Logopenic syndrome in posterior cortical atrophy. J Neurol. 2013;260:528-533. [PMID: 23007194 DOI: 10.1007/s00415-012-6671-7]

Atypical Alzheimer's disease: new insights into an overlapping spectrum between the language and visual variants

Overlap between language and visual variants of atypical Alzheimer's disease (AD) has been reported. However, the extent, frequency of overlap, and its neuroanatomical underpinnings remain unclear. Eighty-two biomarker-confirmed AD patients who presented with either predominant language (n = 34) or visuospatial/perceptual (n = 48) deficits underwent detailed clinical examinations, MRI, and [18F]flortaucipir-PET. Subgroups were defined based on language/visual testing and patterns of volume loss and tau uptake were assessed. 28% of the language group had visual dysfunction (marked in 8%), and 47% of the visual group had language impairment (marked in 26%). Progressive involvement of the parieto-occipital and frontal lobes was noted with greater visual impairment in the language group, and greater left parieto-temporal and frontal involvement with worsening language impairment in the visual group. Only 25% of our cohort showed a pure language or visual presentation, highlighting the high frequency of syndromic overlap in atypical AD and the diagnostic challenge of categorical phenotyping.

Secondary language impairment in posterior cortical atrophy: insights from sentence repetition

Introduction

Posterior cortical atrophy (PCA) is a neurodegenerative syndrome characterized by progressive impairment in visuospatial and perceptual function linked to atrophy of the occipito-parietal cortex. Besides the salient visual impairment, several studies have documented subtle changes in language may also be present. Sentence repetition is a highly constrained linguistic task involving multiple linguistic and cognitive processes and have been shown to be impaired in other AD spectrum disorders, with little consensus on its relevance in PCA. This aim of this study was to further delineate the linguistic and cognitive features of impaired language in PCA using a sentence repetition task.

Method

Seven PCA patients and 16 healthy controls verbally repeated 16 sentences from the Boston Diagnostic Aphasia Examination. Responses were transcribed orthographically and coded for accuracy (percentage accuracy; percentage Correct Information Units; Levenshtein Distance) and for temporal characteristics (preparation duration (ms); utterance duration (ms); silent pause duration (ms); speech duration (ms); dysfluency duration (ms)). The potential modulating effects of attentional control and working memory capacity were explored.

Results

PCA patients showed lower overall accuracy with retained semantic content of the sentences, and lower phonological accuracy. Temporal measures revealed longer preparation and utterance duration for PCA patients compared to controls, alongside longer speech duration but comparable dysfluency duration. PCA patients also showed comparable silent pause duration to controls. Attentional control, measured using the Hayling sentence completion task, predicted accuracy of sentence repetition.

Discussion

The findings suggest that sentence repetition is impaired in PCA and is characterized by phonological, response planning and execution difficulties, underpinned in part by attentional control mechanisms. The emerging profile of language impairment in PCA suggests vulnerability of similar cognitive systems to other Alzheimer's syndromes, with subtle differences in clinical presentation.

Auditory naming is impaired in posterior cortical atrophy and early-onset Alzheimer's disease

Introduction

Visual naming ability reflects semantic memory retrieval and is a hallmark deficit of Alzheimer's disease (AD). Naming impairment is most prominently observed in the late-onset amnestic and logopenic variant Primary Progressive Aphasia (lvPPA) syndromes. However, little is known about how other patients across the atypical AD syndromic spectrum perform on tests of auditory naming, particularly those with primary visuospatial deficits (Posterior Cortical Atrophy; PCA) and early onset (EOAD) syndromes. Auditory naming tests may be of particular relevance to more accurately measuring anomia in PCA syndrome and in others with visual perceptual deficits.

Methods

Forty-six patients with biomarker-confirmed AD (16 PCA, 12 lvPPA, 18 multi-domain EOAD), at the stage of mild cognitive impairment or mild dementia, were administered the Auditory Naming Test (ANT). Performance differences between groups were evaluated using one-way ANOVA and post-hoc t-tests. Correlation analyses were used to examine ANT performance in relation to measures of working memory and word retrieval to elucidate cognitive mechanisms underlying word retrieval deficits. Whole-cortex general linear models were generated to determine the relationship between ANT performance and cortical atrophy.

Results

Based on published cutoffs, out of a total possible score of 50 on the ANT, 56% of PCA patients (mean score = 45.3), 83% of EOAD patients (mean = 39.2), and 83% of lvPPA patients (mean = 29.8) were impaired. Total uncued ANT performance differed across groups, with lvPPA performing most poorly, followed by EOAD, and then PCA. ANT performance was still impaired in lvPPA and EOAD after cuing, while performance in PCA patients improved to the normal range with phonemic cues. ANT performance was also directly correlated with measures of verbal fluency and working memory, and was associated with cortical atrophy in a circumscribed semantic language network.

Discussion

Auditory confrontation naming is impaired across the syndromic spectrum of AD including in PCA and EOAD, and is likely related to auditory-verbal working memory and verbal fluency which represent the nexus of language and executive functions. The left-lateralized semantic language network was implicated in ANT performance. Auditory naming, in the absence of a visual perceptual demand, may be particularly sensitive to measuring naming deficits in PCA.

