Syntactic Complexity as a Linguistic Marker to Differentiate Mild Cognitive Impairment From Normal Aging

Abstract

Purpose In this study, we sought to identify critical linguistic markers that can differentiate sentence processing of individuals with mild cognitive impairment (MCI) from the sentence processing of normal-aging populations by manipulating sentences' linguistic complexity. We investigated whether passive sentences, as linguistically complex structures, can serve as linguistic markers that can contribute to diagnoses that distinguish MCI from normal aging. Method In total, 52 participants, including 26 adults with amnestic MCI and 26 cognitively unimpaired adults, participated in the study. All participants were native speakers of Korean. We administered the two subsets of active and passive conditions using a sentence–picture paradigm with semantically reversible sentences to both groups. Results A mixed-effects model using PROC NLMIXED demonstrated that the MCI group exhibited differentially greater difficulty in processing passive than active sentences compared to the normal-aging group. A logistic regression fitted with the PROC LOGISTIC model identified the sum of the passive sentences, with age and education effects as the best models to distinguish individuals with MCI from the normal-aging group. Conclusion Sentence comprehension deficits emerged in the MCI stage when the syntactic complexity was increased. Furthermore, a passive structure was the best predictor for efficiently distinguishing the MCI group from the normal-aging group. These results are clinically and theoretically important, given that linguistic complexity can serve as a critical behavioral marker in the detection of early symptoms associated with linguistic–cognitive decline.

Age and Education Effects on a Novel Syntactic Assessment Battery for Elderly Adults

“…As delineated in the methods on the passivization process of Korean, the NP movement occurs from its original place as in the object position to the subject position in its surface structure, although the thematic role of the moved NP represents a theme, which is not canonically placed in a subject position. Sung et al (2020) confirmed that individuals with MCI behaviorally demonstrated greater difficulties in the syntactic structures that are claimed to be theoretically more complex. Furthermore, the authors tested the models to elicit the most efficient combination of the subtests among three models: (1) only active sentences, (2) only passive sentences, and (3) both active and passive sentences.…”

“…Furthermore, the current test has been validated through a series of the preliminary studies by Sung and colleagues by comparing young and old groups (Sung, 2015a,b;Sung et al, 2017). A most recent research on the SAB suggested that the syntactic complexity serves as a critical linguistic marker for differential diagnosis of mild cognitive impairment (MCI) from normal aging populations (Sung et al, 2020). The authors reported that individuals with MCI did not significantly differ from normal elderly adults in a simple active syntactic form, whereas they performed significantly worse on the passive sentences, which are linguistically more complex and challenging to process than active sentences.…”

“…The syntactic complexity has been reported as one of the critical factors that need to be considered when developing a theoretically motivated linguistic measure (Thompson et al, 2003). We specifically focused on the syntactic complexity from the perspectives of the syntactic computations (e.g., active vs. passive comparisons) and sentence length (e.g., active with 2place vs. 3-place verbs) Most recently, we reported the clinical utility for differential diagnosis of mild cognitive impairment (MCI) (Sung et al, 2020). They reported that the syntactic computational loads served as a critical linguistic marker to differentiate people with MCI from normal aging, when the fully semantically reversible structures were used by minimizing the top-down reliance.…”

Speech Performance among Healthy Malay Female Speakers during Dual Tasks and Sentence Complexity

“…Sentence complexity could also affect speech performance in various disorders, such as stuttering, and in those with degrading capacities, such as in the elderly population [30]. Individuals with mild cognitive impairment experienced greater difficulties in processing passive structures of sentence comprehension compared to those in the unimpaired cognitive group [33]. The morphosyntax of Malay lan-guage is predominantly derivational and it is characterized by an interchangeable mix of lexical and grammatical elements.…”

“…Current research in speech production and its disorders has mainly focused on speech and language separately [35]. Although previous studies have confirmed that linguistic factors affect speech motor coordination [31][32][33], relatively few investigators have examined how language demands may influence the production of speech, especially using a dual-task paradigm. To our knowledge, none of these studies have been conducted among Malay speakers, making it an issue when diagnosing a clinical population.…”