Data-driven modelling of neurodegenerative disease progression: thinking outside the black box.

Data-driven disease progression models are an emerging set of computational tools that reconstruct disease timelines for long-term chronic diseases, providing unique insights into disease processes and their underlying mechanisms. Such methods combine a priori human knowledge and assumptions with large-scale data processing and parameter estimation to infer long-term disease trajectories from short-term data. In contrast to 'black box' machine learning tools, data-driven disease progression models typically require fewer data and are inherently interpretable, thereby aiding disease understanding in addition to enabling classification, prediction and stratification. In this Review, we place the current landscape of data-driven disease progression models in a general framework and discuss their enhanced utility for constructing a disease timeline compared with wider machine learning tools that construct static disease profiles. We review the insights they have enabled across multiple neurodegenerative diseases, notably Alzheimer disease, for applications such as determining temporal trajectories of disease biomarkers, testing hypotheses about disease mechanisms and uncovering disease subtypes. We outline key areas for technological development and translation to a broader range of neuroscience and non-neuroscience applications. Finally, we discuss potential pathways and barriers to integrating disease progression models into clinical practice and trial settings.

Longitudinal inference of multiscale markers in psychosis: from hippocampal centrality to functional outcome.

Multiscale neuroscience conceptualizes mental illness as arising from aberrant interactions across and within multiple biopsychosocial scales. We leverage this framework to propose a multiscale disease progression model of psychosis, in which hippocampal-cortical dysconnectivity precedes impairments in episodic memory and social cognition, which lead to more severe negative symptoms and lower functional outcome. As psychosis represents a heterogeneous collection of biological and behavioral alterations that evolve over time, we further predict this disease progression for a subtype of the patient sample, with other patients showing normal-range performance on all variables. We sampled data from two cross-sectional datasets of first- and multi-episode psychosis, resulting in a sample of 163 patients and 119 non-clinical controls. To address our proposed disease progression model and evaluate potential heterogeneity, we applied a machine-learning algorithm, SuStaIn, to the patient data. SuStaIn uniquely integrates clustering and disease progression modeling and identified three patient subtypes. Subtype 0 showed normal-range performance on all variables. In comparison, Subtype 1 showed lower episodic memory, social cognition, functional outcome, and higher negative symptoms, while Subtype 2 showed lower hippocampal-cortical connectivity and episodic memory. Subtype 1 deteriorated from episodic memory to social cognition, negative symptoms, functional outcome to bilateral hippocampal-cortical dysconnectivity, while Subtype 2 deteriorated from bilateral hippocampal-cortical dysconnectivity to episodic memory and social cognition, functional outcome to negative symptoms. This first application of SuStaIn in a multiscale psychiatric model provides distinct disease trajectories of hippocampal-cortical connectivity, which might underlie the heterogeneous behavioral manifestations of psychosis.

Towards cascading genetic risk in Alzheimer's disease.

Alzheimer's disease typically progresses in stages, which have been defined by the presence of disease-specific biomarkers: Amyloid (A), Tau (T) and neurodegeneration (N). This progression of biomarkers has been condensed into the ATN framework, where each of the biomarkers can be either positive (+) or negative (-). Over the past decades genome wide association studies have implicated about 90 different loci involved with the development of late onset Alzheimer's disease. Here we investigate whether genetic risk for Alzheimer's disease contributes equally to the progression in different disease stages or whether it exhibits a stage-dependent effect. Amyloid (A) and tau (T) status was defined using a combination of available PET and CSF biomarkers in the Alzheimer's Disease Neuroimaging Initiative cohort. In 312 participants with biomarker-confirmed A-T- status, we employed Cox proportional hazards models to estimate the contribution of APOE and polygenic risk scores (beyond APOE) to convert to A+T- status (65 conversions). Furthermore, we repeated the analysis in 290 participants with A+T- status and investigated the genetic contribution to conversion to A+T+ (45 conversions). Both survival analyses were adjusted for age, sex, and years of education. For progression from A-T- to A+T-, APOE-e4 burden showed significant effect (HR=2.88; 95% CI: 1.70-4.89; P<0.001), while polygenic risk did not (HR=1.09; 95% CI: 0.84-1.42; P=0.53). Conversely, for the transition from A+T- to A+T+, the APOE-e4 burden contribution was reduced (HR=1.62 95% CI: 1.05-2.51; P=0.031), while the polygenic risk showed an increased contribution (HR=1.73; 95% CI:1.27-2.36; P<0.001). The marginal APOE effect was driven by e4 homozygotes (HR=2.58; 95% CI: 1.05-6.35; P=0.039) as opposed to e4 heterozygotes (HR=1.74; 95% CI: 0.87-3.49; P=0.12). The genetic risk for late-onset Alzheimer's disease unfolds in a disease stage-dependent fashion. A better understanding of the interplay between disease stage and genetic risk can lead to a more mechanistic understanding of transition between ATN stages, a better understanding of the molecular processes leading to Alzheimer's disease as well as opening therapeutic windows for targeted interventions.