Altered within- and between-network functional connectivity in atypical Alzheimer's disease

Posterior cortical atrophy and logopenic progressive aphasia are atypical clinical presentations of Alzheimer's disease. Resting-state functional connectivity studies have shown functional network disruptions in both phenotypes, particularly involving the language network in logopenic progressive aphasia and the visual network in posterior cortical atrophy. However, little is known about how connectivity differs both within and between brain networks in these atypical Alzheimer's disease phenotypes. A cohort of 144 patients was recruited by the Neurodegenerative Research Group at Mayo Clinic, Rochester, MN, USA, and underwent structural and resting-state functional MRI. Spatially preprocessed data were analysed to explore the default mode network and the salience, sensorimotor, language, visual and memory networks. The data were analysed at the voxel and network levels. Bayesian hierarchical linear models adjusted for age and sex were used to analyse within- and between-network connectivity. Reduced within-network connectivity was observed in the language network in both phenotypes, with stronger evidence of reductions in logopenic progressive aphasia compared to controls. Only posterior cortical atrophy showed reduced within-network connectivity in the visual network compared to controls. Both phenotypes showed reduced within-network connectivity in the default mode and sensorimotor networks. No significant change was noted in the memory network, but a slight increase in the salience within-network connectivity was seen in both phenotypes compared to controls. Between-network analysis in posterior cortical atrophy showed evidence of reduced visual-to-language network connectivity, with reduced visual-to-salience network connectivity, compared to controls. An increase in visual-to-default mode network connectivity was noted in posterior cortical atrophy compared to controls. Between-network analysis in logopenic progressive aphasia showed evidence of reduced language-to-visual network connectivity and an increase in language-to-salience network connectivity compared to controls. Findings from the voxel-level and network-level analysis were in line with the Bayesian hierarchical linear model analysis, showing reduced connectivity in the dominant network based on diagnosis and more crosstalk between networks in general compared to controls. The atypical Alzheimer's disease phenotypes were associated with disruptions in connectivity, both within and between brain networks. Phenotype-specific differences in connectivity patterns were noted in the visual network for posterior cortical atrophy and the language network for logopenic progressive aphasia.

Diagnosis and Management of Posterior Cortical Atrophy

Purpose of review

The study aims to provide a summary of recent developments for diagnosing and managing posterior cortical atrophy (PCA). We present current efforts to improve PCA characterisation and recommendations regarding use of clinical, neuropsychological and biomarker methods in PCA diagnosis and management and highlight current knowledge gaps.

Recent findings

Recent multi-centre consensus recommendations provide PCA criteria with implications for different management strategies (e.g. targeting clinical features and/or disease). Studies emphasise the preponderance of primary or co-existing Alzheimer's disease (AD) pathology underpinning PCA. Evidence of approaches to manage PCA symptoms is largely derived from small studies.

Summary

PCA diagnosis is frequently delayed, and people are likely to receive misdiagnoses of ocular or psychological conditions. Current treatment of PCA is symptomatic - pharmacological and non-pharmacological - and the use of most treatment options is based on small studies or expert opinion. Recommendations for non-pharmacological approaches include interdisciplinary management tailored to the PCA clinical profile - visual-spatial - rather than memory-led, predominantly young onset - and psychosocial implications. Whilst emerging disease-modifying treatments have not been tested in PCA, an accurate and timely diagnosis of PCA and determining underlying pathology is of increasing importance in the advent of disease-modifying therapies for AD and other albeit rare causes of PCA.

Understanding the multidimensional cognitive deficits of logopenic variant primary progressive aphasia

The logopenic variant of primary progressive aphasia is characterized by early deficits in language production and phonological short-term memory, attributed to left-lateralized temporoparietal, inferior parietal and posterior temporal neurodegeneration. Despite patients primarily complaining of language difficulties, emerging evidence points to performance deficits in non-linguistic domains. Temporoparietal cortex, and functional brain networks anchored to this region, are implicated as putative neural substrates of non-linguistic cognitive deficits in logopenic variant primary progressive aphasia, suggesting that degeneration of a shared set of brain regions may result in co-occurring linguistic and non-linguistic dysfunction early in the disease course. Here, we provide a Review aimed at broadening the understanding of logopenic variant primary progressive aphasia beyond the lens of an exclusive language disorder. By considering behavioural and neuroimaging research on non-linguistic dysfunction in logopenic variant primary progressive aphasia, we propose that a significant portion of multidimensional cognitive features can be explained by degeneration of temporal/inferior parietal cortices and connected regions. Drawing on insights from normative cognitive neuroscience, we propose that these regions underpin a combination of domain-general and domain-selective cognitive processes, whose disruption results in multifaceted cognitive deficits including aphasia. This account explains the common emergence of linguistic and non-linguistic cognitive difficulties in logopenic variant primary progressive aphasia, and predicts phenotypic diversification associated with progression of pathology in posterior neocortex.

