Decreased striatal dopamine transporter uptake in the non-fluent/agrammatic variant of primary progressive aphasia

BACKGROUND AND PURPOSE

Patients with the non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) may develop atypical parkinsonian syndromes. However, there is no current biomarker to assess which patients are at high risk of developing parkinsonism. 123I-2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane (123I-FP-CIT)-SPECT detects striatal dopamine dysfunction in vivo. The objective of the present study was to study whether non-fluent/agrammatic patients without parkinsonism at baseline present decreased striatal 123I-FP-CIT uptake.

METHODS

Visual and semi-quantitative assessments of the striatal 123I-FP-CIT uptake ratio were carried out in 15 patients with nfvPPA, eight patients with the logopenic variant of PPA (lvPPA) and 18 controls. To rule out progranulin mutations or underlying Alzheimer's disease (AD), serum progranulin levels and cerebrospinal fluid (CSF) biomarkers of AD (Aβ42 , total-tau, phosphorylated-tau181 ) were determined. A second 123I-FP-CIT-SPECT analysis in the biomarker-enriched groups was also carried out.

RESULTS

Patients with nfvPPA presented reduced striatal 123I-FP-CIT binding, especially in the left hemisphere (P = 0.002), compared with controls. All lvPPA patients had normal striatal 123I-FP-CIT uptake. 123I-FP-CIT striatal binding in nfvPPA patients with normal progranulin and CSF biomarker levels (nfvPPA/bio-) was also significantly reduced (P < 0.05) compared with lvPPA patients with positive AD biomarkers. Sixty-four per cent (9/14) of nfvPPA patients and 80% of nfvPPA/bio- patients (8/10) showed a diminished individual left striatal 123I-FP-CIT uptake ratio. On follow-up, seven nfvPPA/bio- patients developed parkinsonism (median 1.9 years; range 1.2-2.9), six of them with baseline reduced 123I-FP-CIT uptake.

CONCLUSIONS

Reduced striatal tracer uptake in nfvPPA patients prior to clinical parkinsonism can be detected by 123I-FP-CIT-SPECT, especially in those with nfvPPA/bio-, suggesting subclinical nigrostriatal degeneration. Decreased striatal 123I-FP-CIT binding might identify PPA patients at increased risk of developing atypical parkinsonian syndromes, probably related to tau-pathology.

Language, executive function and social cognition in the diagnosis of frontotemporal dementia syndromes

Frontotemporal dementia (FTD) represents a spectrum of non-Alzheimer's degenerative conditions associated with focal atrophy of the frontal and/or temporal lobes. Frontal and temporal regions of the brain have been shown to be strongly involved in executive function, social cognition and language processing and, thus, deficits in these domains are frequently seen in patients with FTD or may even be hallmarks of a specific FTD subtype (i.e. relatively selective and progressive language impairment in primary progressive aphasia). In this review we have attempted to delineate how language, executive function, and social cognition may contribute to the diagnosis of FTD syndromes, namely the behavioural variant FTD as well as the language variants of FTD including the three subtypes of primary progressive aphasia (PPA): non-fluent/agrammatic, semantic and logopenic. This review also addresses the extent to which deficits in these cognitive areas contribute to the differential diagnosis of FTD versus Alzheimer's disease (AD). Finally, early clinical determinants of pathology are briefly discussed and contemporary challenges to the diagnosis of FTD are presented.

Primary progressive aphasia: classification of variants in 100 consecutive Brazilian cases

Primary progressive aphasia (PPA) is a neurodegenerative clinical syndrome characterized primarily by progressive language impairment. Recently, consensus diagnostic criteria were published for the diagnosis and classification of variants of PPA. The currently recognized variants are nonfluent/agrammatic (PPA-G), logopenic (PPA-L) and semantic (PPA-S).

Nonpharmacological interventions for cognitive impairments following primary progressive aphasia: a systematic review of the literature

This study provided a systematic review on nonpharmacological interventions applied to patients diagnosed with Primary Progressive Aphasia (PPA) and its variants: Semantic (SPPA), Nonfluent (NFPPA) and Logopenic (LPPA) to establish evidence-based recommendations for the clinical practice of cognitive rehabilitation for these patients.

