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What is Progressive nonfluent aphasia (PNFA)?
Progressive nonfluent aphasia and semantic dementia disorders are characterized under the rubric of primary progressive aphasia and are considered in the family of FTLD.
They involve the gradual and relatively isolated dissolution of language function.
Language impairment is usually the only factor that compromises ADLs for at least the first 2 years of the disease, but difficulties eventually progress to include other cognitive domains.
Progressive nonfluent aphasia and semantic dementia are more commonly seen as variants of frontotemporal dementia, and less commonly in AD or Creutzfeld–Jakob disease (CJD).
The PNFA variant of primary progressive aphasia presents as a progressive disorder of expressive language.
There is effortful speech production, phonologic and grammatical errors, and word retrieval difficulties.
These persons are clinically similar to persons with Broca’s aphasia, except that the onset is not abrupt as it would be when Broca’s is due to stroke.
There may be associated acalculia or ideomotor apraxia. Some patients with PNFA develop Parkinson-like motor changes.
Twenty percent are associated with tauopathies, 60% are ubiquitinopathies, and 20% are due to AD. Rarely, it can be the presenting feature of CJD.
What is semantic dementia(SD)?
The semantic dementia variant of primary progressive aphasia is characterized by a severe naming and word comprehension impairment in the context of fluent, effortless, and grammatical speech output as well as the gradual deterioration of knowledge about the world. Overall, speech output in SD is most similar to Wernicke’s aphasia.
The person can speak but has lost the connection of words to meaning. If patients cannot think of a word with a certain meaning, they may substitute related words from the same category—for example, eventually calling all animals “dog.”
They also lose information about other aspects of things, such as the use, color, and detailed appearance of objects.
This loss of meaning for both verbal and nonverbal concepts (semantics) contrasts with the preservation of visuospatial skills and day-to-day memory.
The predominant pathologic finding in SD is ubiquitinated inclusions.
The logopenic variant refers to the combination of features of both PPA and SD. This syndrome may be associated with Alzheimer’s pathology.
Logopenic progressive aphasia (LPA) is characterized by impaired repetition and naming difficulty. In contrast to semantic dementia, where naming is impaired and word meaning is lost, in LPA the naming deficit is due to a retrieval deficit.
Patients may experience a loss of fluency and comprehension of single words, although comprehension of objects is preserved.