Atypical Alzheimer's disease phenotypes with normal or borderline PET biomarker profiles

Posterior cortical atrophy (PCA) and logopenic progressive aphasia (LPA) are clinical syndromes that commonly have underlying Alzheimer's disease (AD), although non-AD pathologies have also been reported. PET imaging allows for identification of beta-amyloid (Aβ) and tau in AD, so we aimed to assess these in a large cohort to identify patients that do not have evidence for biomarker-defined AD. Eight-one patients, 47 PCA and 34 LPA, underwent extensive neurological and neuropsychological testing, [¹¹C] Pittsburgh compound B, [¹⁸F] flortaucipir and [¹⁸F] fluorodeoxyglucose PETs. Global Aβ and tau-PET standardized uptake value ratios (SUVRs) were plotted for all patients and outliers, and patients with abnormally low SUVRs compared to the biomarker-classic cohort were identified. Six (7.4%) biomarker-outlier cases were identified, and three patterns were observed: (i) negative/borderline Aβ-PET and striking widespread tau-PET uptake (two LPA); (ii) negative/borderline Aβ-PET and low tau-PET uptake (three PCA) and (iii) elevated Aβ-PET uptake but mild focal tau-PET uptake (one LPA). Among the unusual patients in group ii, two patients showed no abnormal tau uptake suggesting non-AD pathology, with one developing features of cortico-basal syndrome and the other dementia with Lewy bodies. The remaining patient showed very mild focal tau uptake. This study demonstrates that a small minority (~ 8%) of PCA and LPA patients do not show the typical striking patterns of Aβ and tau PET uptake, with only 2% showing absence of both proteins. These findings will help inform the use of molecular PET in clinical treatment trials that include patients with atypical phenotypes of AD.

Atypical Alzheimer Disease Variants

PURPOSE OF REVIEW

This article discusses the clinical, neuroimaging, and biomarker profiles of sporadic atypical Alzheimer disease (AD) variants, including early-onset AD, posterior cortical atrophy, logopenic variant primary progressive aphasia, dysexecutive variant and behavioral variant AD, and corticobasal syndrome.

RECENT FINDINGS

Significant advances are being made in the recognition and characterization of the syndromically diverse AD variants. These variants are identified by the predominant cognitive and clinical features: early-onset amnestic syndrome, aphasia, visuospatial impairments, dysexecutive and behavioral disturbance, or motor symptoms. Although understanding of regional susceptibility to disease remains in its infancy, visualizing amyloid and tau pathology in vivo and CSF examination of amyloid-β and tau proteins are particularly useful in atypical AD, which can be otherwise prone to misdiagnosis. Large-scale research efforts, such as LEADS (the Longitudinal Early-Onset Alzheimer Disease Study), are currently ongoing and will continue to shed light on our understanding of these diverse presentations.

SUMMARY

Understanding the clinical, neuroimaging, and biomarker profiles of the heterogeneous group of atypical AD syndromes improves diagnostic accuracy in patients who are at increased risk of misdiagnosis. Earlier accurate identification facilitates access to important interventions, social services and disability assistance, and crucial patient and family education.

Primary and Secondary Progressive Aphasia in Posterior Cortical Atrophy

Background: Posterior cortical atrophy (PCA) is a clinico-radiological syndrome characterized by a progressive decline in visuospatial/visuoperceptual processing. PCA is accompanied by the impairment of other cognitive functions, including language abilities. Methods: The present study focused on three patients presenting with language complaints and a clinical profile that was compatible with PCA. In addition to neurological and neuroimaging examinations, they were assessed with comprehensive batteries of neuropsychological and neurolinguistic tests. Results: The general medical profile of the three patients is consistent with PCA, although they presented with confounding factors, making diagnosis less clear. The cognitive profile of the three patients was marked by Balint and Gerstmann’s syndromes as well as impairments affecting executive functions, short-term and working memory, visuospatial and visuoperceptual abilities, and sensorimotor execution abilities. Their language ability was characterized by word-finding difficulties and impairments of sentence comprehension, sentence repetition, verbal fluency, narrative speech, reading, and writing. Conclusions: This study confirmed that PCA is marked by visuospatial and visuoperceptual deficits and reported evidence of primary and secondary language impairments in the three patients. The similarities of some of their language impairments with those found in the logopenic variant of primary progressive aphasia is discussed from neurolinguistic and neuroanatomical points of view.

Neuropsychological deficits in Posterior Cortical Atrophy and typical Alzheimer's disease: A meta-analytic review

AIMS

To identify cognitive tests that best differentiate between Posterior Cortical Atrophy (PCA) and typical Alzheimer's Disease (tAD), as well as PCA and healthy control (HC) participants.

METHOD

Medline, PsycInfo and Web of Science were systematically searched using terms related to PCA, tAD, and cognitive testing. Seventeen studies were identified, including 441 PCA, 391 tAD, and 284 HC participants. Standardised effect sizes of mean scores were calculated to measure performance differences on cognitive tests for PCA versus tAD and PCA versus HC groups. Meta-analyses used a random effects model.