METHODS

A PubMed and LILACS literature search with no time restriction was conducted with the keywords PPA (and its variants) AND rehabilitation OR training OR intervention OR therapy OR treatment OR effectiveness. To develop its evidence-based recommendations, a research committee identified questions to be addressed and determined the level of evidence for each study according to published criteria (Cicerone et al., 2000). Overall evidence for treatments was summarized and recommendations were derived.

RESULTS

Our search retrieved articles published from 1995 to 2013: 21 for SPPA, 8 for NFPPA, 3 for LPPA and 8 for PPA with no specification. Thirty-five studies were rated as Class III, consisting of studies with results obtained from one or more single-cases and that used appropriate single-subject methods with adequate quantification and analysis of results. The level of evidence of three functional interventions could not be established. One study was rated as Class II and consisted of a nonrandomized case-control investigation.

CONCLUSION

Positive results were reported in all reviewed studies. However, in order to be recommended, some investigation regarding the intervention efficacy was required. Results of the present review allows for recommendation of some nonpharmacological interventions for cognitive deficits following PPA as Practice Options. Suggestions for further studies on PPA interventions and future research are discussed.

Cerebrospinal fluid biomarkers for differentiation of frontotemporal lobar degeneration from Alzheimer's disease

Accurate ante mortem diagnosis in frontotemporal lobar degeneration (FTLD) is crucial to the development and implementation of etiology-based therapies. Several neurodegenerative disease-associated proteins, including the major protein constituents of inclusions in Alzheimer's disease (AD) associated with amyloid-beta (Aβ(1-42)) plaque and tau neurofibrillary tangle pathology, can be measured in cerebrospinal fluid (CSF) for diagnostic applications. Comparative studies using autopsy-confirmed samples suggest that CSF total-tau (t-tau) and Aβ(1-42) levels can accurately distinguish FTLD from AD, with a high t-tau to Aβ(1-42) ratio diagnostic of AD; however, there is also an urgent need for FTLD-specific biomarkers. These analytes will require validation in large autopsy-confirmed cohorts and face challenges of standardization of within- and between-laboratory sources of error. In addition, CSF biomarkers with prognostic utility and longitudinal study of CSF biomarker levels over the course of disease are also needed. Current goals in the field include identification of analytes that are easily and reliably measured and can be used alone or in a multi-modal approach to provide an accurate prediction of underlying neuropathology for use in clinical trials of disease modifying treatments in FTLD. To achieve these goals it will be of the utmost importance to view neurodegenerative disease, including FTLD, as a clinicopathological entity, rather than exclusively a clinical syndrome.

Artistic creativity and dementia

Artistic ability and creativity are defining characteristics of human behavior. Behavioral neurology, as a specialty, believes that even the most complex behaviors can be modeled and understood as the summation of smaller cognitive functions. Literature from individuals with specific brain lesions has helped to map out these smaller regions of cognitive abilities. More recently, models based on neurodegenerative conditions, especially from the frontotemporal dementias, have allowed for greater nuanced investigations into the various functional anatomies necessary for artistic behavior and possibly the underlying networks that promote creativity.

Syntactic and morphosyntactic processing in stroke-induced and primary progressive aphasia

