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A neuroimaging-based biomarker termed the brain age is thought to reflect variability in the brain's ageing process and predict longevity. Using Insight 46, a unique narrow-age birth cohort, we aimed to examine potential drivers and correlates of brain age.Participants, born in a single week in 1946 in mainland Britain, have had 24 prospective waves of data collection to date, including MRI and amyloid PET imaging at approximately 70 years old. Using MRI data from a previously defined selection of this cohort, we derived brain-predicted age from an established machine-learning model (trained on 2001 healthy adults aged 18-90 years); subtracting this from chronological age (at time of assessment) gave the brain-predicted age difference (brain-PAD). We tested associations with data from early life, midlife, and late life, as well as rates of MRI-derived brain atrophy.Between May 28, 2015, and Jan 10, 2018, 502 individuals were assessed as part of Insight 46. We included 456 participants (225 female), with a mean chronological age of 70·7 years (SD 0·7; range 69·2 to 71·9). The mean brain-predicted age was 67·9 years (8·2, 46·3 to 94·3). Female sex was associated with a 5·4-year (95% CI 4·1 to 6·8) younger brain-PAD than male sex. An increase in brain-PAD was associated with increased cardiovascular risk at age 36 years (β=2·3 [95% CI 1·5 to 3·0]) and 69 years (β=2·6 [1·9 to 3·3]); increased cerebrovascular disease burden (1·9 [1·3 to 2·6]); lower cognitive performance (-1·3 [-2·4 to -0·2]); and increased serum neurofilament light concentration (1·2 [0·6 to 1·9]). Higher brain-PAD was associated with future hippocampal atrophy over the subsequent 2 years (0·003 mL/year [0·000 to 0·006] per 5-year increment in brain-PAD). Early-life factors did not relate to brain-PAD. Combining 12 metrics in a hierarchical partitioning model explained 33% of the variance in brain-PAD.Brain-PAD was associated with cardiovascular risk, and imaging and biochemical markers of neurodegeneration. These findings support brain-PAD as an integrative summary metric of brain health, reflecting multiple contributions to pathological brain ageing, and which might have prognostic utility.Alzheimer's Research UK, Medical Research Council Dementia Platforms UK, Selfridges Group Foundation, Wolfson Foundation, Wellcome Trust, Brain Research UK, Alzheimer's Association.

ObjectiveTo investigate subjective cognitive decline (SCD) in relation to β-amyloid pathology and to test for associations with anxiety, depression, objective cognition and family history of dementia in the Insight 46 study.MethodsCognitively unimpaired ~70-year-old participants, all born in the same week in 1946 (n=460, 49% female, 18% amyloid-positive), underwent assessments including the SCD-Questionnaire (MyCog). MyCog scores were evaluated with respect to18F-Florbetapir-PET amyloid status (positive/negative). Associations with anxiety, depression, objective cognition (measured by the Preclinical Alzheimer Cognitive Composite, PACC) and family history of dementia were also investigated. The informant’s perspective on SCD was evaluated in relation to MyCog score.ResultsAnxiety (mean (SD) trait anxiety score: 4.4 (3.9)) was associated with higher MyCog scores, especially in women. MyCog scores were higher in amyloid-positive compared with amyloid-negative individuals (adjusted means (95% CIs): 5.3 (4.4 to 6.1) vs 4.3 (3.9 to 4.7), p=0.044), after accounting for differences in anxiety. PACC (mean (SD) −0.05 (0.68)) and family history of dementia (prevalence: 23.9%) were not independently associated with MyCog scores. The informant’s perception of SCD was generally in accordance with that of the participant.ConclusionsThis cross-sectional study demonstrates that symptoms of SCD are associated with both β-amyloid pathology, and more consistently, trait anxiety in a population-based cohort of older adults, at an age when those who are destined to develop dementia are still likely to be some years away from symptoms. This highlights the necessity of considering anxiety symptoms when assessing Alzheimer’s disease pathology and SCD.