RESULTS

The most discriminating cognitive tests for PCA and tAD presentations were measures of visuospatial function and verbal memory. Large, significant effect sizes were produced for all measures of visuospatial function, most notably for Rey-Osterrieth Copy (Hedges' g = -2.79), VOSP Fragmented letters (Hedges' g = -1.73), VOSP Dot Counting (Hedges' g = -1.74), and VOSP Cube Analysis (Hedges' g = -1.98). For measures of verbal memory, the RAVLT delay and Digit Span Backwards produced significant medium effects (Hedges' g = .62 and -.56, respectively).

CONCLUSION

Establishing a common framework for testing individuals with PCA has important implications for diagnosis and treatment, and forms a practical objective for future research. Findings from this meta-analysis suggest that measures of visuospatial function and verbal memory would form an important part of this framework.

When it is not primary progressive aphasia: A scoping review of spoken language impairment in other neurodegenerative dementias

BACKGROUND

Progressive difficulties with spoken language occur across the spectrum of degenerative dementia. When not a primary presenting and dominant symptom, language difficulties may be overlooked in favor of more prominent cognitive, behavior, or motor deficits. The aim of this scoping review is to examine the extent and nature of the research evidence describing (1) the spoken language impairments found in non-language led dementias, (2) their impact on everyday living, and (3) the reported language interventions.

METHODS

We searched PubMed, MEDLINE, OVID-EMBASE, PsycINFO, and SpeechBITE using terms related to spoken language for the following dementia types: Parkinson's disease dementia (PDD), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), cortico-basal syndrome (CBS), behavior variant frontotemporal dementia (bvFTD), early-onset Alzheimer's disease (EOAD), posterior cortical atrophy (PCA), and motor neuron disease associated with FTD (MND+FTD). Risk of bias was assessed with the QualSyst tool.

RESULTS

Seventy-three eligible studies were included. A wide range of spoken language impairments were reported, involving both linguistic (e.g., syntactic processing) and other cognitive (e.g., sustained attention) underlying mechanisms. Although the severity of these deficits was scarcely reported, in some cases they manifested as non-fluent, dynamic, and global aphasias. No papers in the review described either the impact of these language impairments on everyday living or language therapies to treat them.

DISCUSSION

There is a need to understand better the level of disability produced by language impairment in people living with non-language-led dementias. Our findings suggest three calls for action: (1) research studies should assess the clinical relevance of any spoken language deficits examined, (2) both linguistic and cognitive underlying mechanisms should be fully described (to inform the design of effective language and behavioral interventions), and (3) trials of language therapy should be conducted in those groups of individuals where significant language impairment is proved.

Cognitive Profile of the Logopenic Variant of Primary Progressive Aphasia Using the Dépistage Cognitif de Québec

BACKGROUND/AIMS

The logopenic variant of primary progressive aphasia (lvPPA) is characterized by impaired word-finding and sentence repetition with phonologic errors but spared motor speech and grammar and semantic knowledge. Although its language deficits have been well studied, the full spectrum of cognitive changes in the lvPPA remains to be defined. We aimed to explore the neurocognitive profile of the lvPPA using a newly developed cognitive screening tool for atypical dementias, the Dépistage Cognitif de Québec (DCQ).

METHODS

We compared 29 patients with lvPPA to 72 amnestic variant Alzheimer disease (aAD) to 438 healthy control (HC) participants. Performance on the 5 indexes of the DCQ (Memory, Visuospatial, Executive, Language and Behavioral) was compared between the 3 groups.

RESULTS

Results showed a significantly lower performance for lvPPA participants in all neurocognitive domains, when compared to HC. When compared to aAD, lvPPA participants had significantly lower scores for language, executive, and visuospatial abilities, but not for memory and behavior.

CONCLUSION

Altogether, these findings better define the neurocognitive changes of lvPPA.

A systematic review of atypical Alzheimer's disease including behavioural and psychological symptoms

Alzheimer's disease (AD) is the commonest cause of dementia, characterized by the clinical presentation of progressive anterograde episodic memory impairment. However, atypical presentation of patients is increasingly recognized. These atypical AD include logopenic aphasia, behavioural variant AD, posterior cortical atrophy, and corticobasal syndrome. These atypical AD are more common in patients with young onset AD before the age of 65 years old. Since medical needs (including the behavioural and psychological symptoms of dementia) of atypical AD patients could be different from typical AD patients, it is important for clinicians to be aware of these atypical forms of AD. In addition, disease modifying treatment may be available in the future. This review aims at providing an update on various important subtypes of atypical AD including behavioural and psychological symptoms.

Phonological Errors in Posterior Cortical Atrophy

BACKGROUND

Posterior cortical atrophy (PCA) is an atypical variant of Alzheimer's disease (AD) that presents with visuospatial/perceptual deficits. PCA is characterized by atrophy in posterior brain regions, which overlaps with atrophy occurring in logopenic variant of primary progressive aphasia (lvPPA), another atypical AD variant characterized by language difficulties, including phonological errors. Language abnormalities have been observed in PCA, although the prevalence of phonological errors is unknown. We aimed to compare the frequency and severity of phonological errors in PCA and lvPPA and determine the neuroanatomical correlates of phonological errors and language abnormalities in PCA.

