Cognition and behaviour in motor neurone disease

Motor neurone disease has traditionally been considered a pure motor syndrome which spares aspects of cognition and behaviour, although in recent years it has been suggested that up to 50% of patients with motor neurone disease may develop frontal dysfunction which, in some cases, is severe enough to reach criteria for frontotemporal dementia. We review the cognitive and behavioural changes in motor neurone disease emphasizing the recent advances.A major advance in pathology has been the recent discovery of TDP-43 and FUS inclusions as the key components in cases of motor neurone disease, frontotemporal dementia-motor neurone disease and some cases with pure frontotemporal dementia. In addition, mutations in TARDBP and FUS genes have been reported in recent years. Longitudinal studies showed that progression of cognitive impairment over the course of motor neurone disease appears to be mild and occurs only in a proportion of motor neurone disease patients. The presence of cognitive impairment seems to be related to a faster disease and a shorter survival.Motor neurone disease is a multi-system disorder which overlaps with frontotemporal dementia. Behavioural and cognitive changes appear to occur in a subset of patients with motor neurone disease, but the cause of this variability remains unclear.