Keir X X Yong

Keir X X Yong
University College London | UCL · Institute of Neurology

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119
Publications
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2,233
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Publications

Publications (119)
Article
Full-text available
Background Responses to individualized music in people living with dementia can be indicated by both verbal and non‐verbal cues. Evidence suggests that elevated pupil dilation responses to familiar vs. unfamiliar music are preserved in people living with typical Alzheimer’s disease (tAD), and to an extent in people with its atypical ‘visual’ varian...
Article
Full-text available
Background Posterior cortical atrophy (PCA) is often considered the most common atypical Alzheimer’s disease phenotype, being characterized by progressive loss of visual and other posterior cortical functions. Early reading and other visuoperceptual difficulties prompt PCA patients presenting to eye clinics and receiving ocular misdiagnoses. Patien...
Article
Full-text available
Objective: Visual processing deficits arising in dementia are associated with particular functional disability. This study aimed to investigate the effects of the built environment on mobility and navigation in people with dementia-related visual loss. Methods: Participants with posterior cortical atrophy (PCA; “visual-variant Alzheimer’s”; n = 11)...
Article
Background and objectives: Alzheimer disease (AD) spans heterogeneous typical and atypical phenotypes. Posterior cortical atrophy (PCA) is a striking example, characterized by prominent impairment in visual and other posterior functions in contrast to typical, amnestic AD. The primary study objective was to establish how the similarities and diffe...
Article
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Background and purpose Logopenic variant primary progressive aphasia (lvPPA) is a major variant presentation of Alzheimer's disease (AD) that signals the importance of communication dysfunction across AD phenotypes. A clinical staging system is lacking for the evolution of AD‐associated communication difficulties that could guide diagnosis and care...
Article
Full-text available
Supporting ageing in place, quality of life, and activity engagement are public health priorities for people with dementia. The importance of maintaining opportunities for meaningful activities has been widely acknowledged for those with dementia in long-term care, but little is known about what makes activities meaningful for, and how they are exp...
Article
Background Music has gained more attention than other art forms as a potent tool in supporting cognitive, emotional and social functioning in dementia populations. Methods for measuring moment‐to‐moment responses ‐ rather than comparing pre‐ and post‐stimulus effects ‐ may enable tailoring of musical experiences for the individual. The current stud...
Article
Background Posterior cortical atrophy (PCA) is a neurodegenerative syndrome most commonly caused by Alzheimer’s disease (AD) and is often considered the most common atypical AD presentation. PCA is characterised by predominant visual rather than memory loss and occipito‐parietal/occipito‐temporal atrophy (‘visual‐spatial AD’). Characteristic visual...
Article
Background The cognitive organisation of working memory for nonverbal sounds and the unusual musical ability of absolute pitch is poorly understood. We recently had the opportunity to investigate this in a musician with absolute pitch who developed posterior cortical atrophy (PCA), the canonical ‘visual variant’ of Alzheimer’s disease. Method We s...
Article
Background Music has gained more attention than other art forms as a potent tool in supporting cognitive, emotional and social functioning in dementia populations. Methods for measuring moment‐to‐moment responses ‐ rather than comparing pre‐ and post‐stimulus effects ‐ may enable tailoring of musical experiences for the individual. The current stud...
Article
Full-text available
Background Posterior cortical atrophy (PCA) is a neurodegenerative syndrome most commonly caused by Alzheimer’s disease (AD) pathology. PCA is often considered the canonical ‘visual dementia’, characterised by the progressive loss of visual and posterior cortical functions corresponding to parieto‐occipital and occipito‐temporal atrophy. However, p...
Article
Full-text available
INTRODUCTION Delay in diagnosis of posterior cortical atrophy (PCA) syndrome is common, and the lack of familiarity with assessment tools for identifying visual cortical dysfunction is a contributing factor. We propose recommendations for the approach to the evaluation of PCA clinical features during the office visit, the neuropsychological evaluat...
Article
Full-text available
INTRODUCTION Here we set out to create a symptom‐led staging system for the canonical semantic and non‐fluent/agrammatic variants of primary progressive aphasia (PPA), which present unique diagnostic and management challenges not well captured by functional scales developed for Alzheimer's disease and other dementias. METHODS An international PPA...
Article
Full-text available
Background and Objectives Alzheimer’s Disease (AD) is highly heterogeneous, with marked individual differences in clinical presentation and neurobiology. To explore this, we employed neuroanatomical normative modelling to index regional patterns of variability in cortical thickness. We aimed to characterise individual differences and outliers in co...
