Diagnostic evaluation and monitoring of patients with posterior cortical atrophy

Pisa Syndrome Secondary to Drugs: A Scope Review

BACKGROUND

Pisa syndrome, also known as pleurothotonus, is a neurological condition characterized by more than ten degrees of constant lateral curvature of the spine when upright. In this way, the present manuscript aims to systematically review Pisa syndrome secondary to drugs.

METHODS

Two reviewers identified and assessed relevant reports in six databases without language restriction between January 1990 and June 2024.

RESULTS

The prevalence of Pisa syndrome varied from 0.037 to 9.3%. We found 109 articles containing 191 cases of drug-induced Pisa syndrome reported in the literature. The mean and median ages were 59.70 (SD = 19.02) and 67 (range = 12-98 years). The most prevalent sex was female, 56.91% (107/188). The most frequent medications associated with Pisa syndrome were acetylcholinesterase inhibitors in 87 individuals. Of 112 individuals in which the onset time from the medication to the movement disorder occurrence was reported, 59 took place within a month. In this way, a return to baseline was observed in 45.50% of the cases, and partial recovery was observed in 14.28%.

CONCLUSION

We proposed new diagnostic criteria for Pisa syndrome based on previous findings in the literature. Moreover, multiple mechanisms are probably involved in balance control and the development of lateral trunk flexions.

Language uncovers visuospatial dysfunction in posterior cortical atrophy: a natural language processing approach

Introduction

Posterior Cortical Atrophy (PCA) is a syndrome characterized by a progressive decline in higher-order visuospatial processing, leading to symptoms such as space perception deficit, simultanagnosia, and object perception impairment. While PCA is primarily known for its impact on visuospatial abilities, recent studies have documented language abnormalities in PCA patients. This study aims to delineate the nature and origin of language impairments in PCA, hypothesizing that language deficits reflect the visuospatial processing impairments of the disease.

Methods

We compared the language samples of 25 patients with PCA with age-matched cognitively normal (CN) individuals across two distinct tasks: a visually-dependent picture description and a visually-independent job description task. We extracted word frequency, word utterance latency, and spatial relational words for this comparison. We then conducted an in-depth analysis of the language used in the picture description task to identify specific linguistic indicators that reflect the visuospatial processing deficits of PCA.

Results

Patients with PCA showed significant language deficits in the visually-dependent task, characterized by higher word frequency, prolonged utterance latency, and fewer spatial relational words, but not in the visually-independent task. An in-depth analysis of the picture description task further showed that PCA patients struggled to identify certain visual elements as well as the overall theme of the picture. A predictive model based on these language features distinguished PCA patients from CN individuals with high classification accuracy.

Discussion

The findings indicate that language is a sensitive behavioral construct to detect visuospatial processing abnormalities of PCA. These insights offer theoretical and clinical avenues for understanding and managing PCA, underscoring language as a crucial marker for the visuospatial deficits of this atypical variant of Alzheimer's disease.

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.

Language Uncovers Visuospatial Dysfunction in Posterior Cortical Atrophy: A Natural Language Processing Approach

Introduction

Posterior Cortical Atrophy (PCA) is a syndrome characterized by a progressive decline in higher-order visuospatial processing, leading to symptoms such as space perception deficit, simultanagnosia, and object perception impairment. While PCA is primarily known for its impact on visuospatial abilities, recent studies have documented language abnormalities in PCA patients. This study aims to delineate the nature and origin of language impairments in PCA, hypothesizing that language deficits reflect the visuospatial processing impairments of the disease.

Methods

We compared the language samples of 25 patients with PCA with age-matched cognitively normal (CN) individuals across two distinct tasks: a visually-dependent picture description and a visually-independent job description task. We extracted word frequency, word utterance latency, and spatial relational words for this comparison. We then conducted an in-depth analysis of the language used in the picture description task to identify specific linguistic indicators that reflect the visuospatial processing deficits of PCA.

Results

Patients with PCA showed significant language deficits in the visually-dependent task, characterized by higher word frequency, prolonged utterance latency, and fewer spatial relational words, but not in the visually-independent task. An in-depth analysis of the picture description task further showed that PCA patients struggled to identify certain visual elements as well as the overall theme of the picture. A predictive model based on these language features distinguished PCA patients from CN individuals with high classification accuracy.