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 representation learning where, by training initially a deep neural network to solve a pretext task using well-defined available labels (e.g. recognising distinct cognitive activities in healthy individuals), the network encodes high-level semantic information which is useful for solving other problems of interest (e.g. dementia classification). Inspired by previous work in explainable AI, we use the Layer-wise Relevance Propagation (LRP) technique to describe our network's decisions in differentiating between the distinct cognitive activities. The extent to which eye-tracking features of dementia patients deviate from healthy behaviour is then explored, followed by a comparison between self-supervised and handcrafted representations on discriminating between participants with and without dementia. Our findings not only reveal novel self-supervised learning features that are more sensitive than handcrafted features in detecting performance differences between participants with and without dementia across a variety of tasks, but also validate that instruction-less eye-tracking tests can detect oculomotor biomarkers of dementia-related cognitive dysfunction. This work highlights the contribution of self-supervised representation learning techniques in biomedical applications where the small number of patients, the non-homogenous presentations of the disease and the complexity of the setting can be a challenge using state-of-the-art feature extraction methods.

Objective: Simultanagnosia, a deficit in holistic visual perception, is among the most prominent features of posterior cortical atrophy (PCA). Deficits in visuoperceptual and attentional mechanisms could contribute to simultanagnosia. In the present study, we explored the impaired visual perception of global configuration with two main hypotheses: (a) It is due to a deficit in processing low-spatial frequency stimuli, and (b) it arises from deficits in adjusting attentional focus. Method: The visuoperceptual mechanism was explored by asking participants (5 PCA patients and 20 age- and education-matched healthy controls) to report the local and global elements of incongruent hierarchical letters. Stimuli were unbiased (black letters/white background) and parvocellular biased (red letters/green background). A cued T-detection task, where the stimulus onset asynchrony and the cues' features varied, was used to explore focal attention. Results: PCA patients systematically failed in reporting the global but not the local element. The parvocellular-biased condition partially improved the performance in only 1 patient. In the T-detection task, controls responded faster to targets cued by red dots and small cues as compared to no cues. Conversely, the cue's features did not affect patients' performance. Conclusions: Results only partially support the hypothesis according to which simultanagnosia is driven by an impairment in processing low-spatial frequencies. Data indicate a deficit in the flexibility of focal attention that prevents PCA patients from adapting the attentional window to the stimulus features. Simultanagnosia in PCA can be conceptualized as a complex result of a deficit involving visuoperceptual and exogenous attentional mechanisms. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Although APOE-ε4 carriers are at significantly higher risk of developing Alzheimer’s disease than non-carriers(1), controversial evidence suggests that APOE-ε4 might confer some advantages, explaining the survival of this gene (antagonistic pleiotropy)(2,3). In a population-based cohort born in one week in 1946 (assessed aged 69-71), we assessed differential effects of APOE-ε4 and β-amyloid pathology (quantified using (18)F-Florbetapir-PET) on visual working memory (object-location binding). In 398 cognitively normal participants, APOE-ε4 and β-amyloid had opposing effects on object identification, predicting better and poorer recall respectively. ε4-carriers also recalled locations more precisely, with a greater advantage at higher β-amyloid burden. These results provide evidence of superior visual working memory in ε4-carriers, showing that some benefits of this genotype are demonstrable in older age, even in the preclinical stages of Alzheimer’s disease.

Although APOE e4 carriers are at substantially higher risk of developing Alzheimer’s disease than noncarriers1, controversial evidence suggests that APOE e4 might confer some advantages, explaining the survival of this gene (antagonistic pleiotropy)2,3. In a population-based cohort born in one week in 1946 (assessed aged 69–71 years), we assessed differential effects of APOE e4 and β-amyloid pathology (quantified using 18F-Florbetapir-PET) on visual working memory (object–location binding). In 398 cognitively normal participants, APOE e4 and β-amyloid had opposing effects on object identification, predicting better and poorer recall, respectively. e4 carriers also recalled locations more precisely, with a greater advantage at higher β-amyloid burden. These results provide evidence of superior visual working memory in e4 carriers, showing that some benefits of this genotype are demonstrable in older age, even in the preclinical stages of Alzheimer’s disease. In a sample of about 400 cognitively normal older adults, APOE e4 genotype and β-amyloid pathology predicted better and poorer visual working memory, respectively, suggesting some benefits of e4 in older age, even in the preclinical stages of Alzheimer’s disease.

