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.

FIGURE 1

Selected coronal and axial slices demonstrating the atrophy patterns upon first clinical evaluation for 4 patients with behavioral variant frontotemporal dementia syndrome. Each coronal slice and the axial slice below it belong to a single patient. The two patients on the left were found to have corticobasal degeneration neuropathology upon autopsy; the two patients on the right were found to have Pick’s neuropathology.

FIGURE 2

Voxel-based morphometry (SPM5) comparison of structural anatomy in 3 patients with bvFTD syndrome and CBD neuropathology versus 53 healthy older controls. Images are shown with a FWE-corrected lower threshold of p<0.05, corresponding to T=4.51. Regions in yellow/red show areas of volume loss in bvFTD(CBD) patients relative to healthy controls.

FIGURE 3

Voxel-based morphometry (SPM5) comparison of structural anatomy in 5 patients with bvFTD syndrome and Pick’s neuropathology versus 53 healthy older controls. Images are shown with a FWE-corrected lower threshold of p<0.05, corresponding to T=4.51. Regions in yellow/red show areas of volume loss in bvFTD(Pick’s) patients relative to healthy controls.

FIGURE 4

Behavioral and psychiatric symptoms reported on the Neuropsychiatric Inventory (NPI) for patients with bvFTD. Five bvFTD patients had CBD pathology (black bars) and 4 bvFTD patients had Pick’s pathology (gray bars).