Discussion

The findings indicate that language is a sensitive behavioral construct to detect visuospatial processing abnormalities of PCA. These insights offer theoretical and clinical avenues for understanding and managing PCA, underscoring language as a crucial marker for the visuospatial deficits of this atypical variant of Alzheimer's disease.

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.

Anterior dorsal attention network tau drives visual attention deficits in posterior cortical atrophy

Posterior cortical atrophy (PCA), usually an atypical clinical syndrome of Alzheimer's disease, has well-characterized patterns of cortical atrophy and tau deposition that are distinct from typical amnestic presentations of Alzheimer's disease. However, the mechanisms underlying the cortical spread of tau in PCA remain unclear. Here, in a sample of 17 biomarker-confirmed (A+/T+/N+) individuals with PCA, we sought to identify functional networks with heightened vulnerability to tau pathology by examining the cortical distribution of elevated tau as measured by 18F-flortaucipir (FTP) PET. We then assessed the relationship between network-specific FTP uptake and visuospatial cognitive task performance. As predicted, we found consistent and prominent localization of tau pathology in the dorsal attention network and visual network of the cerebral cortex. Elevated FTP uptake within the dorsal attention network (particularly the ratio of FTP uptake between the anterior and posterior nodes) was associated with poorer visuospatial attention in PCA; associations were also identified in other functional networks, although to a weaker degree. Furthermore, using functional MRI data collected from each patient at wakeful rest, we found that a greater anterior-to-posterior ratio in FTP uptake was associated with stronger intrinsic functional connectivity between anterior and posterior nodes of the dorsal attention network. Taken together, we conclude that our cross-sectional marker of anterior-to-posterior FTP ratio could indicate tau propagation from posterior to anterior dorsal attention network nodes, and that this anterior progression occurs in relation to intrinsic functional connectivity within this network critical for visuospatial attention. Our findings help to clarify the spatiotemporal pattern of tau propagation in relation to visuospatial cognitive decline and highlight the key role of the dorsal attention network in the disease progression of PCA.

Gray to white matter signal ratio as a novel biomarker of neurodegeneration in Alzheimer's disease

Alzheimer's disease (AD) is characterized neuropathologically by β-amyloid (Aβ) plaques, hyperphosphorylated tau neurofibrillary tangles, and neurodegeneration, which lead to a phenotypically heterogeneous cognitive-behavioral dementia syndrome. Our understanding of how these neuropathological and neurodegeneration biomarkers relate to each other is still evolving. A relatively new approach to measuring structural brain change, gray matter to white matter signal intensity ratio (GWR), quantifies the signal contrast between these tissue compartments, and has emerged as a promising marker of AD-related neurodegeneration. We sought to validate GWR as a novel MRI biomarker of neurodegeneration in 29 biomarker positive individuals across the atypical syndromic spectrum of AD. Bivariate correlation analyses revealed that GWR was associated with cortical thickness, tau PET, and amyloid PET, with GWR showing a larger magnitude of abnormality than cortical thickness. We also found that combining GWR, cortical thickness, and amyloid PET better explained observed tau PET signal than using these modalities alone, suggesting that the three imaging biomarkers contribute independently and synergistically to explaining the variance in the distribution of tau pathology. We conclude that GWR is a uniquely sensitive in vivo marker of neurodegenerative change that reflects pathological mechanisms which may occur prior to cortical atrophy. By using all of these imaging biomarkers of AD together, we may be better able to capture, and possibly predict, AD neuropathologic changes in vivo. We hope that such an approach will ultimately contribute to better endpoints to evaluate the efficacy of therapeutic interventions as we move toward an era of disease-modifying treatments for this devastating disease.

Development of the Colorado posterior cortical questionnaire within an Alzheimer's disease study cohort

INTRODUCTION

Non-amnestic presentations of neurodegenerative dementias, including posterior- and visual-predominant cognitive forms, are under-recognized. Specific screening measures for posterior cortical symptoms could allow for earlier, more accurate diagnosis and directed treatment.

METHODS

Based on clinical experience with posterior cortical atrophy evaluations, high-yield screening questions were collected and organized into a 15-item self-report questionnaire, titled the Colorado Posterior Cortical Questionnaire (CPC-Q). The CPC-Q was then piloted within a longitudinal cohort of cognitive aging, including 63 older adults, including healthy older adults (n = 33) and adults with either amnestic Alzheimer's disease (n = 21) or posterior cortical atrophy (PCA, n = 9).

