Nonprogressive behavioural frontotemporal dementia - ResearchGate
Nonprogressive behavioural frontotemporal dementia: recent developments and clinical implications of the ‘bvFTD phenocopy syndrome’ Christopher M. Kipps a,b , John R. Hodges c,d and Michael Hornberger c,d a Wessex Neurological Centre, Southampton University NHS Trust, b Department of Clinical Neurosciences, University of Southampton, Southampton, UK, c Neuroscience Research Australia and d School of Medicine, University of New South Wales, Sydney, Australia Correspondence to Dr Christopher Kipps, Consultant Neurologist and Honorary Senior Clinical Lecturer, Wessex Neurological Centre, Southampton University NHS Trust, Southampton SO16 6YD, UK E-mail: email@example.com Current Opinion in Neurology 2010, 23:628–632 Introduction Behavioural variant frontotemporal dementia (bvFTD) is the most common presentation of frontotemporal dementia (FTD) [1,2]. Patients usually present with changes in behaviour and personality, including alterations of mood, motivation and inhibition, which are recognized in the current diagnostic criteria  (Table 1). These clinical diagnostic criteria have, in the past, been shown to reliably detect and discriminate bvFTD from other dementias ; however, they have never been prospectively validated. Recent studies [5,6] have also questioned whether there are patients who fulfill the bvFTD diagnostic criteria without an underlying neurodegenerative condition. Such patients are considered to have a bvFTD ‘phenocopy syndrome’, manifesting characteristic behavioural features without actively progressing to frank dementia. This raises concern that application of the current clinical criteria (or their revision) may identify patients without a neurodegenerative disorder. In the following article we will review recent evidence for the bvFTD phenocopy syndrome, highlight the diagnostic 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. Keywords diagnosis, frontotemporal dementia, imaging, neuropsychology, phenocopy Curr Opin Neurol 23:628–632 ß 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 1350-7540 challenges for clinicians, recommend diagnostic steps and discuss the implications for the clinical diagnostic criteria of bvFTD. Phenocopy syndrome Researchers at the Cambridge Dementia Group became aware of a group of bvFTD patients in whom there did not appear to be disease progression following clinical diagnosis despite a clear history from caregivers of initial personality and behavioural changes. Using a visual scale to rate the degree of atrophy in frontal and temporal lobes, it became clear that there was a distinct lack of frontotemporal atrophy on structural imaging in many of those patients . Crucially, imaging changes are not currently mandatory for definite bvFTD diagnosis. More importantly, Kipps and colleagues  noted that other frontotemporal syndromes (particularly semantic dementia, but also progressive nonfluent aphasia), invariably showed significant atrophy by the time of diagnosis. By contrast, over half of the bvFTD patients had scans that overlapped with the control range (0–1) (see Fig. 1). 1350-7540 ß 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins DOI:10.1097/WCO.0b013e3283404309 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.