The paper reports findings derived from three experiments examining syntactic and morphosyntactic processing in individuals with agrammatic and logopenic variants of primary progressive aphasia (PPA-G and PPA-L, respectively) and stroke-induced agrammatic and anomic aphasia (StrAg and StrAn, respectively). We examined comprehension and production of canonical and noncanonical sentence structures and production of tensed and nontensed verb forms using constrained tasks in experiments 1 and 2, using the Northwestern Assessment of Verbs and Sentences (NAVS [57]) and the Northwestern Assessment of Verb Inflection (NAVI, Thompson and Lee, experimental version) test batteries, respectively. Experiment 3 examined free narrative samples, focusing on syntactic and morphosyntactic measures, i.e. production of grammatical sentences, noun to verb ratio, open-class to closed-class word production ratio, and the production of correctly inflected verbs. Results indicate that the two agrammatic groups (i.e., PPA-G and StrAg) pattern alike on syntactic and morphosyntactic measures, showing more impaired noncanonical compared to canonical sentence comprehension and production and greater difficulties producing tensed compared to nontensed verb forms. Their spontaneous speech also contained significantly fewer grammatical sentences and correctly inflected verbs, and they produced a greater proportion of nouns compared to verbs, than healthy speakers. In contrast, PPA-L and StrAn individuals did not display these deficits, and performed significantly better than the agrammatic groups on these measures. The findings suggest that agrammatism, whether induced by degenerative disease or stroke, is associated with characteristic deficits in syntactic and morphosyntactic processing. We therefore recommend that linguistically sophisticated tests and narrative analysis procedures be used to systematically evaluate the linguistic ability of individuals with PPA, contributing to our understanding of the language impairments of different PPA variants.

The presenilin 1 P264L mutation presenting as non-fluent/agrammatic primary progressive aphasia

Primary progressive aphasia (PPA) represents a diverse group of language-led dementias most often due to frontotemporal lobar degeneration. We report clinical, neuropsychological, and neuroimaging data in the case of a 47-year-old woman presenting with non-fluent PPA due to a genetically confirmed pathogenic Presenilin 1 P264L mutation. This case highlights an unusual clinical presentation of familial Alzheimer's disease and a novel presentation of the P264L mutation. The case adds to accumulating evidence that particular mutations can promote specific brain network degeneration, with wider implications for understanding the sporadic forms of Alzheimer's disease and PPA.

The diagnosis and understanding of apraxia of speech: why including neurodegenerative etiologies may be important

PURPOSE

To discuss apraxia of speech (AOS) as it occurs in neurodegenerative disease (progressive AOS [PAOS]) and how its careful study may contribute to general concepts of AOS and help refine its diagnostic criteria.

METHOD

The article summarizes our current understanding of the clinical features and neuroanatomical and pathologic correlates of PAOS and its relationship to primary progressive aphasia (PPA). It addresses similarities and differences between PAOS and stroke-induced AOS that may be relevant to improving our understanding of AOS in general.

CONCLUSIONS

PAOS is clinical disorder that should be distinguished from PPA. Its recognition is important to clinical care provided by speech-language pathologists, but it also has implications for neurologic localization and diagnosis as well as prediction of underlying pathology and histochemistry. The clinical features of PAOS and stroke-induced AOS have not been explicitly compared, but they may not be identical because PAOS does not follow a vascular distribution, the brunt of cortical pathology is in the premotor and supplementary motor area, and its onset (rather than acute) is slowly progressive with potential for adaptation to gradual impairment. Careful description and study of PAOS may be a valuable source of information for refining our understanding of AOS in general.

The neural basis of syntactic deficits in primary progressive aphasia

Patients with primary progressive aphasia (PPA) vary considerably in terms of which brain regions are impacted, as well as in the extent to which syntactic processing is impaired. Here we review the literature on the neural basis of syntactic deficits in PPA. Structural and functional imaging studies have most consistently associated syntactic deficits with damage to left inferior frontal cortex. Posterior perisylvian regions have been implicated in some studies. Damage to the superior longitudinal fasciculus, including its arcuate component, has been linked with syntactic deficits, even after gray matter atrophy is taken into account. These findings suggest that syntactic processing depends on left frontal and posterior perisylvian regions, as well as intact connectivity between them. In contrast, anterior temporal regions, and the ventral tracts that link frontal and temporal language regions, appear to be less important for syntax, since they are damaged in many PPA patients with spared syntactic processing.

