Neuroimaging patterns along the ALS-FTD spectrum: a multiparametric imaging study.

Area of Science:

• Neuroscience
• Neurology
• Radiology

Background:

• Frontotemporal dementia (FTD) presents with significant clinical, genetic, and pathological diversity.
• Understanding the neuroimaging correlates of FTD subtypes is crucial for diagnosis and management.
• The spectrum of FTD often overlaps with Amyotrophic Lateral Sclerosis (ALS-FTD).

Purpose of the Study:

• To characterize the distinct neuroimaging signatures of major FTD phenotypes.
• To investigate these signatures across the spectrum of FTD and ALS-FTD.
• To correlate imaging findings with clinical and genetic profiles.

Main Methods:

• A prospective quantitative neuroimaging study involving 100 participants.
• Included cohorts: behavioral variant FTD (bvFTD), non-fluent-variant primary progressive aphasia (nfvPPA), semantic-variant primary progressive aphasia (svPPA), C9orf72-positive ALS-FTD (C9+ ALS-FTD), C9orf72-negative ALS-FTD (C9- ALS-FTD), ALS without cognitive deficits (ALSnci), and healthy controls (HC).
• Comprehensive multimodal neuroimaging, genetic testing, and neuropsychological evaluations were performed.

Main Results:

• Phenotype-specific spatial patterns of pathology were identified, showing focal rather than global atrophy.
• Significant degeneration in the motor cortex and corticospinal tracts was observed in bvFTD and nfvPPA.
• C9+ ALS-FTD patients displayed widespread extramotor pathology and precentral gyrus atrophy compared to ALSnci.
• Region of interest analyses revealed focal grey matter alterations in Broca's and Wernicke's areas for language variants.

Conclusions:

• Clinical manifestations of FTD are directly linked to specific patterns of white and grey matter degeneration.
• Neuroimaging provides critical insights into the underlying pathology of different FTD subtypes.
• These findings support phenotype-specific diagnostic and therapeutic strategies for FTD spectrum disorders.