From the Guidelines
Primary progressive aphasia (PPA) is categorized into three main types: semantic variant (svPPA), nonfluent/agrammatic variant (nfvPPA), and logopenic variant (lvPPA), each with distinct characteristics and associated pathologies, as outlined in the 2025 consensus-based recommendations for communication interventions across research and clinical settings 1. The semantic variant (svPPA) is primarily associated with frontotemporal lobar degeneration pathology and difficulties in word retrieval and understanding word meaning.
- Key features of svPPA include:
- Difficulties with word retrieval
- Understanding word meaning
- Associated with frontotemporal lobar degeneration pathology (specifically TDP-43 type C) The nonfluent/agrammatic variant (nfvPPA) is also usually associated with frontotemporal lobar degeneration pathology and is characterized by:
- Motor planning or programming
- Apraxia of speech (AOS)
- Difficulties with grammar (agrammatism) It is essential to note that primary progressive apraxia of speech (PPAOS) is considered part of the broader nfvPPA syndrome, as stated in the consensus research diagnostic criteria 1. The logopenic variant (lvPPA) is commonly associated with Alzheimer’s disease pathology and results in:
- Difficulties in word retrieval
- Phonological working memory Each type of PPA has different underlying pathologies and progression, highlighting the importance of accurate diagnosis and tailored management approaches for patients and caregivers, as emphasized in the 2025 study 1.
From the Research
Types of Primary Progressive Aphasia
The primary progressive aphasia (PPA) is a clinical syndrome characterized by a progressive decline in language and speech of neurodegenerative origin 2. There are three main variants of PPA, which are:
- Nonfluent/agrammatic variant (nfvPPA): characterized by dysfluent and effortful speech, often combined with agrammatism 3
- Semantic variant (svPPA): characterized by fluent, but circumlocutory speech, then severe anomia and word-finding difficulties, all being associated with a progressive loss of lexical-semantic knowledge 3
- Logopenic variant (lvPPA): characterized by decreased spontaneous speech output with frequent word-finding pauses, phonologic parahpasias, and repetition deficits 3
Clinical Features of PPA Variants
Each variant of PPA has specific linguistic/cognitive deficits, corresponding anatomical and most probable pathological features 4. The clinical features of each variant are:
- nfvPPA: associated with atrophy of the left inferior, opercular, and insular regions, and pathology is a tauopathy (FTLD-T), most often Pick's disease or CBD 3
- svPPA: associated with atrophy of the anterior regions of the temporal lobes, usually more prominent on the left side, and the majority of these patients have TDP-43 pathology 3
- lvPPA: associated with imaging abnormalities in the left temporo-parietal junction area, and the pathological changes have been often those of AD 3
Diagnosis and Classification of PPA
The diagnosis and classification of PPA are complex, and some individuals do not fit neatly into the subtyping scheme 5. International consensus criteria are widely employed to identify PPA subtypes, but classification is challenging, and possible explanations for these challenges are explored 5. Improved reliability of diagnoses will be increasingly important as trials for etiology-specific treatments become available 6, 4.