Prognosis

Assessing and predicting the individual prognosis of a patient with behavioral variant frontotemporal dementia (bvFTD) is one of the most difficult tasks in this disease entity. Progression of cognitive decline in bvFTD can be classified as slow or fast. Males progress slowly compared with females.[226]​ There is insufficient evidence about the impact of age of onset on the longitudinal course of FTD.[227]​ Faster cognitive decline is associated with reduced baseline gray-matter volume and increased microglial activation in frontal regions, bilaterally. Atrophy and microglial activations are independent predictors of cognitive decline in all three major variants of FTD assessed as performance in attention/orientation tests. Specifically, the combination of these pathologic in vivo indices measured using structural magnetic resonance imaging (MRI) and [11C]PK11195 positron emission tomography (PET) may be a useful marker to stratify patients with FTD into those likely to exhibit slow versus fast decline.[228]

The life expectancy of people with FTD is not clear. Median survival from diagnosis of FTD has been reported to be 7-13 years in clinic cohorts and 6-8 years in neuropathology series.[229][230][231][232]​ Survival differs for FTD phenotypes. One meta-analysis found survival to be shortest in the FTD amyotrophic lateral sclerosis variant (2.5 years). Mean survival was longest in patients with bvFTD and progressive nonfluent aphasia (8 years), and a median survival of 12 years was found in those with semantic dementia. Progressive supranuclear palsy and corticobasal degeneration had a similar survival, which was generally shorter than for bvFTD.[233]​ One study indicated that life expectancy may be shorter in patients with bvFTD than in those with progressive nonfluent aphasia or semantic dementia.[234] Median survival is considerably shorter (3 years) in patients with FTD and concomitant motor neuron disease, although a subset survived for up to 5 years, and sudden death may be common.[230]​ Patients with FTD generally have shorter survival and faster rates of cognitive and functional decline than patients with Alzheimer disease.[235]

One meta-analysis of 1060 c9orf72RE carriers found that survival differs according to clinical phenotype. In addition, older age at onset was associated with shorter survival in c9ALS, c9FTD, and c9ALS-FTD phenotypes, and bulbar onset was associated with shorter survival in c9ALS phenotype.[236]​ Homozygosity for rs12608932-C in UNC13A polymorphism in FTD was associated with a shorter survival compared with other genotypes.[237]​ Other factors that may contribute to shorter survival include negative behaviors like apathy, aspontaneity, inattention, logopenic, aphasia/verbal apraxia, rigidity, and bradykinesia.[238]

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