Mortality surrogates in combined pulmonary fibrosis and emphysema.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) with coexistent emphysema, termed combined pulmonary fibrosis and emphysema (CPFE) may associate with reduced forced vital capacity (FVC) declines compared to non-CPFE IPF patients. We examined associations between mortality and functional measures of disease progression in two IPF cohorts. METHODS: Visual emphysema presence (>0% emphysema) scored on computed tomography identified CPFE patients (CPFE/non-CPFE: derivation cohort n=317/n=183, replication cohort n=358/n=152), who were subgrouped using 10% or 15% visual emphysema thresholds, and an unsupervised machine-learning model considering emphysema and interstitial lung disease extents. Baseline characteristics, 1-year relative FVC and diffusing capacity of the lung for carbon monoxide (D LCO) decline (linear mixed-effects models), and their associations with mortality (multivariable Cox regression models) were compared across non-CPFE and CPFE subgroups. RESULTS: In both IPF cohorts, CPFE patients with ≥10% emphysema had a greater smoking history and lower baseline D LCO compared to CPFE patients with <10% emphysema. Using multivariable Cox regression analyses in patients with ≥10% emphysema, 1-year D LCO decline showed stronger mortality associations than 1-year FVC decline. Results were maintained in patients suitable for therapeutic IPF trials and in subjects subgrouped by ≥15% emphysema and using unsupervised machine learning. Importantly, the unsupervised machine-learning approach identified CPFE patients in whom FVC decline did not associate strongly with mortality. In non-CPFE IPF patients, 1-year FVC declines ≥5% and ≥10% showed strong mortality associations. CONCLUSION: When assessing disease progression in IPF, D LCO decline should be considered in patients with ≥10% emphysema and a ≥5% 1-year relative FVC decline threshold considered in non-CPFE IPF patients.

A data-driven study of Alzheimer's disease related amyloid and tau pathology progression.

