Introduction 

Prior evidence from many languages suggests that reference to past events is more difficult to comprehend and more vulnerable to impairment in people with agrammatic stroke aphasia. We examined verbal time reference in three major variants of primary progressive aphasia (PPA): agrammatic, logopenic, and semantic variants.

Methods 

Participants completed a visual world eye-tracking task of sentence comprehension. The task comprised 20 action photos, each in a past or present reference form. Participants listened to a sentence as they viewed an array of two action photos.

Results 

Results from the eye data indicate that all PPA groups fixated on the target picture less than healthy controls for past time reference. This pattern also was found for present time reference in the logopenic and semantic, but not the agrammatic, groups. The agrammatic group also showed delayed looks to the target picture, but only for past time reference. These results are consistent with prior findings for agrammatic participants suggesting a grammatical deficit that impacts comprehension of past time reference. The results from the logopenic and semantic groups suggest a lexical deficit that affects verb comprehension, but not specifically comprehension of past time reference. 

Conclusions  

Our study implicates that grammatical impairment in past time reference is an important feature for language assessment of PPA.

References

Bastiaanse, R., et al. (2011).  Time reference in agrammatic aphasia: a cross-linguistic study. Journal of Neurolinguistics, 24(6).

Thompson, C., et al. (2012). Dissociations between fluency and agrammatism in primary progressive aphasia. Aphasiology, 26(1).