Social cognition in the nonfluent and logopenic variants of primary progressive aphasia: A review of variant-specific profiles

Beyond their predominant language impairments, primary progressive aphasias (PPA) are also marked by non-linguistic cognitive deficits. Among these, social cognition deficits have been understudied, particularly in the non-fluent (nfvPPA) and logopenic (lvPPA) variants. This review synthesizes behavioural and imaging data on emotion recognition, empathy, and theory of mind (ToM) in nfvPPA and lvPPA, and examines their potential contribution to the differential diagnosis. Evidence suggests that both variants exhibit social cognition deficits. Emotion recognition deficits are observed from disease onset in nfvPPA and lvPPA, although performance varies across modalities and tasks. Empathy appears relatively preserved in early stages, with cognitive aspects showing more variability than affective empathy. Theory of mind is consistently impaired in nfvPPA but remains largely unexplored in lvPPA. Limited comparative research and lack of ToM studies in lvPPA constrain our understanding of variant-specific profiles. However, combining emotion recognition with other cognitive measures shows potential to improve classification of these variants. Similarly, a more rapid decline in empathy in nfvPPA could contribute to differential diagnosis as the disease progresses. Finally, hypotheses based on anatomo-clinical correlates suggest distinct ToM deficits between variants. By highlighting variant-specific profiles and gaps in research, this review provides a comprehensive framework to guide future research, improve diagnostic accuracy and inform clinical management of these syndromes. • Both PPA variants show social cognition deficits from disease onset • Social cognition profiles differ between the variants • Nonfluent variant shows faster empathy decline than logopenic variant • Task modality influences emotion recognition performance in both variants • Limited comparative research constrains understanding of variant profiles