Amyloid-ß is thought to facilitate the spread of tau throughout the neocortex in Alzheimer's disease, though how this occurs is not well understood. This is because of the spatial discordance between amyloid-ß, which accumulates in the neocortex, and tau, which accumulates in the medial temporal lobe during ageing. There is evidence that in some cases amyloid-ß-independent tau spreads beyond the medial temporal lobe where it may interact with neocortical amyloid-ß. This suggests that there may be multiple distinct spatiotemporal subtypes of Alzheimer's-related protein aggregation, with potentially different demographic and genetic risk profiles. We investigated this hypothesis, applying data-driven disease progression subtyping models to post-mortem neuropathology and in vivo PET-based measures from two large observational studies: the Alzheimer's Disease Neuroimaging Initiative (ADNI) and the Religious Orders Study and Rush Memory and Aging Project (ROSMAP). We consistently identified 'amyloid-first' and 'tau-first' subtypes using cross-sectional information from both studies. In the amyloid-first subtype, extensive neocortical amyloid-ß precedes the spread of tau beyond the medial temporal lobe, while in the tau-first subtype, mild tau accumulates in medial temporal and neocortical areas prior to interacting with amyloid-ß. As expected, we found a higher prevalence of the amyloid-first subtype among apolipoprotein E (APOE) ε4 allele carriers while the tau-first subtype was more common among APOE ε4 non-carriers. Within tau-first APOE ε4 carriers, we found an increased rate of amyloid-ß accumulation (via longitudinal amyloid PET), suggesting that this rare group may belong within the Alzheimer's disease continuum. We also found that tau-first APOE ε4 carriers had several fewer years of education than other groups, suggesting a role for modifiable risk factors in facilitating amyloid-ß-independent tau. Tau-first APOE ε4 non-carriers, in contrast, recapitulated many of the features of primary age-related tauopathy. The rate of longitudinal amyloid-ß and tau accumulation (both measured via PET) within this group did not differ from normal ageing, supporting the distinction of primary age-related tauopathy from Alzheimer's disease. We also found reduced longitudinal subtype consistency within tau-first APOE ε4 non-carriers, suggesting additional heterogeneity within this group. Our findings support the idea that amyloid-ß and tau may begin as independent processes in spatially disconnected regions, with widespread neocortical tau resulting from the local interaction of amyloid-ß and tau. The site of this interaction may be subtype-dependent: medial temporal lobe in amyloid-first, neocortex in tau-first. These insights into the dynamics of amyloid-ß and tau may inform research and clinical trials that target these pathologies.

Data-driven neuropathological staging and subtyping of TDP-43 proteinopathies.

TAR DNA-binding protein-43 (TDP-43) accumulation is the primary pathology underlying several neurodegenerative diseases. Charting the progression and heterogeneity of TDP-43 accumulation is necessary to better characterize TDP-43 proteinopathies, but current TDP-43 staging systems are heuristic and assume each syndrome is homogeneous. Here, we use data-driven disease progression modelling to derive a fine-grained empirical staging system for the classification and differentiation of frontotemporal lobar degeneration due to TDP-43 (FTLD-TDP, n = 126), amyotrophic lateral sclerosis (ALS, n = 141) and limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) with and without Alzheimer's disease (n = 304). The data-driven staging of ALS and FTLD-TDP complement and extend previously described human-defined staging schema for ALS and behavioural variant frontotemporal dementia. In LATE-NC individuals, progression along data-driven stages was positively associated with age, but negatively associated with age in individuals with FTLD-TDP. Using only regional TDP-43 severity, our data driven model distinguished individuals diagnosed with ALS, FTLD-TDP or LATE-NC with a cross-validated accuracy of 85.9%, with misclassifications associated with mixed pathological diagnosis, age and genetic mutations. Adding age and SuStaIn stage to this model increased accuracy to 92.3%. Our model differentiates LATE-NC from FTLD-TDP, though some overlap was observed between late-stage LATE-NC and early-stage FTLD-TDP. We further tested for the presence of subtypes with distinct regional TDP-43 progression patterns within each diagnostic group, identifying two distinct cortical-predominant and brainstem-predominant subtypes within FTLD-TDP and a further two subcortical-predominant and corticolimbic-predominant subtypes within ALS. The FTLD-TDP subtypes exhibited differing proportions of TDP-43 type, while there was a trend for age differing between ALS subtypes. Interestingly, a negative relationship between age and SuStaIn stage was seen in the brainstem/subcortical-predominant subtype of each proteinopathy. No subtypes were observed for the LATE-NC group, despite aggregating individuals with and without Alzheimer's disease and a larger sample size for this group. Overall, we provide an empirical pathological TDP-43 staging system for ALS, FTLD-TDP and LATE-NC, which yielded accurate classification. We further demonstrate that there is substantial heterogeneity amongst ALS and FTLD-TDP progression patterns that warrants further investigation in larger cross-cohort studies.

Identification of different MRI atrophy progression trajectories in epilepsy by subtype and stage inference.

