Structural and functional brain abnormalities place phenocopy frontotemporal dementia (FTD) in the FTD spectrum

Area of Science:

• Neuroimaging
• Neurology
• Neurodegeneration

Background:

• Phenocopy frontotemporal dementia (phFTD) clinically mimics behavioral variant FTD (bvFTD) but lacks apparent neuroimaging abnormalities.
• Distinguishing phFTD from bvFTD is crucial for understanding the FTD spectrum.

Purpose of the Study:

• To identify gray matter (GM) volume and perfusion abnormalities in phFTD.
• To determine if phFTD belongs to the frontotemporal dementia (FTD) spectrum.

Main Methods:

• Compared 7 phFTD patients, 11 bvFTD patients, and 20 controls using 3T MRI and pseudo-continuous arterial spin labeling (pCASL).
• Quantified normalized GM volumes and perfusion, correcting for partial volume effects.
• Analyzed regional and supratentorial cortical changes, controlling for gender and scanner effects.

Main Results:

• PhFTD patients showed cortical atrophy, predominantly in the right temporal lobe.
• BvFTD patients exhibited extensive frontotemporal atrophy.
• Increased perfusion was observed in the left prefrontal cortex of phFTD patients compared to bvFTD and controls.

Conclusions:

• Overlapping cortical structural abnormalities in phFTD and bvFTD suggest a continuum of changes within frontotemporal regions.
• Functional changes in phFTD may indicate a compensatory response to early pathology.
• These findings support a potential neuropathological basis for phFTD, positioning it within the FTD spectrum.