Loss of synaptophysin immunoexpression in primary progressive aphasia

Primary progressive aphasia (PPA) is characterized by progressive loss of language, unassociated with generalized cognitive loss and with no uniform pathological abnormality. To address whether the issue of PPA is associated with synaptic loss, we compared immunoreactivity in Broca's area with that in the adjacent gyrus from a case of progressive, nonfluent PPA using antibodies against synaptophysin. Using semiautomated methods, we assessed serial 0.10 mm(2) diameter areas from the cortical surface to the white matter in both the case and the control. In PPA, synaptophysin immunoreactivity was significantly less in Broca's area than in the adjacent area (optical densities of 0.16 and 0.24). The reduced synaptophysin immunoreactivity was significantly greater in the upper cortex than in the regions of cortex adjacent to the white matter (mean optical densities of 0.14 and 0.18). These data suggest that synaptic loss may be a factor underlying the language deficits in PPA.

Alzheimer's pathology in primary progressive aphasia

Primary progressive aphasia (PPA) is a neurodegenerative disorder with language impairment as the primary feature. Different subtypes have been described and the 3 best characterized are progressive nonfluent aphasia (PNFA), semantic dementia (SD) and logopenic/phonological aphasia (LPA). Of these subtypes, LPA is most commonly associated with Alzheimer's disease (AD) pathology. However, the features of PPA associated with AD have not been fully defined. Here we retrospectively identified 14 patients with PPA and either pathologically confirmed AD or cerebrospinal fluid (CSF) biomarkers consistent with AD. Analysis of neurological and neuropsychological features revealed that all patients had a syndrome of LPA with relatively nonfluent spontaneous speech, phonemic errors, and reduced digit span; most patients also had impaired verbal episodic memory. Analysis of the pattern of cortical thinning in these patients revealed left posterior superior temporal, inferior parietal, medial temporal, and posterior cingulate involvement and in patients with more severe disease, increasing involvement of left anterior temporal and frontal cortices and right hemisphere areas in the temporo-parietal junction, posterior cingulate, and medial temporal lobe. We propose that LPA may be a "unihemispheric" presentation of AD, and discuss this concept in relation to accumulating evidence concerning language dysfunction in AD.

Semantic interference during object naming in agrammatic and logopenic primary progressive aphasia (PPA)

This study examined the time course of object naming in 21 individuals with primary progressive aphasia (PPA) (8 agrammatic (PPA-G); 13 logopenic (PPA-L)) and healthy age-matched speakers (n=17) using a semantic interference paradigm with related and unrelated interfering stimuli presented at stimulus onset asynchronies (SOAs) of -1000, -500, -100 and 0 ms. Results showed semantic interference (SI) (i.e. significantly slower RTs in related compared to unrelated conditions) for all groups at -500, -100 and 0 ms, indicating timely spreading activation to semantic competitors. However, both PPA groups showed a greater magnitude of SI than normal across SOAs. The PPA-L group and six PPA-G participants also evinced SI at -1000 ms, suggesting an abnormal time course of semantic interference resolution, and concomitant left hemisphere cortical atrophy in brain regions associated with semantic processing. These subtle semantic mapping impairments in non-semantic variants of PPA may contribute to the anomia of these patients.

Pure word deafness in a patient with early-onset Alzheimer's disease: an unusual presentation

BACKGROUND AND PURPOSE

The occurrence of PWD in neurodegenerative disease is very rare, and this is the first report of it being related to early-onset AD. We describe a patient with early-onset Alzheimer's disease (AD) who presented with pure word deafness (PWD).

CASE REPORT

The patient had experienced PWD for 2 years, followed by other cognitive deficits suggestive of parietotemporal dysfunction. Brain imaging including (18)FDG-PET and [(11)C] PIB-PET supported the diagnosis of AD.

CONCLUSIONS

Our case highlights the clinical variability that characterizes early-onset AD.

Semantic dementia and persisting Wernicke's aphasia: linguistic and anatomical profiles

Few studies have directly compared the clinical and anatomical characteristics of patients with progressive aphasia to those of patients with aphasia caused by stroke. In the current study we examined fluent forms of aphasia in these two groups, specifically semantic dementia (SD) and persisting Wernicke's aphasia (WA) due to stroke. We compared 10 patients with SD to 10 age- and education-matched patients with WA in three language domains: language comprehension (single words and sentences), spontaneous speech and visual semantics. Neuroanatomical involvement was analyzed using disease-specific image analysis techniques: voxel-based morphometry (VBM) for patients with SD and overlays of lesion digitized lesion reconstructions in patients with WA. Patients with SD and WA were both impaired on tasks that involved visual semantics, but patients with SD were less impaired in spontaneous speech and sentence comprehension. The anatomical findings showed that different regions were most affected in the two disorders: the left anterior temporal lobe in SD and the left posterior middle temporal gyrus in chronic WA. This study highlights that the two syndromes classically associated with language comprehension deficits in aphasia due to stroke and neurodegenerative disease are clinically distinct, most likely due to distinct distributions of damage in the temporal lobe.