METHODS

The presence and number of phonological errors were recorded during the Boston Naming Test and Western Aphasia Battery repetition subtest in 27 PCA patients and 27 age- and disease duration-matched lvPPA patients. Number of phonological errors and scores from language tests were correlated with regional gray matter volumes using Spearman correlations.

RESULTS

Phonological errors were evident in 55% of PCA patients and 70% of lvPPA patients, with lvPPA having higher average number of errors. Phonological errors in PCA correlated with decreased left inferior parietal and lateral temporal volume. Naming and fluency were also associated with decreased left lateral temporal lobe volume.

CONCLUSIONS

Phonological errors are common in PCA, although they are not as prevalent or severe as in lvPPA, and they are related to involvement of left temporoparietal cortex. This highlights the broad spectrum of clinical symptoms associated with AD and overlap between PCA and lvPPA.

Word retrieval across the biomarker-confirmed Alzheimer's disease syndromic spectrum

Alzheimer's disease (AD) is now conceptualized as a biological entity defined by amyloid and tau deposition and neurodegeneration, with heterogeneous clinical presentations. With the aid of in vivo biomarkers, clinicians are better poised to examine clinical syndromic variability arising from a common pathology. Word retrieval deficits, measured using verbal fluency and confrontation naming tests, are hallmark features of the early clinical stages of the amnestic presentations of AD, specifically in category fluency and naming with relatively spared letter fluency. As yet, there is no consensus regarding performance on these tests in atypical clinical phenotypes of AD, including posterior cortical atrophy (PCA) and logopenic primary progressive aphasia (lvPPA), in individuals who are amyloid-positive (Aβ+) but present with different clinical profiles and patterns of neurodegeneration compared to amnestic AD. The goal of the current study is to determine how Aβ+ individuals across the syndromic spectrum of AD perform on three different word retrieval tasks. A secondary goal is to determine the neuroanatomical substrates underlying word retrieval performance in these Aβ+ individuals. Thirty-two Aβ+ participants with the amnestic presentation, 16 with Aβ+ PCA, 22 with Aβ+ lvPPA, and 99 amyloid-negative (Aβ-) control participants were evaluated with verbal fluency and visual confrontation naming tests as well as high-resolution MRI. The Aβ+ patient groups were rated at very mild or mild levels of severity (CDR 0.5 or 1) and had comparable levels of global cognitive impairment (average MMSE = 23.7 ± 3.9). Behaviorally, we found that the word retrieval profile of PCA patients is comparable to that of amnestic patients, characterized by intact letter fluency but impaired category fluency and visual confrontation naming, while lvPPA patients demonstrated impairment across all tests of word retrieval. Across all AD variants, we observed that letter fluency was associated with cortical thickness in prefrontal, central precuneus, lateral parietal and temporal cortex, while category fluency and naming were associated with cortical thickness in left middle frontal gyrus, posterior middle temporal gyrus, and lateral parietal cortex. Visual confrontation naming was uniquely associated with atrophy in inferior temporal and visual association cortex. We conclude that a better understanding of the word retrieval profiles and underlying neurodegeneration across the AD syndromic spectrum will help improve interpretation of neuropsychological profiles with regard to the localization of neurodegeneration, particularly in the atypical AD variants.

Early-onset Alzheimer Disease and Its Variants

PURPOSE OF REVIEW

Early-onset Alzheimer disease (AD) is defined as having an age of onset younger than 65 years. While early-onset AD is often overshadowed by the more common late-onset AD, recognition of the differences between early- and late-onset AD is important for clinicians.

RECENT FINDINGS

Early-onset AD comprises about 5% to 6% of cases of AD and includes a substantial percentage of phenotypic variants that differ from the usual amnestic presentation of typical AD. Characteristics of early-onset AD in comparison to late-onset AD include a larger genetic predisposition (familial mutations and summed polygenic risk), more aggressive course, more frequent delay in diagnosis, higher prevalence of traumatic brain injury, less memory impairment and greater involvement of other cognitive domains on presentation, and greater psychosocial difficulties. Neuroimaging features of early-onset AD in comparison to late-onset AD include greater frequency of hippocampal sparing and posterior neocortical atrophy, increased tau burden, and greater connectomic changes affecting frontoparietal networks rather than the default mode network.

SUMMARY

Early-onset AD differs substantially from late-onset AD, with different phenotypic presentations, greater genetic predisposition, and differences in neuropathologic burden and topography. Early-onset AD more often presents with nonamnestic phenotypic variants that spare the hippocampi and with greater tau burden in posterior neocortices. The early-onset AD phenotypic variants involve different neural networks than typical AD. The management of early-onset AD is similar to that of late-onset AD but with special emphasis on targeting specific cognitive areas and more age-appropriate psychosocial support and education.

Posterior Cortical Atrophy

PURPOSE OF REVIEW

This article presents an overview of the clinical syndrome of posterior cortical atrophy (PCA), including its pathologic underpinnings, clinical presentation, investigation findings, diagnostic criteria, and management.

