Gorno (2004). Cognition and anatomy in three variants of primary progressive aphasia.
The first symptoms of focal forms of neurodegenerative diseases:
- Particularly of frontotemporal lobar degeneration (FTLD) and cortico-basal degeneration
(CBD) are isolated speech and language difficulties.
- Alzheimer’s disease (AD) patients present with atypical focal cognitive manifestations, including
fluent and non-fluent progressive aphasia.
Primary progressive aphasia (PPA) = when speech and language deficits remain the only complaint
for at least 2 years. The most frequent finding in PPA is an FTLD-type of damage, such as dementia
lacking distinctive pathology (DHLDH) or Pick’s disease. Isolated speech and language deficits in PPA
correspond to a mainly left hemisphere anatomical involvement. In a comparison between PPA
patients and normal controls, atrophy was found in the left superior temporal gyrus and inferior
parietal lobe. There are three variants -> semantic, non-fluent and logopenic PPA.
Non-fluent progressive aphasia (NFPA) or “PPA with agrammatism” = labored speech,
agrammatism in production, and/or comprehension, variable degrees of anomia, and phonemic
paraphasia’s, in the presence of relatively preserved word comprehension. In the non-fluent clinical
variant of PPA studies have shown left frontal hypometabolism.
Sematic dementia (SD) or “fluent progressive aphasia” = fluent, grammatically correct speech, loss
of word and object meaning, surface dyslexia, and relatively preserved syntactic comprehension skills.
Clinical criteria for FTLD = include NFPA and SD as two possible clinical presentations of FTLD.
“PPA-plus” syndrome = SD has been included in the PPA spectrum.
Progressive aphemia or anarthria = patients show mainly a severe speech disorder.
Logopenic variant PPA = word-finding difficulties and decreased output, but relatively preserved
syntax and phonology.
PPA with comprehension (verbal semantics) deficits = fluent speech and anomia but not the
multimodal semantic deficits typical of SD.
Current study -> performed a VBM analysis in a neurologically, cognitively, and genetically well-
characterized cohort of 31 PPA patients to identify the overall network of brain regions involved in
PPA, and the specific patterns of atrophy associated with each PPA clinical variant.
Cognitive testing -> different tests were used:
- Neuropsychological screening battery
- Speech and language evaluation -> speech and language production, lexical retrieval and semantic
memory, syntactic comprehension and reading skills.
- Primary progressive aphasia subgroup classification:
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, o NFPA -> non-fluent speech output, labored articulation, agrammatism, difficulty with
comprehension of complex syntactic structures, word-finding deficits, and preserved single-
word comprehension.
o SD -> patients with fluent, grammatical speech, confrontation naming deficits, semantic
deficits for words and, initially less severely for objects, surface dyslexia, and relatively spared
syntactic comprehension.
Results -> cognitive data -> speech and language performance:
- Non-fluent progressive aphasia
o NFPA group scored lowest in the fluency task. The major reason for dysfluency was apraxia
of speech (patients also showed mild dysarthria).
o Single-word comprehension was unimpaired, confrontation naming was at the 50th
percentile (with good recognition on the unnamed items), semantic comprehension was
impaired only for the most complex structures, and performance on the “sequential
commands” was within normal limits.
o The NFPA group performed below the first percentile in the single-word reading task.
Errors were equally distributed between regular and irregular words.
- Semantic dementia
o The group did not differ significantly from controls on the “picture description task”. Speech
was normal in rate, well-articulated, and grammatically correct. Word and sentence
repetition were spared.
o SD patient showed a significant overall deficit in single-word comprehension, particularly
for shaped, whereas comprehension for color names was relatively spared.
o The SD group showed the worst performance on the 60-item BNT, along with severely
impaired scores on BNT recognition and on the semantic association test. SD performed
within normal limits in the comprehension of even the most complex syntactic structures.
o SD patients had greater difficulty reading irregular than regular words.
- Logopenic progressive aphasia
o Patients showed a pattern of speech output that has been defined as “logopenic”, which is
slow, made of syntactically simple but correct sentences, with frequent word-finding pauses.
o The logopenic group had generalized difficulty on syntactic comprehension tasks, and,
unlike the SD and NFPA groups, LPA were significantly impaired in all but the simple
subtests. Repetition also was significantly impaired compared with controls.
o Single-word comprehension and semantic association abilities were within normal limits.
Results -> cognitive data -> general neuropsychological performance -> all groups were significantly
impaired compared with controls on word-generation tasks, verbal immediate recall, and verbally
mediated executive tasks. CDR scores were significantly lower in each patient compared with controls.
- Non-fluent progressive aphasia
o The NFPA group performed significantly better on verbal memory tasks than the other two
patient groups, although their scores were still lower than controls.
o The NFPA group performed within normal limits on MMSE and short BNT.
o They also showed the worst performance on the praxis test.
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