Clinical characteristics of parkinsonism in frontotemporal dementia according to subtypes

We investigated the prevalence of parkinsonism in frontotemporal dementia (FTD) subtypes and the cognitive and behavioral differences between FTD with and without parkinsonism in a well-structured, prospective cohort.

One hundred and ninety-one FTD patients were enrolled and all patients underwent comprehensive neurological evaluations, neuropsychological tests, and the Unified Parkinson's Disease Rating Scale.

The prevalence of parkinsonism was 38.7% (74 patients), and included 33 (46.5%) behavioral variant FTD (bvFTD), 16 (24.2%) semantic dementia (SD), 19 (45.2%) progressive nonfluent aphasia (PNFA), and 6 (50%) FTD associated with motor neuron disease (FTD-MND). SD patients with parkinsonism had higher CDR sum of boxes scores (9.7±4.5 vs 6.2±4.5, p=0.024), frontal behavioral inventory total score (33.7±20.5 vs 24.3±14.5, p=0.045), and executive function score of frontal executive dysfunction, disinhibition, and apathy (28.9±13.7 vs 19.2±12.9, p=0.021) than those without parkinsonism. Seoul Instrumental Activities of Daily Living score (bvFTD: 23.5±11.7 vs 17.3±11.3, p=0.031, SD: 23.1±11.1 vs 11.3±9.3, p=0.005) was higher for bvFTD and SD with parkinsonism than for those without parkinsonism.

Parkinsonism is found to be more common in patients with bvFTD, PNFA, and FTD-MND patients than those with SD. Behavioral disturbances were more prominent in SD with parkinsonism than without. Additional studies are needed to determine the pathomechanism and optimal treatment of parkinsonism in different FTD subtypes.