Multimodal MRI quantification of the common neurostructural bases within the FTD-ALS continuum

Area of Science:

• Neuroimaging
• Neurodegenerative Diseases
• Brain Anatomy

Background:

• The continuum hypothesis suggests a link between behavioral variant of frontotemporal dementia (bvFTD) and amyotrophic lateral sclerosis (ALS).
• Previous evidence from clinical, pathological, genetic, and neuroimaging studies supports this connection.
• Understanding shared neurostructural changes is crucial for diagnosing and treating these related neurodegenerative conditions.

Purpose of the Study:

• To investigate the site and extent of shared gray and white matter neurostructural changes in bvFTD and ALS patients without dementia.
• To compare neurostructural damage patterns between bvFTD and ALS patients and healthy controls.
• To correlate the degree of brain damage with symptom severity in both patient groups.

Main Methods:

• Multimodal magnetic resonance imaging (MRI) was employed.
• Twenty bvFTD patients and nineteen ALS patients without dementia were included.
• Structural MRI data were analyzed to identify macrostructural and microstructural damage in gray and white matter.

Main Results:

• An overlap of macrostructural and microstructural damage was observed in both bvFTD and ALS patients compared to controls.
• Shared areas of damage included the right orbital cortex, bilateral anterior cingulate cortices, corticospinal tract, and corpus callosum.
• Greater atrophy in orbitofrontal and frontomedial regions correlated with severe executive/behavioral symptoms, while motor pathway degeneration correlated with motor neuron disorder severity.

Conclusions:

• The findings provide additional evidence supporting the FTD-ALS continuum hypothesis.
• The study supports the concept of a bimodal yet convergent pattern of neurostructural changes in bvFTD and ALS.
• Shared neuroimaging markers highlight the interconnectedness of these neurodegenerative diseases.