Cognition, language and behaviour in motor neurone disease: Evidence of frontotemporal dysfunction

Cognitive symptoms accompanying motor neurone disease (MND) have been recog nized and described since the late 19th century. Numerous reports from Euro pe, North America and Japan suggest existence of a syndrome that can be des cribed as MND/dementia. Typically, psychiatric and cognitive changes, stron gly reminiscent of frontotemporal dementia, precede the occurrence of the c lassical signs and symptoms of MND by several months. In a small number of patients a similar picture can be heralded by a progressive aphasia leading ultimately to mutism. While the syndromes of MND/dementia and MND/aphasia constitute a comparatively small group, subtle but consistent cognitive alt erations have also been observed in the majority of nondemented MND patient s. Although generally much less pronounced, their pattern, affecting mostly frontal-executive functions, resembles that of MND/dementia. Post mortem e xamination results, describing pathological changes in the frontal robes, a nd functional neuroimaging studies, showing abnormal pattern of frontal act ivation, add more weight to the hypothesis linking MND to the frontotempora l dementia.