Article
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Introduction Visual processing deficits in Alzheimer's disease are associated with diminished functional independence. While environmental adaptations have been proposed to promote independence, recent guidance gives limited consideration to such deficits and offers conflicting recommendations for people with dementia. We evaluated the effects of c...
Article
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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...
Preprint
Full-text available
Alzheimer’s disease spans a heterogeneous collection of typical and atypical phenotypes. Posterior cortical atrophy represents one of the most striking examples, characterised by prominent impairment in visual and other posterior functions in contrast to typical, predominantly amnestic Alzheimer’s disease. Whilst proposed posterior cortical atrophy...
Conference Paper
Posterior cortical atrophy (PCA) is a clinically defined syndrome characterized by impairment in higher‐order visual processing. The underlying pathology in PCA is most commonly Alzheimer’s disease (AD), but large‐scale biomarker and neuropathological studies are lacking. In this ongoing project we aim to describe demographic, clinical, biomarker a...
Article
Posterior cortical atrophy (PCA) is a neurodegenerative, predominantly young‐onset syndrome most commonly caused by Alzheimer’s disease (AD). PCA presents with visual and spatial dysfunction attributed to occipito‐parietal or “posterior” brain regions rather than memory difficulties characteristic of typical Alzheimer’s disease (tAD) attributed to...
Article
Full-text available
Posterior Cortical Atrophy is a rare but significant form of dementia which affects peoples’ visual ability before their memory. This is often misdiagnosed as an eyesight rather than brain sight problem. This paper aims to address the frequent, initial misdiagnosis of this disease as a vision problem through the use of an intelligent, cost-effectiv...
Article
Full-text available
There is increasing theoretical and empirical support for the brain combining multisensory information to determine the direction of gravity and hence uprightness. A fundamental part of the process is the spatial transformation of sensory signals between reference frames: eye‐centred, head‐centred, body‐centred, etc. The question ‘Am I the right wa...
Article
Background Posterior cortical atrophy (PCA) is a clinico‐radiological syndrome mostly commonly underpinned by Alzheimer’s disease (AD) pathology and has been referred to as the most common atypical AD clinical phenotype. PCA consensus classification criteria emphasize core clinical and cognitive features comprising visual and other posterior featur...
Article
Introduction Sporadic inclusion body myositis (IBM) is a degenerative and inflammatory acquired myopathy characterised by muscle deposition of various proteins typically associated with Alzheimer's disease and other neurodegenerative diseases. While cognitive impairment is not noted as a clinical feature of IBM, evidence is lacking. We aimed to inv...
Article
Full-text available
Background: Posterior cortical atrophy (PCA) is the most common atypical variant of Alzheimer's disease (AD). Changes associated with PCA in the brain affect the visual cortex, but little is known about retinal changes in PCA. In this study, we explored retinal phenotypic variations in typical AD (tAD) and PCA. Methods: Retinal phenotyping was c...
Article
Full-text available
The basis of visual short-term memory (VSTM) impairments in preclinical Alzheimer’s disease (AD) remains unclear. Research suggests that eye movements may serve as indirect surrogates to investigate VSTM. Yet, investigations in preclinical populations are lacking. Fifty-two individuals from a familial Alzheimer’s disease (FAD) cohort (9 symptomatic...
Article
Most patients with Alzheimer's disease present with amnestic problems; however, a substantial proportion, over-represented in young-onset cases, have atypical phenotypes including predominant visual, language, executive, behavioural, or motor dysfunction. In the past, these individuals often received a late diagnosis; however, availability of CSF a...
Article
Full-text available
Recent data-sharing initiatives of clinical and preclinical Alzheimer’s disease (AD) have led to a growing number of non-clinical researchers analyzing these datasets using modern data-driven computational methods. Cognitive tests are key components of such datasets, representing the principal clinical tool to establish phenotypes and monitor sympt...
Article
Background Eye‐tracking technology is an innovative tool that holds promise for enhanced dementia screening, offering the potential of brief and quantitative assessment of cognitive functions. Critically, instruction‐less eye‐tracking tests may ameliorate some of the issues with complex test instructions and linguistic variations associated with tr...
Article
Background Eye‐tracking technology is an innovative tool that holds promise for enhanced dementia screening, offering the potential of brief and quantitative assessment of cognitive functions. Critically, instruction‐less eye‐tracking tests may ameliorate some of the issues with complex test instructions and linguistic variations associated with tr...