RESULTS

The CPC-Q demonstrated acceptable psychometric properties (internal consistency, α = 0.89; mean item-total correlation = 0.62), correlated strongly with visuospatial measures on cognitive testing (p < 0.001), and could distinguish PCA from non-PCA groups (p < 0.001; AUC 0.95 (95% CI 0.88, 1.0)).

CONCLUSIONS

The CPC-Q captured posterior cortical symptoms in older adults, using a gold standard of expert consensus PCA diagnosis. Future studies will validate the CPC-Q in a larger cohort, with recruitment of additional PCA participants, to evaluate its convergent and discriminant validity more thoroughly. As a short, self-report tool, the CPC-Q demonstrates potential to improve detection of non-amnestic neurodegenerative dementias in the clinical setting.

Verbal Encoding Deficits Impact Recognition Memory in Atypical “Non-Amnestic” Alzheimer’s Disease

Memory encoding and retrieval deficits have been identified in atypical Alzheimer’s disease (AD), including posterior cortical atrophy (PCA) and logopenic variant primary progressive aphasia (lvPPA), despite these groups being referred to as “non-amnestic”. There is a critical need to better understand recognition memory in atypical AD. We investigated performance on the California Verbal Learning Test (CVLT-II-SF) in 23 amyloid-positive, tau-positive, and neurodegeneration-positive participants with atypical “non-amnestic” variants of AD (14 PCA, 9 lvPPA) and 14 amnestic AD participants. Recognition memory performance was poor across AD subgroups but trended toward worse in the amnestic group. Encoding was related to recognition memory in non-amnestic but not in amnestic AD. We also observed cortical atrophy in dissociable subregions of the distributed memory network related to encoding (left middle temporal and angular gyri, posterior cingulate and precuneus) compared to recognition memory (anterior medial temporal cortex). We conclude that recognition memory is not spared in all patients with atypical variants of AD traditionally thought to be “non-amnestic”. The non-amnestic AD patients with poor recognition memory were those who struggled to encode the material during the learning trials. In contrast, the amnestic AD group had poor recognition memory regardless of encoding ability.

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.

Clinical application of CSF biomarkers for Alzheimer's disease: From rationale to ratios

Biomarker testing is recommended for the accurate and timely diagnosis of Alzheimer's disease (AD). Using illustrative case narratives we consider how cerebrospinal fluid (CSF) biomarker tests may be used in different presentations of cognitive impairment to facilitate timely and differential diagnosis, improving diagnostic accuracy, providing prognostic information, and guiding personalized management in diverse scenarios. Evidence shows that (1) CSF ratios are superior to amyloid beta (Aβ)1-42 alone; (2) concordance of CSF ratios to amyloid positron emission tomography (PET) is better than Aβ1-42 alone; and (3) phosphorylated tau (p-tau)/Aβ1-42 ratio is superior to p-tau alone. CSF biomarkers are recommended for the exclusion of AD as the underlying cause of cognitive impairment, diagnosis of AD at an early stage, differential diagnosis of AD in individuals presenting with other neuropsychiatric symptoms, accurate diagnosis of AD in an atypical presentation, and for clinical trial enrichment.

Highlights

 Cerebrospinal fluid (CSF) Alzheimer's disease (AD) biomarker testing may be underused outside specialist centers.CSF biomarkers improve diagnostic accuracy, guiding personalized management of AD.CSF ratios (amyloid beta [Aβ]1-42/Aβ1-40 and phosphorylated tau/Aβ1-42) perform better than single markers.CSF ratios produce fewer false-negative and false-positive results than individual markers.CSF biomarkers should be included in diagnostic work-up of AD and mild cognitive impairment due to AD.

Outdoor green space exposure and brain health measures related to Alzheimer's disease: a rapid review

OBJECTIVES

Summarise studies of outdoor green space exposure and brain health measures related to Alzheimer's disease and related disorders (ADRD), and determine scientific gaps for future research.

DESIGN

Rapid review of primary research studies.

METHODS AND OUTCOMES

PubMed, Embase and Web of Science Core Collection were searched for articles meeting the criteria published on/before 13 February 2020. The review excluded papers not in English, focused on transient states (eg, mental fatigue) or not using individual-level measures of brain health (eg, average school test scores). Brain health measures of interest included cognitive function, clinical diagnosis of cognitive impairment/dementia/ADRD and brain biomarkers such as those from MRI, measures typically associated with ADRD risk and disease progression.

