Disintegration at the Syntax-Semantics Interface in Prodromal Alzheimer's Disease: New Evidence from Complex Sentence Anaphora in Amnestic Mild Cognitive Impairment (aMCI).

Although diverse language deficits have been widely observed in prodromal Alzheimer's disease (AD), the underlying nature of such deficits and their explanation remains opaque. Consequently, both clinical applications and brain-language models are not well-defined. In this paper we report results from two experiments which test language production in a group of individuals with amnestic Mild Cognitive Impairment (aMCI) in contrast to healthy aging and healthy young. The experiments apply factorial designs informed by linguistic analysis to test two forms of complex sentences involving anaphora (relations between pronouns and their antecedents). Results show that aMCI individuals differentiate forms of anaphora depending on sentence structure, with selective impairment of sentences which involve construal with reference to context (anaphoric coreference). We argue that aMCI individuals maintain core structural knowledge while evidencing deficiency in syntax-semantics integration, thus locating the source of the deficit in the language-thought interface of the Language Faculty.

Language Decline Characterizes Amnestic Mild Cognitive Impairment Independent of Cognitive Decline.

Purpose This research investigated the nature of cognitive decline in prodromal Alzheimer's disease (AD), particularly in mild cognitive impairment, amnestic type (aMCI). We assessed language in aMCI as compared with healthy aging (HA) and healthy young (HY) with new psycholinguistic assessment of complex sentences, and we tested the degree to which deficits on this language measure relate to performance in other general cognitive domains such as memory. Method Sixty-one individuals with aMCI were compared with 24 HA and 10 HY adults on a psycholinguistic measure of complex sentence production (relative clauses). In addition, HA, HY, and a subset of the aMCI participants (n = 22) were also tested on a multidomain cognitive screen, the Addenbrooke's Cognitive Examination-Revised (ACE-R), and on a verbal working memory Brown-Peterson (BP) test. General and generalized linear mixed models were used to test psycholinguistic results and to test whether ACE-R and BP performance predicted performance on the psycholinguistic test similarly in the aMCI and HA groups. Results On the psycholinguistic measure, sentence imitation was significantly deficited in aMCI in comparison with that in HA and HY. Experimental factorial designs revealed that individuals with aMCI had particular difficulty repeating sentences that especially challenged syntax-semantics integration. As expected, the aMCI group also performed significantly below the HY and HA groups on the ACE-R. Neither the ACE-R Memory subtest nor the BP total scores predicted performance on the psycholinguistic task for either the aMCI or the HA group. However, the ACE-R total score significantly predicted psycholinguistic task performance, with increased ACE-R performance predicting increased psycholinguistic task performance only for the HA group, not for the aMCI group. Conclusions Results suggest a selective deterioration in language in aMCI, specifically a weakening of syntax-semantics integration in complex sentence processing, and a general independence of this language deficit and memory decline. Results cohere with previous assessments of the nature of difficulty in complex sentence formation in aMCI. We argue that clinical screening for prodromal AD can be strengthened by supplementary testing of language, as well as memory, and extended evaluation of strength of their relation.

Reversing Ribot: does regression hold in language of prodromal Alzheimer's disease?

We consider the regression or retrogenesis hypothesis, which argues that order of acquisition in development is reversed in neurodegeneration or pathology. Originally proposed as a regression hypothesis for the study of memory disorders, specifically retrograde amnesia, by Ribot (1881), it has been extended to the study of brain aging and pathology and to language. We investigate this hypothesis in a new study of language development, aging, and pathology. Through interuniversity collaboration using a matched experimental design and task, we compare production of complex sentences containing relative clauses by normal monolingual children during normal development, healthy young adults, healthy aging adults, and aging adults diagnosed with mild cognitive impairment, a recognized potential harbinger of Alzheimer's disease. Our results refute the regression hypothesis in this area and lead to potential syntactic markers for prodromal Alzheimer's disease and predictions for future brain imaging analyses.

Getting there faster: 18- and 24-month-old infants' use of function words to determine reference.

Infants of 18 and 24 months acquiring English were tested in a preferential looking task on their ability to detect ungrammaticalities caused by manipulating a single function word in sentences. Infants heard grammatical sentences in which the determiner the preceded a target noun, as well as three ungrammatical conditions in which the was either dropped, replaced by a nonsense function word (el), or replaced by an alternate English function word (and). Both the 18- and 24-month-old infants oriented faster and more accurately to a visual target following grammatical sentences. The results suggest that by 18 months of age, infants use their knowledge of determiners in sentence computation and in establishing reference.

Continuity and development in the acquisition of inversion in yes/no questions: dissociating movement and inflection.

This paper examines two- to five-year-old children's knowledge of inversion in English yes/no questions through a new experimental study. It challenges the view that the syntax for inversion develops slowly in child English and tests the hypothesis that grammatical competence for inversion is present from the earliest testable ages of the child's sentence production. The experimental design is based on the premise that a valid test of this hypothesis must dissociate from inversion various language-specific aspects of English grammar, including its inflectional system. An elicited imitation method was used to test parallel, lexically-matched declarative and question structures across several different verb types in a design which dissociated subject-auxiliary inversion from the English-specific realization of the inflectional/auxiliary system. Using this design, the results showed no significant difference in amount or type of children's errors between declarative (non-inverted) and question (inverted) sentences with modals or auxiliary be, but a significant difference for sentences with main verbs (requiring reconstruction of inflection through do-support) and copula be. The results from sentences with auxiliary be and those with modals indicate that knowledge of inversion is present throughout our very young sample and does not develop during this time. We argue that these results indicate that the grammar of inversion is present from the youngest ages tested. Our results also provide evidence of development relevant to the English-specific inflectional system. We conclude with a new developmental hypothesis: development in question formation occurs in integrating language-specific knowledge related to inflection with the principles of Universal Grammar which allow grammatical inversion.