Declines in Connected Language Are Associated with Very Early Mild Cognitive Impairment: Results from the Wisconsin Registry for Alzheimer's Prevention.

Kimberly D Mueller,Lyn S Turkstra,Bruce P Hermann,Sterling C Johnson,Rebecca L Koscik

doi:10.3389/fnagi.2017.00437

Abstract

Changes to everyday spoken language (“connected language”) are evident in persons with AD dementia, yet little is known about when these changes are first detectable on the continuum of cognitive decline. The aim of this study was to determine if participants with very early, subclinical memory declines were also showing declines in connected language. We analyzed connected language samples obtained from a simple picture description task at two time points in 264 participants from the Wisconsin Registry for Alzheimer’s Prevention (WRAP). In parallel, participants were classified as either “Cognitively Healthy” or “Early Mild Cognitive Impairment” based on longitudinal neuropsychological test performance. Linear mixed effects models were used to analyze language parameters that were extracted from the connected language samples using automated feature extraction. Participants with eMCI status declined faster in features of speech fluency and semantic content than those who were cognitively stable. Measures of lexical diversity and grammatical complexity were not associated with eMCI status in this group. These findings provide novel insights about the relationship between cognitive decline and everyday language, using a quick, inexpensive, and performance-based method.

Highlights

There have been significant advances in detecting neuropathological changes early in the Alzheimer’s disease (AD) continuum, and these have spurred the development of multiple clinical trials, investigating both pharmacological and non-pharmacological early interventions
At the visit with the second speech sample, there were 64 participants classified as early Mild Cognitive Impairment (eMCI) and 200 as CN; 47 of the 64 eMCI participants were eMCI at the first speech sample
The eMCI group was comprised of significantly more males (54%) and they were slightly older

Summary

Introduction

There have been significant advances in detecting neuropathological changes early in the Alzheimer’s disease (AD) continuum, and these have spurred the development of multiple clinical trials, investigating both pharmacological and non-pharmacological early interventions. One candidate tool is analysis of connected language in discourse, which has shown to be an informative measure of language problems across mild to moderate stages on the AD continuum (Nicholas et al, 1985; Bayles et al, 1992; Tomoeda and Bayles, 1993). Few studies have examined the earliest point at which connected language changes are observable [i.e., the Mild Cognitive Impairment (MCI) phase or before], and the literature that exists has significant limitations. Longitudinal data are important because both discourse features and the clinical expression of MCI and AD are heterogeneous (Duong et al, 2005), so measurement of within-person change over time is critical for characterizing change. There is a need for both studies of connected language in persons with early cognitive decline, and studies that examine performance over time

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