RESULTS

Twenty-two papers were published from 2012 to 2020, 36% on <18 years old, 32% on 18-64 years old and 59% on ≥65 years old. Sixty-four per cent defined green space based on the Normalised Difference Vegetation Index ('greenness'/healthy vegetation) and 68% focused on cognitive measures of brain health (eg, memory). Seventeen studies (77%) found green space-brain health associations (14 positive, 4 inverse). Greater greenness/green space was positively associated various cognitive domains in 10 studies and with MRI outcomes (regional brain volumes, cortical thickness, amygdala integrity) in three studies. Greater neighbourhood greenness was associated with lower odds/risk of cognitive impairment/ADRD in some studies but increased odds/risk in others (n=4 studies).

CONCLUSIONS

Published studies suggest positive green space-brain health associations across the life course, but the methods and cohorts were limited and heterogeneous. Future research using racially/ethnically and geographically diverse cohorts, life course methods and more specific green space and brain health measures (eg, time spent in green spaces, ADRD biomarkers) will strengthen evidence for causal associations.

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.

In It Together: A Qualitative Meta-Synthesis of Common and Unique Psychosocial Stressors and Adaptive Coping Strategies of Persons With Young-Onset Dementia and Their Caregivers

BACKGROUND AND OBJECTIVES

The common and unique psychosocial stressors and adaptive coping strategies of people with young-onset dementia (PWDs) and their caregivers (CGs) are poorly understood. This meta-synthesis used the stress and coping framework to integrate and organize qualitative data on the common and unique psychosocial stressors and adaptive coping strategies employed by PWDs and CGs after a diagnosis of young-onset dementia (YOD).

RESEARCH DESIGN AND METHODS

Five electronic databases were searched for qualitative articles from inception to January 2020. Qualitative data were extracted from included articles and synthesized across articles using taxonomic analysis.

RESULTS

A total of 486 articles were obtained through the database and hand searches, and 322 articles were screened after the removal of duplicates. Sixty studies met eligibility criteria and are included in this meta-synthesis. Four themes emerged through meta-synthesis: 1) common psychosocial stressors experienced by both PWDs and CGs, 2) unique psychosocial stressors experienced by either PWDs or CGs, 3) common adaptive coping strategies employed by both PWDs and CGs, and 4) unique adaptive coping strategies employed by either PWDs or CGs. Within each meta-synthesis theme, subthemes pertaining to PWDs, CGs, and dyads (i.e., PWD and CG as a unit) emerged.

DISCUSSION AND IMPLICATIONS

The majority of stressors and adaptive coping strategies of PWDs and CGs were common, supporting the use of dyadic frameworks to understand the YOD experience. Findings directly inform the development of resiliency skills interventions to promote adaptive coping in the face of a YOD diagnosis for both PWDs and CGs.

Pisa syndrome induced by switching of a choline-esterase inhibitor treatment from donepezil to galantamine: a case report

Background

Pisa syndrome (PS) is characterized by an abnormally sustained posture, with flexion of the body and head to one side and slight rotation of the trunk. Although PS most commonly arises as an adverse effect of antipsychotic drugs, choline-esterase inhibitors (ChEIs) are also sometimes known to induce PS. Despite the fact that the precise mechanism remains unclear, cholinergic-dopaminergic imbalance has been considered as a possible pathophysiologic mechanism underlying the genesis of PS.

Case presentation

We hereby report the case of a 60-year-old woman with Alzheimer’s disease who presented with the signs of PS after her treatment was switched to galantamine, a type of ChEI, even though she had received donepezil, another type of ChEI, for 5 years without any complications. To the best of our knowledge, this is the first report of PS associated with treatment switch from one to another type of ChEI. Galantamine, but not other ChEIs, can enhance striatal dopamine release through allosteric modulation of the nicotinic acetylcholine receptor, and has weaker muscarinic effects than donepezil. Therefore, we propose two novel hypotheses to explain the development of PS, as follows; galantamine, which enhances dopamine release, can induce imbalance of dopamine levels in the striatum of patients with dementia, resulting in PS, and the weaker muscarinic effects of the drug could be one of the factors predisposing to the development of PS.

Conclusion

The present case suggests that treatment with galantamine is associated with a higher risk of development of PS than that with other ChEIs, such as donepezil, despite the pharmacological profile of galantamine as a dopamine modulator. Also, this report provides novel insight into another plausible mechanism underlying the development of PS, besides cholinergic-dopaminergic imbalance, namely, dopamine imbalance in the striatum with muscarinic-nicotinic imbalance.

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.