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Primary progressive aphasia (PPA) is a gradually worsening disorder of speech with an insidious onset. It was first described by Marsel Mesulam in 1982.
There is considerable controversy over the nosology of this disorder. Clinical and pathological overlap have led it to being considered as part of the frontotemporal lobar degeneration (FTLD) spectrum of disorders. In the classical Mesulam criteria for PPA there are 2 variants: a non-fluent type (progressive non-fluent aphasia or PNFA) and a fluent aphasia. However, recent work has suggested that the underlying cognitive impairment in patients with progressive fluent aphasias is loss of semantic knowledge (semantic dementia or SD).  In the consensus criteria for FTLD described by Neary et al in 1989, PNFA and SD are the two classifications used.
According to Science Daily, in 2007, Northwestern University researchers discovered a link between higher rates of PPA dementia in men who had had vasectomies. Researchers theorize that this correlational observation may be due to increased antibody production related to the surgery. During the surgery, the protective barrier preventing sperm from mixing with the bloodstream is broken, causing the body to produce anti-sperm antibodies in 60 to 70 percent of men. However, researchers admit that more studies are needed and do not want to recommend that men abstain from vasectomy surgery because of the statistical correlation.
The San Francisco group have recently suggested that there is a third variant of PPA (so-called logopaenic PPA - Gorno-Tempini et al, 2004). However, there are limited descriptions of this disorder in the medical literature and early reports suggest that it is an atypical form of Alzheimer's disease rather than a disease falling into the frontotemporal lobar degeneration spectrum.
- Mesulam, MM (2001) "Primary progressive aphasia" Ann Neurol. 49(4):425-32.
- Gorno-Tempini ML, Dronkers NF, Rankin KP, Ogar JM, Phengrasamy L, Rosen HJ, Johnson JK, Weiner MW, Miller BL. (2004) "Cognition and anatomy in three variants of primary progressive aphasia." Ann Neurol. 55(3):335-46.
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