Citations

AbstractBackgroundApolipoprotein E ε4 (APOE ε4) is a risk factor for β‐amyloid deposition in Alzheimer's disease dementia. Its influence on β‐amyloid deposition in speech and language disorders, including primary progressive aphasia (PPA), is unclear.MethodsOne hundred thirty subjects with PPA or progressive speech apraxia underwent APOE genotyping and Pittsburgh compound B (PiB) PET scanning. The relationship between APOE ε4 and PiB status, as well as severity and regional distribution of PiB, was assessed.ResultsForty‐five subjects had an APOE ε4 allele and 60 subjects were PiB‐positive. The odds ratio for a subject with APOE ε4 being PiB‐positive compared with a subject without APOE ε4 being PiB‐positive was 10.2 (95% confidence interval, 4.4–25.5; P < .0001). The APOE ε4 allele did not influence regional PiB distribution or severity.ConclusionAPOE ε4 increases the risk of β‐amyloid deposition in PPA and progressive speech apraxia but does not influence regional β‐amyloid distribution or severity.

Background and purposeA subset of patients with Alzheimer's disease (AD) present with early and prominent language deficits. It is unclear whether the burden of underlying β‐amyloid pathology is associated with language or general cognitive impairment in these subjects.MethodsThe relationship between cortical β‐amyloid burden on [11C]Pittsburgh compound B (PiB) positron emission tomography (PET) and performance on the Montreal Cognitive Assessment (MoCA), the Wechsler Memory Scale − Third Edition (WMS‐III), the Boston Naming Test (BNT) and the Western Aphasia Battery (WAB) was assessed using regression and correlation analyses in subjects presenting with aphasia who showed β‐amyloid deposition on PiB PET.ResultsThe global PiB ratio was inversely correlated with MoCA (P = 0.02) and the WMS‐III Visual Reproduction (VR) subtest (VR I, P = 0.02; VR II, P = 0.04). However, the correlations between PiB ratio, BNT (P = 0.13), WAB aphasia quotient (P = 0.11) and WAB repetition scores (P = 0.34) were not significant.ConclusionThis study demonstrates that an increased cortical β‐amyloid burden is associated with cognitive impairment, but not language deficits, in AD subjects presenting with aphasia. The results suggest that β‐amyloid deposition could be partly contributing to impaired cognition in such patients whilst language dysfunction may be more influenced by other pathological mechanisms, perhaps downstream pathways of β‐amyloid deposition.

A good clinical understanding of the neurologic substrates of neurologic communicative disorders is important both to diagnosis and treatment. This article briefly reviews neurologic substrates for motor speech disorders (MSD) and how clinicians may identify neurologic signs and symptoms to facilitate differential diagnosis of apraxia of speech (AOS) and the various types of dysarthria. Students and clinicians have numerous resources regarding general neuroanatomy and neurophysiology (e.g. Benarroch, 2006; Kandel, Schwartz, and Jessel, 1991; Nolte, 2002; Snell, 1997) as well as neuroanatomic correlates of speech-language behavior and disorders (Bhatnagar, 2012; Duffy, 2013). Articles on aspects of neuroimaging (Brown, Petersen and Schlaggar, 2003; Shuster, 2003) and neurologic substrates for MSDs (Farinella-Bocian, Strand, and Benarroch, 2007) are also available in previous editions of Perspectives. This article begins with an overview of the differing MSDs. A brief overview of neurologic systems is provided, followed by a more detailed description of the neurologic substrates for MSDs. Examples of clinical observations of speech and non-speech characteristics that can aid the clinician in understanding the underlying neural deficit are provided.