Progress in the last decade in our understanding of primary progressive aphasia

Primary progressive aphasia (PPA) is a focal neurodegeneration of the brain affecting the language network. Patients can have isolated language impairment for years without impairment in other areas. PPA is classified as primary progressive nonfluent aphasia (PNFA), semantic dementia (SD), and logopenic aphasia, which have distinct patterns of atrophy on neuroimaging. PNFA and SD are included under frontotemporal lobar degenerations. PNFA patients have effortful speech with agrammatism, which is frequently associated with apraxia of speech and demonstrate atrophy in the left Broca’s area and surrounding region on neuroimaging. Patients with SD have dysnomia with loss of word and object (or face) meaning with asymmetric anterior temporal lobe atrophy. Logopenic aphasics have word finding difficulties with frequent pauses in conversation, intact grammar, and word comprehension but impaired repetition for sentences. The atrophy is predominantly in the left posterior temporal and inferior parietal regions. Recent studies have described several progranulin mutations on chromosome 17 in PNFA. The three clinical syndromes have a less robust relationship to the underlying pathology, which is heterogeneous and includes tauopathy, ubiquitinopathy, Pick’s disease, corticobasal degeneration, progressive supranuclear palsy, and Alzheimer’s disease. Recent studies, however, seem to indicate that a better characterization of the clinical phenotype (apraxic, agrammatic, semantic, logopenic, jargon) increases the predictive value of the underlying pathology. Substantial advances have been made in our understanding of PPAs but developing new biomarkers is essential in making accurate causative diagnoses in individual patients. This is critically important in the development and evaluation of disease-modifying drugs.

Current and future AAC research considerations for adults with acquired cognitive and communication impairments

Adults with acquired language impairments secondary to stroke, traumatic brain injury, and neurodegenerative diseases are candidates for communication supports outside of the traditional restoration-based approaches to intervention. Recent research proves repeatedly that augmentative and alternative communication (AAC) provides a means for participation, engagement, conversation, and message transfer when individuals can no longer expect full return of pre-morbid communication skills and that inclusion of communication supports should begin early. We discuss current research and future directions for integrated systems of technical supports that include low-technology, high tech, and partner-dependent strategies for adults with severe and chronic aphasia, cognitive-communication problems resulting from traumatic brain injuries, and primary progressive aphasia.

Rehabilitation in semantic dementia: Study of effectiveness of lexical reacquisition in three patients

Although language rehabilitation in patients with primary progressive aphasia (PPA) is recommended, rehabilitation studies in this clinical syndrome are scarce. Specifically, in relation to semantic dementia (SD), few studies have shown the possibility of lexical relearning.

Objective

To analyze the effectiveness of rehabilitation for lexical reacquisition in SD.

Methods

Three SD patients were submitted to training for lexical reacquisition based on principles of errorless learning. Comparisons between naming performance of treated items (pre and post-training) and non-treated items of the Boston Naming Test (BNT) were made.

Results

All patients improved their performance in naming treated words after intervention. However, decline in performance in naming of non-treated items was observed. Case 1 named zero items at baseline while her performance post-training was 29.4% correct responses without cueing, and 90.7% correct with and without cueing. Case 2 named 6.9% of items correctly at baseline and his performance in post-training was 52.9% without cueing and 87.3%, with and without cueing. Case 3 named zero items at baseline and his performance in post-training was 100% correct responses without cueing. Considering the performance in naming the non-treated items of the BNT, the percentages of correct responses in the first evaluation and in the re-evaluation, respectively were: 16.7% and 8.3% (case 1; 14 month-interval); 26.7% and 11.6% (case 2; 18 month-interval) and 11.6% and 8.3% (case 3; 6 month-interval).

