Objective: To characterize and compare the neuropsychological profiles of patients with primary progressive apraxia of speech (PPAOS) and apraxia of speech with progressive agrammatic aphasia (AOS-PAA).
Method: Thirty-nine patients with PPAOS and 49 patients with AOS-PAA underwent formal neurological, speech, language, and neuropsychological evaluations. Cognitive domains assessed included immediate and delayed episodic memory (Wechsler Memory Scale-Third edition; Logical Memory; Visual Reproduction; Rey Auditory Verbal Learning Test), processing speed (Trail Making Test A), executive functioning (Trail Making Test B; Delis-Kaplan Executive Functioning Scale - Sorting), and visuospatial ability (Rey-Osterrieth Complex Figure copy).
Results: The PPAOS patients were cognitively average or higher in the domains of immediate and delayed episodic memory, processing speed, executive functioning, and visuospatial ability. Patients with AOS-PAA performed more poorly on tests of immediate and delayed episodic memory and executive functioning compared to those with PPAOS. For every 1 unit increase in aphasia severity (e.g. mild to moderate), performance declined by 1/3 to 1/2 a standard deviation depending on cognitive domain. The degree of decline was stronger within the more verbally mediated domains, but was also notable in less verbally mediated domains.
Conclusion: The study provides neuropsychological evidence further supporting the distinction of PPAOS from primary progressive aphasia and should be used to inform future diagnostic criteria. More immediately, it informs prognostication and treatment planning.
Keywords: Agrammatic aphasia; Frontotemporal dementia; Motor speech disorder; Nonfluent primary progressive aphasia; Primary progressive aphasia; Primary progressive apraxia of speech.