RECENT FINDINGS

PCA is usually an atypical form of Alzheimer disease with relatively young age at onset. New diagnostic criteria allow patients to be diagnosed on a syndromic basis as having a primary visual (pure) form or more complex (plus) form of PCA and, when possible, on a disease-specific basis using biomarkers or underlying pathology. Imaging techniques have demonstrated that some pathologic processes are concordant (atrophy, hypometabolism, tau deposition) with clinical symptoms and some are discordant (widespread amyloid deposition). International efforts are under way to establish the genetic underpinnings of this typically sporadic form of Alzheimer disease. In the absence of specific disease-modifying therapies, a number of practical suggestions can be offered to patients and their families to facilitate reading and activities of daily living, promote independence, and improve quality of life SUMMARY: While rare, PCA is an important diagnostic entity for neurologists, ophthalmologists, and optometrists to recognize to allow for early accurate diagnosis and appropriate patient management. PCA provides an important opportunity to investigate the causes of selective vulnerability in Alzheimer disease.

Clinical and neuroimaging characteristics of clinically unclassifiable primary progressive aphasia

Many patients who meet core/root criteria for Primary Progressive Aphasia (PPA) are not classifiable as a recognized variant and are often excluded from neuroimaging studies. Here, we detail neurological, neuropsychological, speech and language assessments, and anatomic and molecular neuroimaging (MRI, PiB-PET, and FDG-PET) for fifteen (8 female) clinically unclassifiable PPA patients. Median age of onset was 64 years old with median 3 years disease duration at exam. Three patients were amyloid positive on PiB-PET. 14/15 patients had abnormal FDG-PETs with left predominant hypometabolism, affecting frontal, temporal, parietal, and even occipital lobes. Patients had mild to severe clinical presentations. Visualization of the FDG-PETs principal component analysis revealed patterns of hypometabolism similar to those seen in the PPA variants and suggests the brain regions affected in unclassifiable PPA patients are no different from those who are more easily classifiable. These findings may inform future modifications to the diagnostic criteria to improve diagnostic classification.

Posterior Cortical Atrophy: Does Complaint Match the Impairment? A Neuropsychological and FDG-PET Study

Objective: Posterior Cortical Atrophy (PCA) is a neurodegenerative disease characterized predominantly by visual impairment. However, diagnosis of PCA remains complicated with an interval of several years between initial reporting of symptoms and diagnosis. The aim of the present study is to define if patients' visual and gestural complaints are consistent with their clinical profile.

Method: An evaluation of daily visual problems as well as a full neuropsychological assessment and FDG-PET were performed in 15 PCA patients. We compared glucose metabolism between these PCA patients and 18 healthy controls. Correlation analyses were conducted in PCA patients between visual and gestural complaint, clinical impairments, and brain glucose metabolism.

Results: Major impairment of cognitive functions was detected in PCA patients specifically in visual domains. Positive correlations were found between visual impairments and hypometabolism in the right temporo-parieto-occipital cortices. However, no correlation was found between complaint and visual impairment in PCA patients.

Discussion: Our main results suggest a consistent relationship between clinical impairment and brain metabolism. However, the patient's complaint and visual performance are not linked. Combining the literature and our results, it seems that patients are generally aware of difficulties but misinterpret them. This misinterpretation may be responsible for the delayed diagnosis.

A Case of Overlap Posterior Cortical Atrophy and Logopenic Variant Primary Progressive Aphasia

Posterior cortical atrophy (PCA) and logopenic variant primary progressive aphasia (LvPPA) are considered early-onset dementias most commonly caused by Alzheimer pathology. PCA is characterized by a progressive decline in higher order visual processing functions, whereas LvPPA is a form of primary progressive aphasia. The clinical presentation of both syndromes is typically earlier in life relative to the more typical "amnestic" form of Alzheimer disease. Prominent language deficits have been well described in PCA. Here, we describe the case of a 56-year-old man presenting with overlapping anatomic, clinical, and cognitive features of PCA and LvPPA and review the existing literature relating to the clinical features shared by these conditions, exploring the etiology, and implications for clinical practice in cases with a PCA-LvPPA overlap syndrome. In PCA, atrophy occurs in temporoparietal-occipital regions, whereas in LvPPA atrophy occurs at the temporoparietal junctions, with left-sided predominance. A defective phonological loop (a short-term storage system which holds speech sounds in memory for 1 to 2 s) seems to underlie the logopenic syndrome in both conditions. Other parietal lobe deficits, in proximity to both language and visual processing areas, such as dyscalculia and ideomotor apraxia are also commonly found in both conditions. We suspect that cases with an overlap PCA-LvPPA syndrome are relatively underreported which may relate to the fact that these cases occur on a spectrum depending on the stage of disease progression and do not easily fit into strict diagnostic categories according to existing criteria of PCA and LvPPA, respectively.