In the first multicentre, international longitudinal investigation of disease progression in posterior cortical atrophy, Firth et al. reveal distinct trajectories of cognitive decline and patterns of tissue loss compared to typical Alzheimer’s disease. Mapping this heterogeneity provides a basis for understanding the factors underlying variability in neurodegenerative disease expression., 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 important insights into selective vulnerability and phenotypic diversity. The present study describes the first major longitudinal investigation of posterior cortical atrophy disease progression. Three hundred and sixty-one individuals (117 posterior cortical atrophy, 106 typical Alzheimer’s disease, 138 controls) fulfilling consensus criteria for posterior cortical atrophy-pure and typical Alzheimer’s disease were recruited from three centres in the UK, Spain and USA. Participants underwent up to six annual assessments involving MRI scans and neuropsychological testing. We constructed longitudinal trajectories of regional brain volumes within posterior cortical atrophy and typical Alzheimer’s disease using differential equation models. We compared and contrasted the order in which regional brain volumes become abnormal within posterior cortical atrophy and typical Alzheimer’s disease using event-based models. We also examined trajectories of cognitive decline and the order in which different cognitive tests show abnormality using the same models. Temporally aligned trajectories for eight regions of interest revealed distinct (P < 0.002) patterns of progression in posterior cortical atrophy and typical Alzheimer’s disease. Patients with posterior cortical atrophy showed early occipital and parietal atrophy, with subsequent higher rates of temporal atrophy and ventricular expansion leading to tissue loss of comparable extent later. Hippocampal, entorhinal and frontal regions underwent a lower rate of change and never approached the extent of posterior cortical involvement. Patients with typical Alzheimer’s disease showed early hippocampal atrophy, with subsequent higher rates of temporal atrophy and ventricular expansion. Cognitive models showed tests sensitive to visuospatial dysfunction declined earlier in posterior cortical atrophy than typical Alzheimer’s disease whilst tests sensitive to working memory impairment declined earlier in typical Alzheimer’s disease than posterior cortical atrophy. These findings indicate that posterior cortical atrophy and typical Alzheimer’s disease have distinct sites of onset and different profiles of spatial and temporal progression. The ordering of disease events both motivates investigation of biological factors underpinning phenotypic heterogeneity, and informs the selection of measures for clinical trials in posterior cortical atrophy.

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 most prevalent error category in this population. Here we describe the profile of a patient with PCA, C.P., who presents an unusual prevalence of phonological, instead of purely visual, errors in his reading, in the context of an otherwise classic PCA phenotype. In keeping with the well-known PCA profile, C.P. exhibited deficits at the pre-lexical level with elements of crowding and defective early visual processing impairments but additionally showed an unusually prominent disruption of phonological processing. We also argue that our patient may have a refractory access type deficit in reading given that accuracy doubled with the introduction of a five-second response-stimulus interval. To our knowledge, no previous case of a refractory deficit affecting word reading has been reported in PCA. Our examination builds on previous knowledge about reading behaviour in PCA and describes a singular example of the rich phenotypic heterogeneity within the syndrome.

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 carriers, 17 presymptomatic carriers and 26 controls) completed the “Object-localisation” VSTM task while an eye-tracker recorded eye movements during the stimulus presentation. VSTM function and oculomotor performance were compared between groups and their association during encoding investigated. Compared to controls, symptomatic FAD carriers showed eye movement patterns suggestive of an ineffective encoding and presymptomatic FAD carriers within 6 years of their expected age at symptom onset, were more reliant on the stimuli fixation time to achieve accuracy in the localisation of the target. Consequently, for shorter fixation times on the stimuli, presymptomatic carriers were less accurate at localising the target than controls. By contrast, the only deficits detected on behavioural VSTM function was in symptomatic individuals. Our findings provide novel evidence that encoding processes may be vulnerable and weakened in presymptomatic FAD carriers, most prominently for spatial memory, suggesting a possible explanation for the subtle VSTM impairments observed in the preclinical stages of AD.

