מאמר חדש של יובל כ"ץ ופרופ' נעמה פרידמן

Classification of lexical retrieval impairments in primary progressive aphasia

(פורסם ב-Aphasiology)

:תקציר

 Background

Lexical retrieval impairments are a hallmark feature of Primary Progressive Aphasia (PPA) and play a central role in diagnosis and clinical management. Lexical retrieval is a multiple-component process, and impairment to each of the components of this process gives rise to a different pattern of deficit. However, most current research on lexical retrieval in PPA categorizes deficits only broadly as either semantic or phonological, without identifying the exact functional locus of impairment or accounting for finer dissociations within these broad classifications.

 Aims

The current study applies a cognitive neuropsychological model of lexical retrieval and a corresponding classification framework to systematically categorize lexical retrieval impairments in 40 Hebrew-speakers with PPA.

 Methods

We used a comprehensive assessment battery that includes picture-naming, word-picture matching, picture association, and nonword repetition, and conducted a detailed error analysis. The classification algorithm considers success rate in tasks compared to age-matched norms and error types for each participant.

 Results

We identified lexical retrieval impairments in 75% of the participants. Selective impairments were found in each of the five cognitive components involved in lexical retrieval, with some participants diagnosed with more than one impaired component. The impaired components include the conceptual system (5 participants), the semantic lexicon (13 participants), the phonological output lexicon or the connection between semantic and phonological lexicons (18 participants), and the phonological output buffer (19 participants). Each impairment was associated with a distinct pattern of errors in both naming and in the additional language assessments. The findings reveal dissociations between different types of lexical retrieval impairments, reflecting the modular nature of lexical retrieval.

 Conclusions

Lexical retrieval deficits in PPA are prevalent and diverse. Capturing this diversity requires a componential, theory-driven model and classification framework. This framework more accurately describes the functional locus of impairment compared to the variant-based classification and allows for patients to be diagnosed with more than one type of impairment. Accurate diagnosis and classification are essential for effective treatment and the development of communication strategies for patients with PPA.

יישר כח!