment in a pattern consistent with frontotemporal lobar dementia. Cognitive performance was not related to site of onset or survival.

Screening for cognitive and behavioural impairment in amyotrophic lateral sclerosis: Frequency of abnormality and effect on survival

“…This is consistent with some previous studies [56,57] but contrary to other studies [35,58]. In our study, stereotypical behaviour, apathy, and disinhibition do not predict the survival of ALS patients, which is consistent with one previous study using the same scale [59].…”

“…Previously, some studies have found that people with bulbar onset of ALS are more likely to have cognitive impairment than those with spinal onset [39,53,54], but others do not [33,35,55]. In our study, the site of onset had no effect of the presence of cognitive impairment as determined by the ACE-III, but site of onset influenced cognitive impairment based on FAB logistic regression results.…”

“…Age and lower levels of education have been observed in several previous ALS studies as risk factors for cognitive impairment [13,21,50], although others found no significant effect of these factors [35,51,52]. Using age corrected or education level corrected scoring guide would be desirable in future studies of cognition in ALS.…”

“…Some studies have found cognitive impairment to be more common in people with bulbar onset than limb onset of ALS [32]. However, other studies suggest that site of onset has no influence on the presence of cognitive impairment [33][34][35]. Therefore further information is required.…”

“…Some studies have suggested that the presence of cognitive impairment [36] or behavioral abnormality is associated with worse prognosis [37]. However, other studies suggest that cognitive impairment has no influence on survival [35]. Therefore further information is required.…”