Background: Cross-sectional studies in presymptomatic familial Alzheimer’s disease (FAD), have associated binding deficits with preclinical AD. How impairments in visual-short term memory (VSTM) relate to longitudinal change and proximity to expected symptom onset (EYO) is less characterized.Methods: Thirty-two FAD mutation carriers (23 presymptomatic; 9 symptomatic) carrying a mutation in either presenilin 1 or amyloid precursor protein genes and 67 healthy controls were included in an extension VSTM cross-sectional study. Forty-eight participants (23 presymptomatic carriers, 6 symptomatic and 19 healthy controls) who had at least two annual visits (median= 3), were included in the longitudinal study. Participants completed the “What was where?” relational binding task (which measures memory for object identification, localisation and object-location binding under different conditions of memory load and delay), neuropsychology assessments and genetic testing. Results: While cross-sectionally only symptomatic carriers (N=9) showed significant impairments in VSTM performance, longitudinally, presymptomatic carriers within 8.5 years of estimated symptom onset (mean=5.8 years ±SD [1.8], N=11) showed a faster rate of decline in localisation performance in long-delay conditions (4s) compared to controls: increase/year in localisation error was 6.9% greater in the high-memory load condition (p=0.008) and 7.0% greater for the low-memory load condition (p=0.043). Change in this metric preceded presymptomatic changes in traditional measures of verbal episodic memory. Symptomatic carriers had 15% faster reduction in identification performance per year compared to controls (p=0.036) and some evidence of faster increase in localisation error (6.5% increase/year; p=0.066). The earliest significant difference in VSTM performance between FAD mutation carriers (presymptomatic and symptomatic) and controls was in localisation performance, six years prior to estimated symptom onset (p=0.024). Conclusions: This longitudinal study of FAD, suggests changes in VSTM resolution, which measure precision and thus quality of recall of the memory presentation, may be sensitive markers for tracking and predicting cognitive decline in preclinical AD.

Visual short-term memory (VSTM) deficits including VSTM binding have been associated with Alzheimer's disease (AD) from preclinical to dementia stages, cross-sectionally. Yet, longitudinal investigations are lacking. The objective of this study was to evaluate VSTM function longitudinally and in relation to expected symptom onset in a cohort of familial Alzheimer's disease. Ninety-nine individuals (23 presymptomatic; 9 symptomatic and 67 controls) were included in an extension cross-sectional study and a sub-sample of 48 (23 presymptomatic carriers, 6 symptomatic and 19 controls), attending two to five visits with a median interval of 1.3 years, included in the longitudinal study. Participants completed the “What was where?” relational binding task (which measures memory for object identification, localisation and object-location binding under different conditions of memory load and delay), neuropsychology assessments and genetic testing. Compared to controls, presymptomatic carriers within 8.5 years of estimated symptom onset showed a faster rate of decline in localisation performance in long-delay conditions (4s) and in traditional neuropsychology measures of verbal episodic memory. This study represents the first longitudinal VSTM investigation and shows that changes in memory resolution may be sensitive to tracking cognitive decline in preclinical AD at least as early as changes in the more traditional verbal episodic memory tasks., Highlights • VSTM function was investigated in presymptomatic and symptomatic FAD carriers. • PMCs showed faster decline in VSTM function (target localisation) than controls. • Target localisation accuracy decreased with proximity to expected symptom onset. • “What was where?” may be sensitive to tracking preclinical cognitive decline.

