Grammatical comprehension deficits in non-fluent/agrammatic primary progressive aphasia

Abstract

Importance Grammatical comprehension difficulty is an essential supporting feature of the non-fluent/agrammatic variant of primary progressive aphasia (naPPA), but well-controlled clinical measures of grammatical comprehension are unavailable. Objective To develop a measure of grammatical comprehension and examine this comparatively in PPA variants and behavioural-variant frontotemporal degeneration (bvFTD) and to assess the neuroanatomic basis for these deficits with volumetric grey matter atrophy and whole-brain fractional anisotropy (FA) in white matter tracts. Design Case–control study. Setting Academic medical centre. Participants 39 patients with variants of PPA (naPPA=12, lvPPA=15 and svPPA=12), 27 bvFTD patients without aphasia and 12 healthy controls. Main outcome measure Grammatical comprehension accuracy. Results Patients with naPPA had selective difficulty understanding cleft sentence structures, while all PPA variants and patients with bvFTD were impaired with sentences containing a centre-embedded subordinate clause. Patients with bvFTD were also impaired understanding sentences involving short-term memory. Linear regressions related grammatical comprehension difficulty in naPPA to left anterior-superior temporal atrophy and reduced FA in corpus callosum and inferior frontal-occipital fasciculus. Difficulty with centre-embedded sentences in other PPA variants was related to other brain regions. Conclusions and relevance These findings emphasise a distinct grammatical comprehension deficit in naPPA and associate this with interruption of a frontal-temporal neural network.

Linguistic Aspects of Primary Progressive Aphasia

“…This deficit at the single-word level understandably has a significant impact on sentences as well. Patients with svPPA thus appear to be impaired on tasks that involve sentence comprehension (Charles et al 2014) and sentence expression (Ash et al 2013). …”

“…In a sentence like ‘Boys that girls kick are unfriendly,’ for example, naPPA patients often err when asked, ‘Who did the kicking?’ (Peelle et al 2008). These patients also have difficulty pointing to one of two pictures based on a sentence, where selecting the correct picture depends on appreciating the sentence’s grammatical structure (Charles et al 2014, Wilson et al 2010a). Another study used an anagram task to show that patients with naPPA have difficulty ordering words printed on cards into a grammatically complex question about a picture (Weintraub et al 2009).…”

“…Another study used an anagram task to show that patients with naPPA have difficulty ordering words printed on cards into a grammatically complex question about a picture (Weintraub et al 2009). Grammatical difficulties such as these may help distinguish naPPA from other PPA variants (Charles et al 2014, Mesulam et al 2012, Peelle et al 2008). However, investigators must take care, as comprehension of center-embedded subordinate phrase constructions is broadly impaired across all PPA variants: These sentences are long and typically involve multiple propositions, and thus are sensitive to processing resources such as limited auditory–verbal short-term memory and working memory that may be compromised in other aphasic and nonaphasic variants of frontotemporal degeneration such as lvPPA and bvFTD.…”

“…However, investigators must take care, as comprehension of center-embedded subordinate phrase constructions is broadly impaired across all PPA variants: These sentences are long and typically involve multiple propositions, and thus are sensitive to processing resources such as limited auditory–verbal short-term memory and working memory that may be compromised in other aphasic and nonaphasic variants of frontotemporal degeneration such as lvPPA and bvFTD. Cleft sentences are more likely to be selectively impaired in naPPA and are not significantly impaired in other patient groups, possibly because they are less confounded by greater length and larger number of propositions (Charles et al 2014). Although nonspecific cognitive difficulty may contribute to comprehension impairments, a correlation between nonspecific measures of dementia, such as the Mini–Mental State Exam (MMSE), and comprehension performance is typically not found in naPPA.…”

Pitch Variations amongst Mild and Moderate Mentally Impaired Person

“…I relates to a person's ability to utter words. One takes many pauses [7] and lots of time to utter words. Though their comprehension is surprisingly good but their omission of words makes it really hard to understand.…”