Abnormalities of connected speech in semantic dementia vs Alzheimer's disease

Abstract

Background: Neurodegenerative syndromes are associated with varying degrees of language impairment. Connected speech analysis provides the most realistic measure of language function but its use has been restricted by operational constraints. Aims: In this prospective study we assessed the relative utility of a picture description task and a semi-structured interview in exposing the language decline in semantic dementia (SD) and typical mild Alzheimer's disease (AD), compared to each other and to healthy volunteers. Methods & Procedures:Our cohort comprised 16 patients with a clinical diagnosis of SD, 20 with mild typical AD, and 30 healthy participants. All speech samples were recorded during a face-to-face interview and were subjected to a well-controlled quantitative analysis.Outcomes & Results: Our results suggest that (a) the picture description task is more sensitive to abnormalities in the semantic measures, whereas the interviews are better at exposing morpho-syntactic deficits; (b) circumlocution is not, as has sometimes been claimed, a salient feature of speech in SD; (c) increases in the frequency of hesitation markers and of phonological and syntactic errors are prominent features of language decline in mild AD; and (d) a 150-word interview sample is adequate to provide a realistic reflection of language impairment. Conclusions: This study compared, for the first time, the two most commonly used methods of eliciting connected speech and documented many similarities in results from the two but also some salient differences in their sensitivity to specific aspects of language deficit. In addition, although replicating some aspects such as anomia, of what is already known about the language impairments in these two conditions, the study provides novel findings for both that could help clinicians in syndromic classification of anomic speech.

Connected Speech in Neurodegenerative Language Disorders: A Review

“…Other features in this domain have been rarely or inconsistently reported across studies; see Supplementary Table 3 for a complete list. Although, several studies agree in considering syntactic processes preserved in persons with AD (Kavé and Levy, 2003; Forbes-McKay and Venneri, 2005), a consistent number of the studies included in this review report a simplification of syntax, characterized by reduced sentences and short utterances (Ash et al, 2007; de Lira et al, 2011; Sajjadi et al, 2012a; Orimaye et al, 2014; Ash and Grossman, 2015; Yancheva et al, 2015). …”

“…The picture description task is reported as more suitable in detecting lexico-semantic disorders, while the semi-structure interview was more sensitive in revealing impairment affecting the morphological, syntactic, and discourse levels (Sajjadi et al, 2012a,b). A third study however reported that the story narration and the picture description can be used interchangeably (Ash et al, 2013).…”

Linguistic Features Identify Alzheimer’s Disease in Narrative Speech

“…Some researchers have reported syntactic impairments in AD, while others claim that any apparent deficits are in fact due to difficulties with memory and semantics [18]. Several studies have found evidence for a decrease in the syntactic complexity of language in AD [34][35][36]. Croisile et al [34] compared oral and written picture descriptions from 22 AD patients and matched controls, and found that the AD patients produced fewer subordinate clauses than controls.…”

Bilingual language intrusions and other speech errors in Alzheimer’s disease

“…For example, picture description reveals semantic impairments (as in Kavé & Levy, 2003), but free speech produced during a semi-structured interview may be better suited for exposing morphosyntactic processing deficits (Sajjadi, Patterson, Tomek, & Nestor, 2012). Although a large number of studies have attempted to characterize linguistic impairments in AD, relatively few have considered if and how speech errors might be elicited as a possible diagnostic tool.…”