Screening for cognitive dysfunction in ALS: validation of the Edinburgh Cognitive and Behavioural ALS Screen (ECAS) using age and education adjusted normative data

Background: Cognitive and behavioural changes are an important aspect in Amyotrophic Lateral Sclerosis (ALS). The Edinburgh Cognitive and Behavioural ALS Screen (ECAS) briefly assesses these changes in ALS. Objective: To validate the ECAS against a standardised neuropsychological battery and assess its sensitivity and specificity using age and education adjusted cut-off scores. Method: 30 incident ALS cases were assessed on both, ECAS and neuropsychological battery. Age and education adjusted cut-off scores were created from a sample of 82 healthy controls. Results: ECAS composite scores (Total, ALS Specific and Non-Specific) were highly correlated with battery composite scores. High correlations were also observed between ECAS and full battery cognitive domains and subtests. The ECAS Total, ALS Specific and Non-Specific scores were highly sensitive to cognitive impairment. ECAS ALS-Specific cognitive domains also evidenced high sensitivity. Individual subtest sensitivity was medium to low, suggesting that caution should be used when interpreting these scores. Low positive predictive values indicated the presence of false positives. Conclusions: Psychometric properties of the ECAS using age and education adjusted norms indicate that the ECAS, when used as an overall measure of cognitive decline, is highly sensitive. Further comprehensive assessment is required for patients that present as impaired on the ECAS.