Apraxia Patterns for the Differentiation between Alzheimer's Disease and Frontotemporal Dementia Variants

Area of Science:

• Neurology
• Cognitive Neuroscience
• Geriatrics

Background:

• Differentiating Alzheimer's disease (AD), behavioral variant Frontotemporal Dementia (bvFTD), and Primary Progressive Aphasia (PPA) is challenging, even with biomarkers.
• Apraxia, a supportive diagnostic feature for AD, is often underrepresented in other dementia types.

Purpose of the Study:

• To investigate the presence and characteristic profiles of limb, verbal, and non-verbal apraxia in AD, bvFTD, and PPA.
• To assess the diagnostic accuracy and predictive value of apraxia profiles in distinguishing these dementia types.

Main Methods:

• Administered the Test for Upper Limb Apraxia (TULIA) and Apraxia Battery for Adults-2 (ABA-2) to patients with AD, bvFTD, PPA, and healthy controls (HC).
• Compared composite and subdomain apraxia scores between patient groups and HC.
• Analyzed praxis profiles for diagnostic indicators.

Main Results:

• Apraxia assessments demonstrated high diagnostic accuracy for dementia detection (sensitivity: 63.6-100%, specificity: 79.2-100%) compared to HC.
• Patients with AD showed greater deficits in imitating and pantomiming gestures compared to bvFTD.
• PPA patients exhibited increased pathological outcomes in verbal and non-verbal apraxia compared to AD, and comparable praxis results to bvFTD despite greater overall decline.
• bvFTD patients showed higher pathological outcomes in verbal apraxia compared to AD.
• Apraxia severity correlated with cognitive decline.

Conclusions:

• Apraxia profile evaluation can aid in differentiating AD from FTD subtypes.
• TULIA and ABA-2 are reliable bedside tests for clinical practice in assessing apraxia in dementia.