Connected Language in Late Middle-Aged Adults at Risk for Alzheimer’s Disease

Article type: Research Article

Authors: Mueller, Kimberly Diggle^{a; e; *} | Koscik, Rebecca L.^a | Turkstra, Lyn S.^e | Riedeman, Sarah K.^e | LaRue, Asenath^a | Clark, Lindsay R.^{a; c} | Hermann, Bruce^{a; d} | Sager, Mark A.^a | Johnson, Sterling C.^{a; b; c}

Affiliations: [a] Wisconsin Alzheimer’s Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA | [b] Geriatric Research Education and Clinical Center, William S. Middleton Memorial VA Hospital, Madison WI, USA | [c] Wisconsin Alzheimer’s Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA | [d] Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA | [e] Department of Communication Sciences & Disorders, University of Wisconsin, Madison, WI, USA

Correspondence: [*] Correspondence to: Kimberly D. Mueller, MS, Wisconsin Alzheimer’s Institute, Wisconsin Alumni Research Foundation – 9th Floor, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA. Tel.: +1 608 829 3300; Fax: +1 608 829 3315; E-mail: kdmueller@wisc.edu.

Abstract: Connected language is often impaired among people with Alzheimer’s disease (AD), yet little is known about when language difficulties first emerge on the path to a clinical diagnosis. The objective of this study was to determine whether individuals with psychometric (preclinical) evidence of amnestic mild cognitive impairment (pMCI) showed deficits in connected language measures. Participants were 39 pMCI and 39 cognitively healthy (CH) adults drawn from the Wisconsin Registry for Alzheimer’s Prevention, who were matched for age, literacy, and sex. Participants completed a connected language task in which they described the Cookie Theft picture from the Boston Diagnostic Aphasia Examination. Language samples were analyzed across three language domains: content, syntactic complexity, and speech fluency. Paired t-tests were used to compare CH and pMCI groups on all variables, and Cohen’s d effect sizes were calculated for each comparison. The CH and pMCI groups differed significantly on measures of content (e.g., CH group produced more semantic units, more unique words and had larger idea density, on average, than the pMCI group). The picture description findings are consistent with previous retrospective studies showing semantic language differences in adults with autopsy-confirmed AD. Given that these comparisons are between cognitively healthy and pMCI individuals (before a clinical MCI diagnosis), these findings may represent subtle language difficulty in spontaneous speech, and may be predictive of larger language changes over time.

Keywords: Alzheimer’s disease, dementia, discourse, language disorders, linguistics, mild cognitive impairment, semantics, speech

DOI: 10.3233/JAD-160252

Journal: Journal of Alzheimer's Disease, vol. 54, no. 4, pp. 1539-1550, 2016