Hippocampal Sclerosis in Frontotemporal Dementia: When Vascular Pathology Meets Neurodegeneration

Area of Science:

• Neuropathology
• Neurodegenerative Diseases
• Vascular Neurology

Background:

• Hippocampal sclerosis (HS) is a common finding associated with aging, TDP-43 proteinopathy, and cerebrovascular issues.
• Early-onset frontotemporal dementia (FTD) presents complex neuropathological features.
• Understanding the interplay of pathologies in FTD is crucial for diagnosis and treatment.

Purpose of the Study:

• To investigate the relationship between HS and TDP-43 proteinopathy in early-onset FTD.
• To identify additional factors associated with HS in this patient cohort.
• To explore potential pathophysiological mechanisms linking TDP-43, cerebrovascular disease, and HS.

Main Methods:

• Analysis of neuropathological data from an autopsy cohort of early-onset FTD patients.
• Examination of relationships between HS, TDP-43 proteinopathy (hippocampal and frontotemporal), Alzheimer disease, cerebrovascular changes, and age.
• Introduction of quantitative neuronal cell counting in CA1 for objective HS assessment.

Main Results:

• A strong association was confirmed between HS and hippocampal TDP-43.
• A weaker association was observed between HS and frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP).
• HS was present in all FTLD-TDP type D cases, 50% of type A, and 6% of type B.
• Significant associations were found between HS and vascular changes.

Conclusions:

• TDP-43 proteinopathy, especially in the hippocampus, is strongly linked to HS in early-onset FTD.
• Cerebrovascular changes are also significantly associated with HS.
• Further research into the pathophysiological mechanisms connecting TDP-43, vascular disease, and HS is warranted.