Artificial intelligence (AI)-based tools are widely employed, but their use for diagnosis and prognosis of neurological disorders is still evolving. Here we analyse a cross-sectional multicentre structural MRI dataset of 696 people with epilepsy and 118 control subjects. We use an innovative machine-learning algorithm, Subtype and Stage Inference, to develop a novel data-driven disease taxonomy, whereby epilepsy subtypes correspond to distinct patterns of spatiotemporal progression of brain atrophy.In a discovery cohort of 814 individuals, we identify two subtypes common to focal and idiopathic generalized epilepsies, characterized by progression of grey matter atrophy driven by the cortex or the basal ganglia. A third subtype, only detected in focal epilepsies, was characterized by hippocampal atrophy. We corroborate external validity via an independent cohort of 254 people and confirm that the basal ganglia subtype is associated with the most severe epilepsy.Our findings suggest fundamental processes underlying the progression of epilepsy-related brain atrophy. We deliver a novel MRI- and AI-guided epilepsy taxonomy, which could be used for individualized prognostics and targeted therapeutics.

Co-design of a paediatric post-trauma electronic psychosocial screen.

PURPOSE: To optimise care pathways and provide greater transparency of the psychosocial needs of injured children after hospital discharge by extending post-discharge psychosocial screening to children admitted with traumatic injury for ≥24 h. DESIGN AND METHODS: This mixed-methods study used a co-design approach informed by the Experience-Based Co-design (EBCD) framework. Interviews with carers were used to evaluate experiences and generate views on psychosocial support interventions. Online surveys by international child psychologists' indicated preferences for a psychosocial screening tool, and clinician-stakeholder consensus meetings facilitated the development of an electronic post-injury psychosocial screening tool. RESULTS: Carers found the initial year of follow-up from trauma family support services helpful, appreciating the hospital connection. Flexible follow-up timings and additional resources were mentioned, and most carers were interested in participating in an electronic screening activity to predict their child's coping after injury. Child trauma experts recommended including several screening tools, and the multidisciplinary paediatric trauma service and study investigators collaborated over a year to workshop and reach a consensus on the screening tool and follow-up process. CONCLUSION: The multidisciplinary team co-designed an electronic psychosocial screening and follow-up process for families with children with traumatic injuries. This tool improves the visibility of injured children's psychosocial needs post-injury and potentially aids clinical targeted resource allocation for trauma family support services. PRACTICE IMPLICATIONS: The study emphasises the significance of specialised psychosocial screening tools in paediatric nursing, especially in trauma care, for understanding patients' psychosocial needs, tailoring follow-up plans, and promoting a patient-centred approach.

Barriers and co-designed strategies for the implementation of negative pressure wound therapy in acute pediatric burn care in Australia: A mixed method study.

PURPOSE: Pediatric burn injuries are a global clinical issue causing significant morbidity. Early adjunctive negative pressure wound therapy improves re-epithelialization rates in children with burns, yet adoption in acute burn care is inconsistent. This investigation aimed to determine barriers to the implementation of adjunctive negative pressure wound therapy for the acute management of pediatric burns and co-design targeted implementation strategies. METHODS: A sequential mixed methods design was used explore barriers to adjunctive negative pressure wound therapy implementation in acute pediatric burn care. An online questionnaire was disseminated to healthcare professionals within four major Australian pediatric hospitals, each with a dedicated burns service. Barriers were coded according to the Consolidated Framework for Implementation Research (CFIR). Semi-structured interviews with senior clinicians tailored implementation strategies to local contexts. A stakeholder consensus meeting consolidated implementation strategies and local processes. RESULTS: Sixty-three healthcare professionals participated in the questionnaire, and semi-structured interviews involved nine senior burn clinicians. We identified eight implementation barriers across all five CFIR domains then co-designed targeted strategies to address identified barriers. Barriers included lack of available resources, limited access to knowledge and information, individual stage of change, patient needs and resources, limited knowledge and beliefs about the intervention, lack of external policies, intervention complexity, and poor implementation planning. CONCLUSION: Multiple contextual factors affect negative pressure wound therapy uptake in acute pediatric burn settings. Results will inform a multi-state stepped-wedge cluster randomized controlled trial. Additional resources, education, training, updated policies, and guidelines are required for successful implementation. It is anticipated that adjunctive negative pressure wound therapy, in conjunction with tailored implementation strategies, will enhance adoption and sustainability. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry: ACTRN12622000166774. Registered 1 February 2022.

