Distinctiveness of the Edinburgh Cognitive and Behavioural Amyotrophic Lateral Sclerosis Screen (ECAS) To differentiate cognitive functioning in Amyotrophic Lateral Sclerosis and mimics

Cognitive deterioration in Amyotrophic Lateral Sclerosis (ALS) has been related to negative outcomes for patients and their carers. Accurate detection of cognitive impairment in these patients is therefore desirable. Primary aim of this study was to assess whether the Edinburgh Cognitive and Behavioural Amyotrophic Lateral Sclerosis Screen (ECAS) can differentiate between cognitive decline specific for ALS, and reduced cognition due to secondary factors in chronic motor disorders (such as fatigue). Second, the predictive value of ECAS composite scores (ALS specific, ALS-non specific and ECAS total) was evaluated to classify subjects as patients with ALS or a motor disease that resembles ALS (mimics). 406 ALS patients, 152 mimics and 100 healthy controls completed the hospital anxiety and depression scale (HADS) and cognitive section of the ECAS. ECAS composite- and domain scores were compared between groups. HADS scores were analysed to rule out confounding variables. Results showed that mimics and ALS patients scored below healthy controls, and ALS patients below mimics, on all scores except visuospatial functions. Logistic regression analyses proved that ECAS composite scores are significant predictors to distinguish ALS patients from mimics. Due to the lack of qualitative differences in cognition, the ECAS can not be used to differentiate between ALS specific and non-specific cognitive decline. Memory is more affected in ALS than expected. Suppressed cognitive performance in all patients may be caused by secondary disease factors. Cognitive decline as a symptom of ALS may account for the difference in level of cognitive functioning between ALS patients and mimics.