Executive dysfunction contributes to verbal encoding and retrieval deficits in posterior cortical atrophy

Posterior Cortical Atrophy (PCA) is a neurodegenerative syndrome that typically presents with predominant visual and spatial impairments. The early diagnostic criteria specify a relative sparing of functioning in other cognitive domains, including executive functions, language, and episodic memory, yet little is known of the cognitive profile of PCA as the disease progresses. Studies of healthy adults and other posterior cortical lesion patients implicate posterior parietal and temporal regions in executive functions of working memory and verbal fluency, both of which may impact episodic memory. Relatively little has been reported about these cognitive functions in PCA, and to our knowledge there has not yet been a study of the impact of such deficits on memory function in PCA. We sought to examine PCA patients' performance on tests of executive function and the associations to verbal episodic memory encoding, storage, and delayed recall. Nineteen individuals with PCA underwent neuropsychological and neuroimaging evaluations as part of a comprehensive clinical assessment. We developed a novel consensus rating method-the Neuropsychological Assessment Rating (NAR) scale-to grade the severity of test performance impairments in selected cognitive domains and subdomains. Hypothesis-driven analyses demonstrated relative deficits in working memory and lexical-semantic retrieval. Preliminary analyses suggested associations between both deficits and atrophy in the left-hemisphere inferior parietal lobule. These executive deficits were also associated with impairments in verbal encoding and delayed recall, but not with recognition discriminability. We conclude that deficits in verbal executive functions impact verbal episodic memory in PCA. Our findings also support theories emphasizing the role of the posterior parietal cortex in supporting executive and lexical-semantic contributions to verbal episodic memory.

Posterior cortical atrophy: a single case cognitive and radiological follow-up

Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome characterized by initial predominant visuoperceptual deficits followed by a progressive decline in other cognitive functions. This syndrome has not been as thoroughly described as other dementias, particularly from a neuropsychological evolution perspective with only a few studies describing the evolution of its cognitive progression. In this investigation we review the literature on this rare condition and we perform a 7-year neuropsychological and neuroradiological follow-up of a 64-year-old man with PCA. The subject's deficits initially appeared in his visuoperceptual skills with later affectation appearing in language and other cognitive functions, this being coherent with the patient's parieto-temporal atrophy evolution.

Early-Onset Alzheimer Disease

Early-onset Alzheimer disease (EOAD), with onset in individuals younger than 65 years, although overshadowed by the more common late-onset AD (LOAD), differs significantly from LOAD. EOAD comprises approximately 5% of AD and is associated with delays in diagnosis, aggressive course, and age-related psychosocial needs. One source of confusion is that a substantial percentage of EOAD are phenotypic variants that differ from the usual memory-disordered presentation of typical AD. The management of EOAD is similar to that for LOAD, but special emphasis should be placed on targeting the specific cognitive areas involved and more age-appropriate psychosocial support and education.

Non-pharmacological intervention for posterior cortical atrophy

Posterior cortical atrophy (PCA) is a rare neurodegenerative condition characterized by progressive visual-perceptual deficits. Although the neurocognitive profile of PCA is a growing and relatively well-established field, non-pharmacological care remains understudied and to be widely established in clinical practice. In the present work we review the available literature on non-pharmacological approaches for PCA, such as cognitive rehabilitation including individual cognitive exercises and compensatory techniques to improve autonomy in daily life, and psycho-education aiming to inform people with PCA about the nature of their visual deficits and limits of cognitive rehabilitation. The reviewed studies represented a total of 7 patients. There is a scarcity of the number of studies, and mostly consisting of case studies. Results suggest non-pharmacological intervention to be a potentially beneficial approach for the partial compensation of deficits, improvement of daily functionality and improvement of quality of life. Clinical implications and future directions are also highlighted for the advancement of the field, in order to clarify the possible role of non-pharmacological interventions, and its extent, in PCA.

Spatial neglect in a patient with logopenic progressive aphasia

Spatial neglect and extinction are induced by posterior superior temporal and inferior parietal dysfunction. In patients with logopenic progressive aphasia (LPA) these structures are often degenerated, but there are no reports of these disorders being associated. A 53-year-old man with the signs of LPA revealed right-sided spatial neglect on line bisection and drawing tests as well as multimodal extinction. MRI showed left hemispheric posterior temporoparietal atrophy. Since injury to the core structures for these aphasic and attentional syndromes overlaps, patients with LPA should be screened for spatial neglect and extinction.

Autopsy-confirmed hippocampal-sparing Alzheimer's disease with delusional jealousy as initial manifestation

Alzheimer's disease (AD) is clinically characterized by gradual onset over years with worsening of cognition. The initial and most prominent cognitive deficit is commonly memory dysfunction. However, a subset of AD cases has less hippocampal atrophy than would be expected relative to the predominance of cortical atrophy. These hippocampal-sparing cases have distinctive clinical features, including the presence of focal cortical clinical syndromes. Given that previous studies have indicated that severe hippocampal atrophy corresponds to prominent loss of episodic memory, it is likely that memory impairment is initially absent in hippocampal-sparing AD cases. Here, we report on a patient with an 8-year history of delusional jealousy with insidious onset who was clinically diagnosed as possible AD and pathologically confirmed to have AD with relatively preserved neurons in the hippocampus. This patient had delusional jealousy with a long pre-dementia stage, which initially was characterized by lack of memory impairment. Head magnetic resonance imaging findings showed preserved hippocampal volume with bilateral enlarged ventricles and mild-to-moderate cortical atrophy. Head single-photon emission computed tomography revealed severely decreased regional cerebral blood flow in the right temporal lobe. The resolution of the delusion was attributed to pharmacotherapy by an acetylcholinesterase inhibitor, suggesting that the occurrence of delusional jealousy was due to the disease process of AD. Although the neural basis of delusional jealousy remains unclear, this hippocampal-sparing AD case may be classified as an atypical presentation of AD.