Transferability of Alzheimer's disease progression subtypes to an independent population cohort.

In the past, methods to subtype or biotype patients using brain imaging data have been developed. However, it is unclear whether and how these trained machine learning models can be successfully applied to population cohorts to study the genetic and lifestyle factors underpinning these subtypes. This work, using the Subtype and Stage Inference (SuStaIn) algorithm, examines the generalisability of data-driven Alzheimer's disease (AD) progression models. We first compared SuStaIn models trained separately on Alzheimer's disease neuroimaging initiative (ADNI) data and an AD-at-risk population constructed from the UK Biobank dataset. We further applied data harmonization techniques to remove cohort effects. Next, we built SuStaIn models on the harmonized datasets, which were then used to subtype and stage subjects in the other harmonized dataset. The first key finding is that three consistent atrophy subtypes were found in both datasets, which match the previously identified subtype progression patterns in AD: 'typical', 'cortical' and 'subcortical'. Next, the subtype agreement was further supported by high consistency in individuals' subtypes and stage assignment based on the different models: more than 92% of the subjects, with reliable subtype assignment in both ADNI and UK Biobank dataset, were assigned to an identical subtype under the model built on the different datasets. The successful transferability of AD atrophy progression subtypes across cohorts capturing different phases of disease development enabled further investigations of associations between AD atrophy subtypes and risk factors. Our study showed that (1) the average age is highest in the typical subtype and lowest in the subcortical subtype; (2) the typical subtype is associated with statistically more-AD-like cerebrospinal fluid biomarkers values in comparison to the other two subtypes; and (3) in comparison to the subcortical subtype, the cortical subtype subjects are more likely to associate with prescription of cholesterol and high blood pressure medications. In summary, we presented cross-cohort consistent recovery of AD atrophy subtypes, showing how the same subtypes arise even in cohorts capturing substantially different disease phases. Our study opened opportunities for future detailed investigations of atrophy subtypes with a broad range of early risk factors, which will potentially lead to a better understanding of the disease aetiology and the role of lifestyle and behaviour on AD.

Sequence of clinical and neurodegeneration events in Parkinson's disease progression.

Dementia is one of the most debilitating aspects of Parkinson's disease. There are no validated biomarkers that can track Parkinson's disease progression, nor accurately identify patients who will develop dementia and when. Understanding the sequence of observable changes in Parkinson's disease in people at elevated risk for developing dementia could provide an integrated biomarker for identifying and managing individuals who will develop Parkinson's dementia. We aimed to estimate the sequence of clinical and neurodegeneration events, and variability in this sequence, using data-driven statistical modelling in two separate Parkinson's cohorts, focusing on patients at elevated risk for dementia due to their age at symptom onset. We updated a novel version of an event-based model that has only recently been extended to cope naturally with clinical data, enabling its application in Parkinson's disease for the first time. The observational cohorts included healthy control subjects and patients with Parkinson's disease, of whom those diagnosed at age 65 or older were classified as having high risk of dementia. The model estimates that Parkinson's progression in patients at elevated risk for dementia starts with classic prodromal features of Parkinson's disease (olfaction, sleep), followed by early deficits in visual cognition and increased brain iron content, followed later by a less certain ordering of neurodegeneration in the substantia nigra and cortex, neuropsychological cognitive deficits, retinal thinning in dopamine layers, and further deficits in visual cognition. Importantly, we also characterize variation in the sequence. We found consistent, cross-validated results within cohorts, and agreement between cohorts on the subset of features available in both cohorts. Our sequencing results add powerful support to the increasing body of evidence suggesting that visual processing specifically is affected early in patients with Parkinson's disease at elevated risk of dementia. This opens a route to earlier and more precise detection, as well as a more detailed understanding of the pathological mechanisms underpinning Parkinson's dementia.

Self-management by older people living with cancer and multi-morbidity: a qualitative study.