Background Understanding the earliest manifestations of Alzheimer’s disease (AD) is key to realising disease-modifying treatments. Advances in neuroimaging and fluid biomarkers have improved our ability to identify AD pathology in vivo. The critical next step is improved detection and staging of early cognitive change. We studied an asymptomatic familial Alzheimer’s disease (FAD) cohort to characterise preclinical cognitive change. Methods Data included 35 asymptomatic participants at 50% risk of carrying a pathogenic FAD mutation. Participants completed a multi-domain neuropsychology battery. After accounting for sex, age and education, we used event-based modelling to estimate the sequence of cognitive decline in presymptomatic FAD, and uncertainty in the sequence. We assigned individuals to their most likely model stage of cumulative cognitive decline, given their data. Linear regression of estimated years to symptom onset against model stage was used to estimate the timing of preclinical cognitive decline. Results Cognitive change in mutation carriers was first detected in measures of accelerated long-term forgetting, up to 10 years before estimated symptom onset. Measures of subjective cognitive decline also revealed early abnormalities. Our data-driven model demonstrated subtle cognitive impairment across multiple cognitive domains in clinically normal individuals on the AD continuum. Conclusions Data-driven modelling of neuropsychological test scores has potential to differentiate cognitive decline from cognitive stability and to estimate a fine-grained sequence of decline across cognitive domains and functions, in the preclinical phase of Alzheimer’s disease. This can improve the design of future presymptomatic trials by informing enrichment strategies and guiding the selection of outcome measures.

Blood biomarkers have great potential to advance clinical care and accelerate trials in Alzheimer’s disease (AD). Plasma phospho-tau181 (p-tau181) is a promising blood biomarker however, it is unknown if levels increase in presymptomatic AD. Therefore, we investigated the timing of p-tau181 changes using 153 blood samples from 70 individuals in a longitudinal study of familial AD (FAD). Plasma p-tau181 was measured, using an in-house single molecule array assay. We compared p-tau181 between symptomatic carriers, presymptomatic carriers, and non-carriers, adjusting for age and sex. We examined the relationship between p-tau181 and neurofilament light and estimated years to/from symptom onset (EYO), as well as years to/from actual onset in a symptomatic subgroup. In addition, we studied associations between p-tau181 and clinical severity, as well testing for differences between genetic subgroups. Twenty-four were presymptomatic carriers (mean baseline EYO −9.6 years) while 27 were non-carriers. Compared with non-carriers, plasma p-tau181 concentration was higher in both symptomatic (p

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 to reduce the reading difficulties experienced by this population (e.g., getting lost in the page and missing words when reading). Methods: Twenty subjects with PCA were included in a cross-over design home-based study aimed at determining whether ReadClear could 1) enhance the subjective reading experience (reading pleasantness) and 2) improve reading accuracy (reducing the number of reading errors) compared with a sham condition (a standard e-reader). Results: Reading using ReadClear provided a better subjective reading experience than sham (p=0.018, d=0.5) and significantly reduced the percentage of reading errors (p

Aim To measure changes in visuo-perceptual processing in patients with Parkinson9s disease without dementia. Methods Images of cats and dogs that had been skewed by varying amounts were shown to patients with idiopathic Parkinson9s disease (defined by QSBB criteria) (n=16) and healthy controls (n=11). Mean disease duration was 4 years (Standard deviation 3 years). Average L-DOPA equivalent dose was 554 mg (SD 487 mg). On each trial, participants were asked to identify the presented animal to generate psychophysical curves of skew against correctness and determine the threshold for identifying the correct animal. Visual acuity, UPDRS-scores and neuropsychology performance was measured for each participant. Results Patients with Parkinson9s disease, but without dementia, showed impaired ability to identify images that had been skewed, compared with healthy controls. The threshold for detection in patients was 61.2 degrees (SD 7.1 degrees), compared with 67.9 degrees (SD 2.1 degrees) in healthy participants, W=143, p=0.0056. The groups did not differ in visual acuity or neuropsychological performance. Conclusions We show subtle but definite impairment of complex visual processing in the initial phases of Parkinson9s disease in patients without overt cognitive impairment. This work has important implications for understanding the diagnosis, biology and progression of Parkinson9s disease.