Behavioral Variant Frontotemporal Dementia with Corticobasal Degeneration Pathology: Phenotypic Comparison to bvFTD with Pick’s Disease

Abstract

Patients with corticobasal degeneration (CBD) pathology present with diverse clinical syndromes also associated with other
neuropathologies, including corticobasal syndrome, progressive nonfluent aphasia, and an Alzheimer’s-type dementia. Some present
with behavioral variant frontotemporal dementia (bvFTD), though this subtype still requires more detailed clinical characterization.
All patients with CBD pathology and clinical assessment were reviewed (N = 17) and selected if they initially met criteria for bvFTD [bvFTD(CBD), N = 5]. Available bvFTD patients with Pick’s [bvFTD(Pick’s), N = 5] were selected as controls. Patients were also compared to healthy older controls [N = 53] on neuropsychological and neuroimaging measures. At initial presentation, bvFTD(CBD) showed few neuropsychological
or motor differences from bvFTD(Pick’s). Neuropsychiatrically, they were predominantly apathetic with less florid social disinhibition
and eating disturbances, and were more anxious than bvFTD(Pick’s) patients. Voxel-based morphometry revealed similar patterns
of predominantly frontal atrophy between bvFTD groups, though overall degree of atrophy was less severe in bvFTD(CBD), who
also showed comparative preservation of the frontoinsular rim, with dorsal > ventral frontal atrophy, and sparing of temporal
and parietal structures relative to bvFTD(Pick’s) patients. Despite a remarkable overlap between the two patient types, bvFTD
patients with underlying CBD pathology show subtle clinical features that may distinguish them from patients with Pick’s disease
neuropathology.

KeywordsCorticobasal degeneration–Frontotemporal dementia–Behavior–Neuropsychiatry–Neuropsychology–Neuropathology