[Assessment of 10 years of memory consultations in the Franche-Comté: Description and analysis of the RAPID regional database]

The aim of this study was to evaluate the impact, on a regional scale (Franche-Comté), of 3 National Alzheimer care plans, particularly concerning the development of the offer of care management by clinicians as well as the panel of diagnoses concerned. Data on sociodemographic, neuropsychological and diagnostic characteristics were retrieved from the RAPID regional database between 1st January 2003 and 31st December 2012. These analyses focused exclusively on patients who had an initial consultation (n=12,017) during the same period. The existence of a previously established health network capable of carrying out governmental health plans has produced an effective interface between regional administrative structures responsible for the implementation of these plans and health professionals responsible for carrying out them out. This network study, the use of a battery of tests and a common software database have enabled the development of patient care management throughout the Franche-Comté region. It also showed the diversification of diagnoses mentioned over the past years as well as changes in clinical practices on how to address the issue of cognitive impairment.

CSF levels of Aβ1-38/Aβ1-40/Aβ1-42 and (11)C PiB-PET studies in three clinical variants of primary progressive aphasia and Alzheimer's disease

Primary progressive aphasia (PPA) is a cognitive syndrome characterized by progressive and isolated language impairments due to neurodegenerative diseases. Recently, an international group of experts published a Consensus Classification of the three PPA clinical variants (naPPA, svPPA and lvPPA). We analyzed 24 patients with PPA by cognitive functions, neuroimaging (MRI, (99 m)Tc ECD-SPECT, (11)C PiB-PET and FDG-PET) and cerebrospinal fluid (CSF) analysis (ptau-181, Aβ1-42, Aβ1-40 and Aβ1-38), to elucidate relationships between neuroimaging studies and biochemical findings in the three PPA clinical variants. Cognitive and speech functions were measured by mini-mental state examination and standard language test of aphasia. The patients with lvPPA showed significant decreases in CSF Aβ1-42 and ratios of Aβ1-42/Aβ1-40 and Aβ1-42/Aβ1-38, and significant increases in CSF ptau-181 and ratios of ptau-181/Aβ1-42 and ptau-181/Aβ1-38; these findings were similar to those of patients with Alzheimer's disease (AD). We observed a higher frequency of the ApoE ε4 allele in the lvPPA patients relative to the two other PPA variants. In (11)C PiB-PET of lvPPA patients, PiB positive findings were detected in cortices of frontal, temporal and parietal lobes and the posterior cingulate, where massive Aβ may accumulate due to AD. Our results of AD-CSF markers including Aβ1-38 and (11)C PiB-PET in the lvPPA patients demonstrate a common pathological mechanism with the occurrence of AD.

Posterior AD-type pathology: cognitive subtypes emerging from a cluster analysis

BACKGROUND

"Posterior shift" of the neuropathological changes of Alzheimer's disease (AD) produces a syndrome (posterior cortical atrophy) (PCA) dominated by high-level visual deficits.

OBJECTIVE

To explore in patients with AD-type pathology whether a data-driven analysis (cluster analysis) based on neuropsychological findings resulted in the emergence of different subgroups of patients; in particular to find out whether it was possible to identify patients with visuospatial deficits consistent with the hypothesis that PCA is a "dorsal stream" syndrome or, rather, whether there were subgroups of patients with different types of impairment within the high-level visual domain.

METHODS

23 PCA and 16 DAT patients were studied. By a principal component analysis performed on a wide range of neuropsychological tasks, 15 variables were obtained that loaded onto five main factors (memory, language, perceptual, visuospatial, and calculation) which entered a hierarchical cluster analysis.

RESULTS

Four clusters of cognitive impairment emerged: visuospatial/perceptual, memory, perceptual/calculation, and language. Only in the first cluster a visuospatial deficit clearly emerged. conclusions: AD pathology produces not only variants dominated by memory (DAT) and, to a lesser extent, visuospatial deficit (PCA), but also other distinct syndromic subtypes with disorders in visual perception and language which reflect a different vulnerability of specific functional networks.

Towards a clearer definition of logopenic progressive aphasia

Logopenic progressive aphasia is the most recently described clinical variant of primary progressive aphasia (PPA), defined by impairment of lexical retrieval and sentence repetition. Unlike other PPA variants, the logopenic variant of PPA (lv-PPA) is commonly associated with Alzheimer's disease (AD), a fact that is relevant to the selection of patients for clinical trials and disease-modifying therapies. Despite the straightforward definition and coherent pathological association, the existence of lv-PPA has been challenged, as its distinction from AD or other PPA variants can be difficult. Despite these issues, lv-PPA patients display characteristic linguistic deficits, a pattern of brain atrophy, and possibly genetic susceptibility, which warrant considering this variant as a discrete AD endophenotype. More specific clinical and anatomical markers can strengthen the consistency of this syndrome.