👤 M L Gorno-Tempini

White matter hyperintensities (WMH) in patients with cerebrovascular risk factors (CVRF), are often linked to cerebral vascular changes, but can be caused by genetic variants selectively targeting white matter. In addition, WMH can be present in neurodegenerative disorders such as frontotemporal lobar degeneration (FTLD) and are linked to some FTLD genetic variants. This study aims to investigate WMH burden in patients with behavioral variant frontotemporal dementia (bvFTD) and semantic variant primary progressive aphasia (svPPA) versus controls and to evaluates the influence of CVRF. This cross-sectional retrospective analysis examined individuals meeting research diagnostic criteria for bvFTD and svPPA with high-quality structural MRI at the UCSF Memory and Aging Center between September 2008 and December 2021. WMH burden and spatial distribution were assessed by disease group compared to age- and sex-matched controls and associations with CVRF evaluated. We included 109 individuals with bvFTD [mean age (SD) 62.9 (8.6), 40% female], 47 with svPPA [mean (SD) age 65.4 (7.5), 51% female], and matched controls. After adjusting for age, bvFTD and svPPA are associated with elevated WMH burden independent of CVRF. In bvFTD, WMH are primarily distributed within the frontal lobes, while svPPA shows widespread distribution across lobes. Study limitations include its retrospective, single-center design and limited power for genetic subgroup analyses. Show less

Frontotemporal dementia (FTD) is a clinical syndrome characterized by progressive decline in social conduct and a focal pattern of frontal and temporal lobe damage. Its biological basis is still poorly understood but the focality of the brain degeneration provides a powerful model to study the cognitive and anatomical basis of social cognition. Here, we present Dr. A, a patient with a rare hereditary bone disease (hereditary multiple exostoses) and FTD (pathologically characterized as Pick's disease), who presented with a profound behavioral disturbance characterized by acquired sociopathy. We conducted a detailed genetic, pathological, neuroimaging and cognitive study, including a battery of tests designed to investigate Dr. A's abilities to understand emotional cues and to infer mental states and intentions to others (theory of mind). Dr. A's genetic profile suggests the possibility that a mutation causing hereditary multiple exostoses, Ext2, may play a role in the pattern of neurodegeneration in frontotemporal dementia since knockout mice deficient in the Ext gene family member, Ext1, show severe CNS defects including loss of olfactory bulbs and abnormally small cerebral cortex. Dr. A showed significant impairment in emotion comprehension, second order theory of mind, attribution of intentions, and empathy despite preserved general cognitive abilities. Voxel-based morphometry on structural MRI images showed significant atrophy in the medial and right orbital frontal and anterior temporal regions with sparing of dorsolateral frontal cortex. This case demonstrates that social and emotional dysfunction in FTD can be dissociated from preserved performance on classic executive functioning tasks. The specific pattern of anatomical damage shown by VBM emphasizes the importance of the network including the superior medial frontal gyrus as well as temporal polar areas, in regulation of social cognition and theory of mind. This case provides new evidence regarding the neural basis of social cognition and suggests a possible genetic link between bone disease and FTD. Show less