Fronto-Temporal Degeneration (FTD)
by André Delacourte
Fronto-temporal degeneration (FTD) refers to the parts of the brain that are preferentially affected: the frontal and temporal lobes (at the front and side of the brain respectively).
These areas are responsible for different clinical manifestations such as behaviour, emotional responses and language skills. According to the main location of damage, the different clinical manifestations evolve, giving rise to particular forms of frontal dementia and specific language disorders such as semantic dementia (SD) and primary progressive aphasia (PPA). This is why the classification of FTD is in part related to specific clinical manifestations.
However, the pathological processes responsible for the “FTD” clinical profile are heterogeneous, and mainly related to different dysfunctions of tau gene or tau protein (mutations, aggregation, abnormal production).
These different abnormal processes of tau are revealed by different types of brain lesions that accumulate in the cortex of patients, and more especially in fronto-temporal areas (Pick bodies, neurofibrillary tangles, astrocytic plaques).
All these histopathological features give rise to a complementary classification based on the types of lesions, or the types of molecular abnormalities responsable for the lesions. This classification is called histological sub-types .
Therefore this histological classification comprises Pick’s disease with Pick bodies and FTDP-17. FTDP-17 is a mixed classification. “FTD” stands for the frontotemporal clinical symptoms, “P” for the additional parkinsonian manifestations and “17” stands for the number of the chromosome that bears tau gene with the pathological mutations responsible for this disease.
DLDH is characterised by the absence of tau lesions, but the main molecular defect is related to the sharp decrease of normal tau proteins.
Hereafter you will find the classification of the Fronto-Temporal degeneration :
- Fronto-Temporal Dementia
- Primary Progressive Aphasia
- Semantic Dementia
- FTD with parkinsonism on chromosome 17 (FTDP-17)
- Pick's Disease
- Dementia Lacking Distinctive Histology (DLDH)
Last Updated: vendredi 09 octobre 2009