Chapter
Posterior cortical atrophy (PCA) is a neurodegenerative syndrome most commonly caused by Alzheimer’s disease (AD). PCA is a sporadic disorder, typically with onset between the ages of 50 and 65. The most prominent features of PCA are the early, progressive loss of vision and other posterior functions, in contrast to relatively preserved episodic me...
Article
Full-text available
Introduction: Clinical reports describe patients with Alzheimer's disease (AD) exhibiting atypical adaptive walking responses to the visual environment; however, there is limited empirical investigation of such behaviors or factors modulating their expression. We aim to evaluate effects of lighting-based interventions and clinical presentation (vi...
Article
Full-text available
Although posterior cortical atrophy is often regarded as the canonical 'visual dementia', auditory symptoms may also be salient in this disorder. Patients often report particular difficulty hearing in busy environments; however, the core cognitive process-parsing of the auditory environment ('auditory scene analysis')-has been poorly characterized....
Article
Full-text available
Eye-tracking technology is an innovative tool that holds promise for enhancing dementia screening. In this work, we introduce a novel way of extracting salient features directly from the raw eye-tracking data of a mixed sample of dementia patients during a novel instruction-less cognitive test. Our approach is based on self-supervised representatio...
Article
Full-text available
Introduction: This work aims to characterize the sequence in which cognitive deficits appear in two dementia syndromes. Methods: Event-based modeling estimated fine-grained sequences of cognitive decline in clinically-diagnosed posterior cortical atrophy (PCA) ( n = 94 ) and typical Alzheimer's disease (tAD) ( n = 61 ) at the UCL Dementia...
Chapter
Full-text available
We introduce Disease Knowledge Transfer (DKT), a novel technique for transferring biomarker information between related neurodegenerative diseases. DKT infers robust multimodal biomarker trajectories in rare neurodegenerative diseases even when only limited, unimodal data is available, by transferring information from larger multimodal datasets fro...
Book
Full-text available
We introduce Disease Knowledge Transfer (DKT), a novel technique for transferring biomarker information between related neurodegenerative diseases. DKT infers robust multimodal biomarker trajectories in rare neurodegenerative diseases even when only limited, unimodal data is available, by transferring information from larger multimodal datasets fro...
Article
Full-text available
Background: Progressive reading impairment is an early and debilitating symptom of posterior cortical atrophy (PCA) arising from the progressive deterioration of visual processing skills. Objective: The goal of this study was to test the effectiveness of a purpose-built reading app (ReadClear) co-produced with people living with PCA and designed...
Article
Full-text available
Background: Retinal thickness can be measured non-invasively with optical coherence tomography (OCT) and may offer compelling potential as a biomarker for Alzheimer's disease (AD). Retinal thinning is hypothesized to be a result of retrograde atrophy and/or parallel neurodegenerative processes. Changes in the visual pathway are of particular inter...
Article
Full-text available
Posterior cortical atrophy is a clinico-radiological syndrome characterized by progressive decline in visual processing and atrophy of posterior brain regions. With the majority of cases attributable to Alzheimer’s disease and recent evidence for genetic risk factors specifically related to posterior cortical atrophy, the syndrome can provide impor...
Article
Full-text available
Posterior cortical atrophy (PCA) is a degenerative condition characterized by a progressive deterioration of visual processing. Dyslexia constitutes an early and frequent visual symptom of the disease and previous comprehensive investigations in series of individuals have extensively documented a characteristic abundance of visual errors as the mos...
Article
Full-text available
People with Alzheimer’s disease (AD) have characteristic problems navigating everyday environments. While patients may exhibit abnormal gait parameters, adaptive gait irregularities when navigating environments are little explored or understood. The aim of this study was to assess adaptive locomotor responses of AD subjects in a complex environment...
Article
Full-text available
It has been highlighted that health and social care staff need a greater awareness of the needs and problems of those people with young onset dementia in the UK. Symptoms of Alzheimer's disease are relatively well known (memory loss, disorientation, language difficulties and behavioural problems). However, there is less awareness of dementia‐relate...
Preprint
Full-text available
We introduce Disease Knowledge Transfer (DKT), a novel technique for transferring biomarker information between related neurodegenerative diseases. DKT infers robust multimodal biomarker trajectories in rare neurodegenerative diseases even when only limited, unimodal data is available, by transferring information from larger multimodal datasets fro...
Conference Paper
Full-text available
We introduce Disease Knowledge Transfer (DKT), a novel technique for transferring biomarker information between related neurodegenerative diseases. DKT infers robust multimodal biomarker trajectories in rare neurodegenerative diseases even when only limited, unimodal data is available, by transferring information from larger multimodal datasets fro...
