Chapter 5 - Primary progressive aphasias

Abstract

There are three different variants of primary progressive aphasia (PPA): nonfluent PPA (nfPPA), semantic dementia (SD), and logopenic PPA (lPPA). Patients with nfPPA display (subtle) disorder (dysarthria, apraxia of speech, effortful speech) and slow speech, impairments in phonological word fluency and in copying task, as long as they include a planning component. Patients with SD are characterized by problems understanding single words. They may also exhibit visual agnosia being unable to identify pictures. Their copying and recognition performance, however, may be almost perfect. The lPPA variant is characterized by word-finding problems but otherwise fluent speech. These patients show severe impairments in verbal working memory (digit span forward as measure of the phonological store) and mild impairments in verbal recognition tasks. Assessment of PPA should entail a free description of a standardized picture to get a clinical impression of spontaneous speech. Moreover the results from the word fluency tests of the Consortium to Establish a Registry for Alzheimer’s Disease, Neuropsychological Assessment Battery (CERAD-NAB), the language comprehension and digit span forward should be inspected. Reading and writing skills are helpful for the differential diagnosis: patients with SD show surface dyslexia and dysgraphia, whereas patients with lPPA and nfPPA might display phonological dyslexia. nfPPA and lPPA may be treated by facilitation strategies using semantic, phonologic, or action-related facilitation cues. A recent study combining word facilitation training and transcranial direct current stimulation (tDCS) revealed that the progress of lPPA and nfPPA may be delayed by such a treatment. SD patients did not benefit from that approach, however, this could have been due to the specific protocol for the tDCS intervention (not stimulating the primary brain regions affected in SD). In the case of nfPPA patients, script training might be tried out to improve speech and word finding. Up to now, there are no convincing treatment studies for SD patients.