Conclusions

The reacquisition of lost vocabulary may be possible in SD despite progressive semantic deterioration.

The nature of naming errors in primary progressive aphasia versus acute post-stroke aphasia

OBJECTIVE

To compare the distribution of error types across subgroups of primary progressive aphasia and poststroke aphasia in different vascular locations.

METHOD

We analyzed naming errors in 49 individuals with acute left hemisphere ischemic stroke and 55 individuals with three variants of primary progressive aphasia. Location of atrophy or ischemic stroke was characterized using MRI.

RESULTS

We found that distribution of error types was very similar across all subgroups, irrespective of the site or etiology of the lesion. The only significant difference across groups was the percentage of circumlocutions (F(7, 96) = 3.02, p = .005). Circumlocution errors were highest among logopenic variant PPA (24%) and semantic variant PPA (24%). Semantic coordinate errors were common in all groups, probably because they can arise from disruption of different cognitive processes underlying naming and, therefore, from different locations of brain damage.

CONCLUSIONS

Semantic errors are common among all types of primary progressive aphasia and poststroke aphasia, and the type of error depends in part on the location of damage.

Connected speech production in three variants of primary progressive aphasia

Primary progressive aphasia is a clinical syndrome defined by progressive deficits isolated to speech and/or language, and can be classified into non-fluent, semantic and logopenic variants based on motor speech, linguistic and cognitive features. The connected speech of patients with primary progressive aphasia has often been dichotomized simply as 'fluent' or 'non-fluent', however fluency is a multidimensional construct that encompasses features such as speech rate, phrase length, articulatory agility and syntactic structure, which are not always impacted in parallel. In this study, our first objective was to improve the characterization of connected speech production in each variant of primary progressive aphasia, by quantifying speech output along a number of motor speech and linguistic dimensions simultaneously. Secondly, we aimed to determine the neuroanatomical correlates of changes along these different dimensions. We recorded, transcribed and analysed speech samples for 50 patients with primary progressive aphasia, along with neurodegenerative and normal control groups. Patients were scanned with magnetic resonance imaging, and voxel-based morphometry was used to identify regions where atrophy correlated significantly with motor speech and linguistic features. Speech samples in patients with the non-fluent variant were characterized by slow rate, distortions, syntactic errors and reduced complexity. In contrast, patients with the semantic variant exhibited normal rate and very few speech or syntactic errors, but showed increased proportions of closed class words, pronouns and verbs, and higher frequency nouns, reflecting lexical retrieval deficits. In patients with the logopenic variant, speech rate (a common proxy for fluency) was intermediate between the other two variants, but distortions and syntactic errors were less common than in the non-fluent variant, while lexical access was less impaired than in the semantic variant. Reduced speech rate was linked with atrophy to a wide range of both anterior and posterior language regions, but specific deficits had more circumscribed anatomical correlates. Frontal regions were associated with motor speech and syntactic processes, anterior and inferior temporal regions with lexical retrieval, and posterior temporal regions with phonological errors and several other types of disruptions to fluency. These findings demonstrate that a multidimensional quantification of connected speech production is necessary to characterize the differences between the speech patterns of each primary progressive aphasic variant adequately, and to reveal associations between particular aspects of connected speech and specific components of the neural network for speech production.

Primary progressive aphasia: clinical, imaging, and neuropathological findings

Primary Progressive Aphasia (PPA) is a neurodegenerative disorder initially presenting with progressive language imapirment. This article provides a clinically oriented review of PPA. Different clinical presentations and imaging findings of 3 subtypes, agrammatic, semantic and logopenic, are presented. Underlying neuropathology, medical and social management aspects of these patients are reviewed.