Data
Influence of APOE genotype on hippocampal subfield volumes in EOAD patients. Key: APOE ε4 +ve = APOE ε4 positive; APOE ε4 -ve = APOE ε4 negative; tAD=amnestic led typical Alzheimer’s disease; PCA=posterior cortical atrophy; TIV=total intracranial volume; GCMLDG=Molecular and Granule Cell Layers of the Dentate Gyrus; HATA=Hippocampal Amygdala Transi...
Article
Full-text available
The most common presentation of early onset Alzheimer's disease (EOAD – defined as symptom onset <65 years) is with progressive episodic memory impairment – amnestic or typical Alzheimer's disease (tAD). However, EOAD is notable for its phenotypic heterogeneity, with posterior cortical atrophy (PCA) – characterised by prominent higher-order visual...
Article
Full-text available
The current report describes the journey from the sharing of a single, extraordinary experience during a support group conversation to the development of a novel scientific investigation of balance problems in a rarer form of dementia. The story centres around the involvement of people living with or caring for someone with posterior cortical atrop...
Article
Deficits in spatial navigation are characteristic and disabling features of typical Alzheimer's disease (tAD) and posterior cortical atrophy (PCA). Visual cues have been proposed to mitigate such deficits; however, there is currently little empirical evidence for their use. The effect of visual cues on visually guided navigation was assessed within...
Data
Table S1. Proportion of trials completed within the cut‐off time of 60 sec under baseline and cue conditions for tAD, PCA, combined patient group and controls.
Article
Full-text available
Dementia is characterised by its progressive degeneration of cognitive abilities. In research cohorts, detailed neuropsychological test batteries are often administered to better understand how cognition changes over time. Understanding cognitive changes in dementia is of great importance, particularly in determining how structural changes in the b...
Preprint
Full-text available
Dementia is characterised by its progressive degeneration of cognitive abilities. In research cohorts, detailed neuropsychological test batteries are often administered to better understand how cognition changes over time. Understanding cognitive changes in dementia is of great importance, particularly in determining how structural changes in the b...
Article
Full-text available
Objectives To explore the stress process for individuals living with posterior cortical atrophy (PCA) and their families. Design A qualitative study using in-depth semi-structured dyadic and individual interviews with people living with a diagnosis of PCA and a family carer. Interview transcripts were thematically analysed. Setting Participants’...
Article
Full-text available
Objective Deficits in spatial navigation are characteristic and disabling features of typical Alzheimer's disease (tAD) and posterior cortical atrophy (PCA). Visual cues have been proposed to mitigate such deficits; however, there is currently little empirical evidence for their use. Methods The effect of visual cues on visually guided navigation...
Article
Full-text available
Eyetracking technology has had limited application in the dementia field to date, with most studies attempting to discriminate syndrome subgroups on the basis of basic oculomotor functions rather than higher-order cognitive abilities. Eyetracking-based tasks may also offer opportunities to reduce or ameliorate problems associated with standard pape...
Article
Full-text available
Young onset Alzheimer’s disease (YOAD) is defined as symptom onset before the age of 65 years and is particularly associated with phenotypic heterogeneity. Atypical presentations, such as the clinic-radiological visual syndrome posterior cortical atrophy (PCA), often lead to delays in accurate diagnosis. Eyetracking has been used to demonstrate bas...
Article
This poster reports on a study of brainsight in Alzheimer’s disease (AD), integrating findings from three preparatory studies lead by neuropsychologists, engineers and social scientists. The work relies on unique insights offered by those with Posterior Cortical Atrophy (PCA) – a rare dementia usually caused by AD, but characterised by early, progr...
Article
Full-text available
Introduction: A classification framework for posterior cortical atrophy (PCA) is proposed to improve the uniformity of definition of the syndrome in a variety of research settings. Methods: Consensus statements about PCA were developed through a detailed literature review, the formation of an international multidisciplinary working party which c...
Article
Spelling is a complex cognitive task where central and peripheral components are involved in engaging resources from many different cognitive processes. The present paper aims to both characterize the oral spelling deficit in a population of patients affected by a neurodegenerative condition and to clarify the nature of the graphemic representation...
Article
Posterior cortical atrophy (PCA) is the canonical “visual dementia,” with affected individuals experiencing a progressive disintegration of their visual world owing to dysfunction and atrophy at the back of the brain. The syndrome, which also affects literacy, numeracy, and gesture, is typically caused by Alzheimer’s disease, but is distinguished f...