Semi-spontaneous language production in Dutch-speaking individuals with primary progressive aphasia

Primary progressive aphasia (PPA) is a neurodegenerative syndrome characterized by prominent language symptoms. Distinguishing between PPA variants, particularly non-fluent and logopenic variants, remains challenging. Language production is a crucial aspect of diagnosing PPA, with confrontation naming tests being commonly used. However, there are limitations to the use of confrontation naming alone and it is still unclear how confrontation naming relates to (semi-)spontaneous language production. Additionally, most studies have focused on English-speaking patients. This bias hinders a thorough understanding of PPA, as symptoms may vary across languages. In a pre-registered study, 49 Dutch-speaking individuals with PPA and 21 controls completed confrontation naming and a picture description task, from which we derived nine linguistic variables. The percentage of nouns was the only linguistic variable differentiating between the non-fluent and logopenic variants, highlighting the challenge of distinguishing these variants, also in a language other than English. We found a moderate correlation between confrontation naming and the frequency of nouns produced semi-spontaneously for the logopenic variant only. Together, these findings underscore the relevance of semi-spontaneous language production as a complement to confrontation naming for a more complete understanding of production abilities in PPA.