Progressive supranuclear palsy syndrome presenting as progressive nonfluent aphasia: a neuropsychological and neuroimaging analysis

There is currently considerable interest in the clinical spectrum of progressive nonfluent aphasia (PNFA) and progressive supranuclear palsy (PSP) and the intersection of these two entities. Here, we undertook a detailed prospective clinical, neuropsychological, and neuroimaging analysis of 14 consecutive patients presenting with PNFA to identify cases meeting clinical criteria for PSP. These patients had further detailed assessment of extrapyramidal and oculomotor functions. All patients had high-resolution MR brain volumetry and a cortical thickness analysis was undertaken on the brain images. Four patients presenting with PNFA subsequently developed features of a PSP syndrome, including a typical oculomotor palsy. The neuropsychological profile in these cases was similar to other patients with PNFA, however, with more marked reduction in propositional speech, fewer speech errors, less marked impairment of literacy skills but more severe associated deficits of episodic memory and praxis. These PSP-PNFA cases had less prominent midbrain atrophy but more marked prefrontal atrophy than a comparison group of five patients with pathologically confirmed PSP without PNFA and more prominent midbrain atrophy but less marked perisylvian atrophy than other PNFA cases. In summary, although the PSP-PNFA syndrome overlaps with PNFA without PSP, certain neuropsychological and neuroanatomical differences may help predict the development of a PSP syndrome.

Progressive logopenic/phonological aphasia: erosion of the language network

The primary progressive aphasias (PPA) are paradigmatic disorders of language network breakdown associated with focal degeneration of the left cerebral hemisphere. Here we addressed brain correlates of PPA in a detailed neuroanatomical analysis of the third canonical syndrome of PPA, logopenic/phonological aphasia (LPA), in relation to the more widely studied clinico-anatomical syndromes of semantic dementia (SD) and progressive nonfluent aphasia (PNFA). 32 PPA patients (9 SD, 14 PNFA, 9 LPA) and 18 cognitively normal controls had volumetric brain MRI with regional volumetry, cortical thickness, grey and white matter voxel-based morphometry analyses. Five of nine patients with LPA had cerebrospinal fluid biomarkers consistent with Alzheimer (AD) pathology (AD-PPA) and 2/9 patients had progranulin (GRN) mutations (GRN-PPA). The LPA group had tissue loss in a widespread left hemisphere network. Compared with PNFA and SD, the LPA group had more extensive involvement of grey matter in posterior temporal and parietal cortices and long association white matter tracts. Overlapping but distinct networks were involved in the AD-PPA and GRN-PPA subgroups, with more anterior temporal lobe involvement in GRN-PPA. The importance of these findings is threefold: firstly, the clinico-anatomical entity of LPA has a profile of brain damage that is complementary to the network-based disorders of SD and PNFA; secondly, the core phonological processing deficit in LPA is likely to arise from temporo-parietal junction damage but disease spread occurs through the dorsal language network (and in GRN-PPA, also the ventral language network); and finally, GRN mutations provide a specific molecular substrate for language network dysfunction.

Neologistic jargon aphasia and agraphia in primary progressive aphasia

The terms 'jargon aphasia' and 'jargon agraphia' describe the production of incomprehensible language containing frequent phonological, semantic or neologistic errors in speech and writing, respectively. Here we describe two patients with primary progressive aphasia (PPA) who produced neologistic jargon either in speech or writing. We suggest that involvement of the posterior superior temporal-inferior parietal region may lead to a disconnection between stored lexical representations and language output pathways leading to aberrant activation of phonemes in neologistic jargon. Parietal lobe involvement is relatively unusual in PPA, perhaps accounting for the comparative rarity of jargon early in the course of these diseases.

Generalized and symptom-specific insight in behavioral variant frontotemporal dementia and primary progressive aphasia

Behavioral variant frontotemporal dementia (FTD) and primary progressive aphasia (PPA) are related dementias with different presenting symptoms but with increasing symptom overlap as they progress. Loss of insight is associated with early behavioral variant FTD, but not PPA. This study used the Frontal Behavioral Inventory to compare patient and caregiver concepts of symptom presence and severity. Patients with behavioral variant FTD were found to have worse insight overall than PPA patients. However, the PPA group showed reduced insight into behavioral symptoms, and the behavioral variant FTD groups had intact insight into some language symptoms. Theoretical and clinical implications are discussed.