Frontotemporal dementia.
OBJECTIVE
The syndromes of frontotemporal lobar degeneration are increasingly recognized as an important cause of early-onset dementia. Diagnostic consensus criteria have now been established for almost a decade, and form the framework for its clinical classification. While these criteria remain useful, a growing body of evidence suggests that revisions may be necessary to improve their validity and applicability.


RESULTS
In each individual syndrome, the core features are not uniformly present, and criteria that are currently used to exclude a condition, such as impaired episodic memory, are often present. Imaging, however, may warrant increased diagnostic prominence, particularly for diagnosis in semantic dementia and prognosis in behavioural syndromes. There is clinical and pathological overlap between the syndromes, but the clinical distinction between progressive nonfluent aphasia and semantic dementia is strengthening. Several series have refined our understanding of the correspondence between clinical syndromes and histopathological subtype: strong for tau-negative, ubiquitin-positive forms and more variable for tau-positive forms, yet prospective studies are still rare. The influence of genetic factors varies substantially across the syndromes.


CONCLUSIONS
Further research should aim to integrate detailed clinical, radiological, pathological and genetic information.
Knibb
Jonathan A
JA
aUniversity of Cambridge Department of Clinical Neurosciences, Addenbrooke's Hospital, Cambridge, UK.
Kipps
Christopher M
CM
Hodges
John R
JR
D018888:Aphasia, Primary Progressive / Q000175:diagnosis / Q000503:physiopathology; D001921:Brain / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*; D003704:Dementia / Q000145:classification* / Q000175:diagnosis* / Q000503:physiopathology; D003937:Diagnosis, Differential; D003952:Diagnostic Imaging / Q000592:standards* / Q000639:trends; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D024801:Tauopathies / Q000175:diagnosis / Q000503:physiopathology; D025801:Ubiquitin / Q000032:analysis / Q000378:metabolism
D025801:Ubiquitin