Vol 9, No 2 - Neuropsychiatric Manifestations of Neurodegenerative Disease
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he  term  frontotemporal  dementia  (FTD)1-3 refers to a complex of behavioral-cognitive symptoms produced  by  progressive  degeneration  of  the  frontal and/or temporal regions. The syndrome originally described by Pick,4 and thus termed Pick’s disease in the following decades, was char- acterized by atrophy and argentophilic intraneuronal inclusions (Pick’s bodies). Indeed, the histopathological features of the frontal dementias are not distinctive, and a continuum towards other neurological conditions, such as the tauopathies or motor neuron diseases, has now been documented,5,6 suggesting extensive pathological and etiological heterogeneity. In spite of this, there is quite a large consensus that the clinical presentations of FTD should be restricted to three main subtypes principally reflecting the distribu- tion of neuronal loss, ie, of atrophy, in the brain: (i) the behavioral or frontal variant (fv-FTD) due to prevalent prefrontal damage, dominated by behavioral symptoms and  dysexecutive  disorders;  (ii)  primary  progressive aphasia (PPA),7 characterized by a progressive nonfluent linguistic  impairment  associated  with  left  perisylvian atrophy;8 and (iii) semantic dementia (SD), in which a progressive agnosia for words and objects follows left anterior temporal lobe degeneration.9 Well-identified patterns of cognitive disorders, largely confined to the linguistic domain, characterize the onset of both PPA and SD, which are both generally compli- cated by the emergence of behavioral manifestations only at later stages.10,11 On the other hand, the early man- ifestation  of  the  frontal  variant  frequently  involves noncognitive   behavioral   domains   and   personality changes that may dominate the clinical picture for a long time before true cognitive decline appears.12 FTD is con- sidered to be the second most frequent type of degener- ative dementia.13 However, it should be taken into con- C l i n i c a l   r e s e a r c h T Copyright © 2007 LLS SAS.  All rights reserved www.dialogues-cns.org Frontotemporal dementia to Alzheimer’s disease Maria Caterina Silveri, MD Keywords:  frontotemporal dementia; Alzheimer’s disease; behavioral disorder; theory of mind; social cognition Author affiliations: Memory Clinic, Centre for Medicine of the Ageing, Catholic University, Rome, Italy Address for correspondence: Dr Maria Caterina Silveri, Memory Clinic, Centre for Medicine of the Ageing, Catholic University, Largo
A. Gemelli, 8, 00168 Rome, Italy (e-mail: silveri@rm.unicatt.it) Behavioral manifestations may dominate the clinical pic- ture of the frontal variant of frontotemporal dementia (fv- FTD) for a long time before the appearance of true cog- nitive deficits. On the other hand, a deficit in the episodic memory domain represents the main manifestation of Alzheimer’s disease (AD). Many behavioral disorders have been described in the clinical course of both FTD and AD; however,  apathy  and  personality  changes  characterize frontal dementias, while depression dominates in AD, at least in the earlier stages. Depending on the distribution of neural damage, different patterns of noncognitive man- ifestations may be expected in different subtypes of FTD. Recent research on the social cognition deficit in FTD has offered new insights into the relationship between cog- nition and behavior, suggesting that some aspects of the behavioral changes in dementia may be generated by impairment in this domain. © 2007, LLS SAS Dialogues Clin Neurosci. 2007;9:153-160.