Frontotemporal lobar degeneration

Frontotemporal lobar degeneration
Classification and external resources
Specialty	Psychiatry, Neurology
OMIM	600274
DiseasesDB	10034
MeSH	D003704
[]

Frontotemporal lobar degeneration (FTLD) is a pathological process that occurs in frontotemporal dementia. It is characterized by atrophy in the frontal lobe and temporal lobe of the brain, with sparing of the parietal and occipital lobes.

Common proteinopathies that are found in FTLD include the accumulation of Tau proteins and TARDBPs. Mutations in the C9orf72 gene have been established as a major genetic contribution of FTLD, although defects in the GRN and MAPT genes are also associated with it.

There are 3 main histological subtypes found at post-mortem:

Two physicians independently categorized the various forms of TDP-43 associated disorders. Both classifications were considered equally valid by the medical community, but the physicians in question have jointly proposed a compromise classification to avoid confusion.

Dementia lacking distinctive histology (DLDH) is a rare and controversial entity. New analyses has allowed many cases previously described as DLDH to be reclassified into one of the positively defined subgroups.

There have been numerous advances in descriptions of genetic causes of FTLD, and the related disease amyotrophic lateral sclerosis.

Mutations in all of the above genes cause a very small fraction of the FTLD spectrum. Most of the cases are sporadic (no known genetic cause).

For diagnostic purposes, magnetic resonance imaging (MRI) and ([18F]fluorodeoxyglucose) positron emission tomography (FDG-PET) are applied. They measure either atrophy or reductions in glucose utilization. The three clinical subtypes of frontotemporal lobar degeneration, frontotemporal dementia, semantic dementia and progressive nonfluent aphasia, are characterized by impairments in specific neural networks. The first subtype with behavioral deficits, frontotemporal dementia, mainly affects a frontomedian network discussed in the context of social cognition. Semantic dementia is mainly related to the inferior temporal poles and amygdalae; brain regions that have been discussed in the context of conceptual knowledge, semantic information processing, and social cognition, whereas progressive nonfluent aphasia affects the whole left frontotemporal network for phonological and syntactical processing.

...
Wikipedia