Nonprogressive behavioural frontotemporal dementia: recent developments and clinical implications of the 'bvFTD phenocopy syndrome'.

PURPOSE OF REVIEW: The clinical features of behavioural variant frontotemporal dementia (bvFTD) are well established; however, recent work has identified patients fulfilling diagnostic criteria for the disease who do not appear to progress clinically. This review describes means of distinguishing this group at an early stage from patients who are likely to deteriorate. RECENT
FINDINGS: Despite indistinguishable clinical profiles, studies in a cohort of bvFTD patients showed a particularly good prognosis in a subgroup of predominantly male patients in whom initial structural imaging was normal. This could not be explained by differences in disease duration, and was confirmed by subsequent PET studies. Retrospective review of clinical data in these groups verified that the current clinical diagnostic criteria are both insensitive to true progressive bvFTD, particularly in the early stages, and also poorly specific. In contrast, measures of activity of daily living performance, executive function and tests of social cognition appear to have better discriminatory value for patients who show clear clinical progression, with many individual diagnoses verified by post mortem examination in this group.
SUMMARY: It remains doubtful that the nonprogressive group have a neurodegenerative disease. The implication for the current clinical diagnostic criteria and their proposed revision is discussed.