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

OBJECTIVE: To screen for cognitive and behavioural impairment in people with amyotrophic lateral sclerosis (ALS) and controls with neuromuscular disease and to correlate these with clinical features.

METHODS: 108 people with ALS and 60 controls with other neuromuscular diseases were recruited and assessed with the Addenbrooke's cognitive examination-III (ACE-III), the frontal assessment battery (FAB), and the executive function component of the Edinburgh cognitive and behavioural ALS screen (ECAS). The Amyotrophic lateral sclerosis-Frontotemporal dementia questionnaire (ALS-FTD-Q) and the Motor Neuron Disease Behavioural instrument (MiND-B) were administered to the caregivers of people with ALS. The prevalence of abnormalities was determined and correlated with clinical features and survival. In 37 people with ALS, serial studies were performed.

RESULTS: The frequencies of cognitive impairment based on the ACE-III and FAB were 30.0% and 14.0%, in ALS and 11.7% and 3.3% in controls, respectively. Age and years of education influence the results of the ACE-III and ECAS executive function. In ALS, the frequencies of behavioural impairment based on ALS-FTD-Q and MiND-B were 32.1% and 39.4%, respectively. There is significant correlation of ALS-FTD-Q and MiND-B with the ALSFRS-R score. ALS participants with cognitive impairment measured with ACE-III had significantly shorter survival time than those without. ALS participants with behavioural impairment measured with ALS-FTD-Q had worse prognosis than those without. No significant difference was found between the first two serial cognitive tests based on ACE-III and FAB by using generalized estimating equation.

CONCLUSION: There is a greater frequency of cognitive impairment in people with ALS than in patients with other neuromuscular diseases. The cognitive and behavioural tests are potential biomarkers of the prognosis of ALS. The results of cognitive tests are stable over 6months and possibly longer.