Alzheimer's Disease and the Frontotemporal Dementias: Contributions to Clinico-Pathological Studies,Diagnosis,and Cognitive Neuroscience

Abstract

This review focuses on six key papers published in the mid 2000 s based on work conducted in Cambridge. The first two relate to clinico-pathological studies which established that Alzheimer's disease (AD) is a relatively common cause of focal cortical syndromes, notably progressive aphasia (largely nonfluent), progressive apraxia, and posterior cortical atrophy with complex visual symptoms. Building on these findings, criteria for the progressive aphasias have been developed which define the variant associated with AD (progressive logopenic aphasia). Memory in the dementias has been a major area of interest and one paper discussed here explored the neural basis for episodic and semantic memory failure in AD and semantic dementia. Despite very different memory profiles, the two disorders both cause severe hippocampal hypometabolism and atrophy but differ in the degree of involvement of other memory related structures. This work drew attention to the role of pathology in non-hippocampal structures early in AD. The next two articles deal with the behavioral variant frontotemporal dementia (bvFTD) which we have shown is associated with breakdown in theory of mind, social reasoning, empathy, and emotion processing and contributed to work on the neural basis of social cognition. We also identified a subgroup of bvFTD who fail to progress over many years, termed phenocopy cases, who are differentiated by their lack of atrophy on MRI. The final paper described the application of the Addenbrooke's Cognitive Examination-Revised, which has proven a useful brief assessment tool for the early detection of a range of neurodegenerative disorders including AD and FTD. It also appears to be helpful in predicting those with mild cognitive impairment who will progress to frank dementia.