Determinants of survival in behavioral variant frontotemporal dementia.

Abstract

Behavioral variant frontotemporal dementia (bvFTD) is a common cause of younger onset dementia. Little is known about its rate of progression but a recently identified subgroup seems to have an excellent prognosis. Other determinants of survival are unclear. We analyzed survival in a large group of clinically diagnosed bvFTD patients (n = 91) with particular attention to demographic and clinical features at presentation. Of the 91 cases, 50 have died, with pathologic confirmation in 28. Median survival in the whole group was 9.0 years from symptom onset, and 5.4 years from diagnosis. After the exclusion of 24 "phenocopy" cases, the analysis was repeated in a subgroup of 67 patients. The mean age at symptom onset of the pathologic group was 58.5 years and 16% had a positive family history. Their median survival was 7.6 years (95% confidence interval [CI] 6.6-8.6) from symptom onset and 4.2 years (95% CI 3.4-5.0) from diagnosis. The only factor associated with shorter survival was the presence of language impairment at diagnosis. Patients with definite frontotemporal dementia have a poor prognosis which is worse if language deficits are also present. This contrasts with the extremely good outcome in those with the phenocopy syndrome: of our 24 patients only 1 has died (of coincident pathology) despite, in some cases, many years of follow-up.