Discussion 2 Flashcards
Individual test scores failed to show?
a clear pattern of deficits in lvPPA relative to the nfvPPA group.
Impaired repetition is a central feature of ? And may be predicted?
LvPPA and may be predicated on phonological working memory impairment.
Performance on working memory tests was undoubtedly impaired in ?
And which measures in particular disriminated ? From ?
lvPPA relative to controls, and the Brown–Peterson measures, in particular, discriminated lvPPA from SD.
impairments on working memory tests were also apparent in the nfvPPA and AD groups and the specificity of these measures was generally low for?
LvPPA
another factor analytic study of PPA found that repetition clustered (ryhmittyä, kerääntyä) with
agrammatism and AOS, core features of nfvPPA.
Given the marked speech production problems exhibited by patients with nfvPPA, it was perhaps unsurprising that
they were impaired to a similar degree on tasks of verbal working memory as lvPPA patients. (nfvPPA patients)
Our study supports the supposition that,
in isolation, this feature has limited utility as a core diagnostic marker of lvPPA
the PCA elicited a ‘working memory’ factor which, together with a ‘speech production and grammaticality’ factor and a ‘semantics and behaviour’ factor, was able to
differentiate lvPPA patients from nfvPPA and SD patients relatively well when evaluated with a linear discriminant analysis.
Composite measures of working memory may therefore prove useful diagnostically in the classification of PPA.
Kyllä
The PCA analysis did not ?
distinguish lvPPA from multi-domain AD
The findings suggest that common language and working memory deficits occur in
lvPPA and multi- domain AD
Their findings ? From some previous studies?
findings differ from those of some previous studies, which have found differences between AD and lvPPA patients in the realm of verbal working memory and language.
Differences in findings might reflect phenotypic variation in study cohorts,
of which age is known to be one determinant. Differences in assessment methods might also be relevant. Stage of illness might also be relevant.
The finding by Foxe and Meyer of poorer phonological short-term memory in lvPPA were compared with
AD, despite patients being matched for visual short-term memory performance might represent a transient distinction. (lyhytaikainen eroavaisuus)
It is of interest in this regard that longitudinal studies of lvPPA have indicated
convergence (lähentyminen, kohdistuminen) over time with the clinical symptoms of AD and a spread of atrophy consistent with AD
It is possible that at an earlier stage of disease
greater differences might have been elicited between the two groups.
the majority of patients were assessed within a year of their medical referral, so were still at a relatively early stage of illness.
What further studies would be useful and involving what?
Further studies involving incident cases and longitudinal investigation of working memory in a spectrum of different AD subtypes with varying ages of onset would be useful.
Which factor was most useful in classifying the three patient groups?
The ‘grammaticality and speech production’ factor was the most useful factor in classifying the three patient groups.
What has been suggested of lvPPA features rather than?
The absence of frank impairments in grammar and comprehension should be a core feature of lvPPA, rather than impaired repetition
Our findings support the notion that grammaticality (together with speech production) is ? In differientation of PPA ?
is more effective than impaired repetition in differentiation of PPA. However, supporting criteria for lvPPA are almost exclusively made up of features denoting preserved areas of speech and language.
The only other core feature,?, is a notoriously common feature across dementia syndromes, in this study, proved non-discriminatory.
The only other core feature, impaired single word retrieval, is a notoriously common feature across dementia syndromes, in this study, proved non-discriminatory.
What do they suggest as a new way of criteria and denoting a disorder?
Thus, a change in the core criteria from ‘impaired phrase repetition’ to ‘preserved grammaticality and speech production’ would constitute denoting a disorder exclusively by absence of features, rather than the presence of characteristic features.
The likely effect of this would be that any patient with PPA who does not have the defining features of the other two subtypes would be classified as ?
LvPPA
While this would increase the sensitivity of the criteria for lvPPA, it would have a ?
detrimental (= harmful, damaging) effect on the specificity, as mild cases of nfvPPA and svPPA and atypical PPA patients would probably fulfil criteria for lvPPA.
What limitations this study has? FIRST?
Firstly, inevitably there is some circularity when evaluating classification of patients on the same areas of cognition that are used to reach a diagnosis. Nevertheless, clinical diagnoses were made independently by clinical history and observation and neurological examination, with supportive neuropsychological evaluation. Furthermore, most of the tests employed as part of this study are not routinely used in the clinic and some measures were purely experimental. Indeed, all patients with lvPPA exhibited impairments in sentence repetition during clinical diagnostic testing; yet, some patients performed at ceiling on the relatively undemanding PALPA sentence repetition task. The choice of the sentence repetition task might be criticized for being too easy. On the other hand, it did elicit impairments in the nfvPPA group sufficient to distinguish nfvPPA from SD. Sentence repetition is therefore unlikely to prove a useful diagnostic marker for lvPPA, to allow it to be distinguished from nvfPPA, irrespective of the level of difficulty of the repetition task. In addition, the individual-rotated factors elicited from the PCA included combinations of tests and behavioural measures that would not routinely be used in classification of patients.
Limitations of this study? SECOND?
Secondly, by necessity of the prospectivenatureofthestudy,thesamplesizewasrelativelysmall(n = 47).Thenumber of patients included in the PCA was smaller still (n = 33). However, as outlined in the methods, the ratio of participants to variables was acceptable. Nevertheless, future confirmatory studies with larger numbers of participants would be useful.
A third limitation?
A third limitation is that, due to the relatively small sample, in order to have a reasonable participant to variable ratio for the PCA, the study did not involve an exhaustive assessment of non-linguistic and linguistic factors. Cognitive domains were chosen owing to their theoretical importance in a study of progressive aphasia; yet, there are some notable omissions. One such factor is episodic memory, which has been found to be significantly impaired in AD relative to lvPPA and in lvPPA relative to nfvPPA. In this study, standard episodic memory measures were omitted on the grounds that performance may be compromised secondarily by problems in language and working memory. However, further studies including carefully selected episodic memory variables would be interesting, as would the inclusion of other behavioural domains such as emotion processing and more detailed evaluation of connected speech, which may be useful in differential diagnosis of PPA
A final limitation relates?
A final limitation relates to gender differences. The participants were consecutive referrals who met the selection criteria and agreed to participate. An unintended consequence was that the groups were not matched for gender. In future studies it would be important to consider the possible influence of gender on differential performance patterns.
IN CONCLUSION???
simple and brief tasks of sentence ordering, narrative production, buccofacial praxis, and single word comprehension are helpful in the discrimination of forms of PPA. Nevertheless, evaluating single tests in isolation has limitations. Namely, tests may lack sensitivity or specificity because they are too easy or because failure can arise for different underlying reasons. A test profile is important, as exemplified by the PCA. Characteristic profiles in PPA include non-language features, in particular, the presence of apraxia in nfvPPA, which extends beyond AOS, behavioural changes in SD, and working memory deficits in lvPPA. Notably, while factors elicited by the PCA were effective at differentiating nfvPPA, SD, and lvPPA, these measures were unable to differentiate lvPPA and multi-domain AD. The similarity in language profile in lvPPA and multidomain AD is important because it supports the contention that lvPPA is largely a focal, linguistic form of AD rather than FTLD. Nevertheless, lvPPA risks being a diagnosis of exclusion. The classification of forms of PPA that are distinct from nfvPPA and SD remains a challenge.
