Gesture profiles distinguish primary progressive aphasia variants: A preliminary study

Area of Science:

• Neuroscience
• Linguistics
• Cognitive Science

Background:

• Primary progressive aphasia (PPA) is a neurodegenerative syndrome causing progressive language decline.
• PPA variants (semantic, logopenic, nonfluent) are difficult to differentiate.
• Limb apraxia frequently co-occurs with PPA, but variant-specific gesture deficits remain unclear.

Purpose of the Study:

• To investigate if PPA variants exhibit distinct gesture imitation deficits.
• To test if semantic PPA (svPPA), associated with temporal lobe atrophy, shows impaired benefit from gesture meaning.
• To compare performance on meaningful vs. meaningless gestures and hand postures vs. arm kinematics.

Main Methods:

• Participants with PPA imitated meaningful and meaningless gestures.
• Gesture imitation was scored for hand posture and arm kinematics.
• Bayesian mixed-effect models analyzed accuracy, controlling for dementia severity and variant-specific effects.

Main Results:

• A significant interaction was found between PPA variant, gesture meaning, and component.
• svPPA participants' hand postures did not benefit from gesture meaning, unlike lvPPA and nfvPPA.
• This suggests distinct praxis patterns across PPA variants.

Conclusions:

• Gesture imitation patterns differ between PPA variants.
• svPPA shows a unique deficit in utilizing gesture meaning for hand postures.
• Findings inform PPA diagnostics, communication strategies, and praxis models.