PURPOSE: Over half of individuals diagnosed with cancer are aged over 70 years, and more than 75% of those with cancer report at least one other medical condition. Having multiple conditions alongside cancer in old age may lower functional status, greater likelihood of treatment complications and less favourable prognoses. This qualitative study explored how older people with long-term chronic conditions manage their health and meet their health-related goals after they have completed treatment for cancer. METHODS: One-to-one face-to-face qualitative interviews were conducted with 8 older people and 2 informal caregivers based in the UK. Older adults were eligible to participate if they were over 70 and had completed primary cancer treatment with curative intent and had at least one other chronic health condition. A semi-structured interview schedule developed a priori based on Shippee's cumulative complexity model was used. We aimed to explore experiences that could influence self-management, utilisation of healthcare services and health outcomes. A framework analysis was used to describe and interpret the data. RESULTS: Four overarching themes were identified in the analysis. These themes related to factors that influenced the everyday health-related workload and capacity of the participants. These factors included their health, resources, and opportunities, as well their motivation and sense of perceived control over their lives. CONCLUSIONS: Fragmented healthcare systems and relationships with healthcare professionals also influenced the participants' self-management of their health. Our findings highlight the interaction between an individuals' needs, capacity, treatment burden, and the services and resources available to them. These findings support calls to promote person-centred care to better support older adults to manage their health.

Association between Quality of Interactions Schedule ratings and care experiences of people with a dementia in general hospital settings: a validation study.

INTRODUCTION: Establishing methods to evaluate interactions between hospital staff and patients with a dementia is vital to inform care delivery. This study aimed to assess the validity of Quality of Interactions Schedule (QuIS) ratings in relation to the care experiences of people with a dementia in a general hospital setting. METHODS: Four hundred and ninety face-to-face interactions between staff and patients with a dementia (n = 107) on six medicine for older people wards in a UK National Health Service hospital were observed and rated using QuIS and the Psychological Well-Being in Cognitively Impaired Persons (PWB-CIP) tool. We also invited patient ratings for longer interactions (n = 217). Analyses explored associations between QuIS ratings, PWB-CIP ratings and patient ratings. RESULTS: When QuIS was rated negative, the mean researcher-rated patient psychological well-being was lower (PWB = 7.9 out of maximum score of 10) than when QuIS was non-negative (PWB = 8.8, p = 0.036). Negative QuIS ratings were associated with negative ratings on seven out of ten individual PWB-CIP items. When QuIS was rated negative, the associated patient rating was 4% less likely to be 'happy'. The patient was also 4% more likely to rate the interaction as 'kind'. Patients struggled to participate in care ratings. CONCLUSIONS: Some patients found responding to researcher questions difficult or not relevant, reflecting the need for development of more suitable methods in this field. Our findings of an association between lower quality QuIS-rated interactions and lower psychological well-being lend support to the use of QuIS with patient populations that include people with a dementia.

Topical Review: Medical Trauma During Early Childhood.

OBJECTIVE: Early childhood is a high-risk period for exposure to traumatic medical events due to injury/illness. It is also one of the most important and vulnerable periods due to rapid development in neurobiological systems, attachment relationships, cognitive and linguistic capacities, and emotion regulation. The aim of this topical review is to evaluate empirical literature on the psychological impact of medical trauma during early childhood (0-6 years) to inform models of clinical care for assessing, preventing, and treating traumatic stress following injury/illness. METHODS: Topical review of empirical and theoretical literature on pediatric medical traumatic stress (PMTS) during early childhood. RESULTS: There are important developmental factors that influence how infants and young children perceive and respond to medical events. The emerging literature indicates that up to 30% of young children experience PMTS within the first month of an acute illness/injury and between 3% and 10% develop posttraumatic stress disorder. However, significant knowledge gaps remain in our understanding of psychological outcomes for infants and young children, identification of risk-factors and availability of evidence-based interventions for medical trauma following illness. CONCLUSIONS: This topical review on medical trauma during early childhood provides: (a) definitions of key medical trauma terminology, (b) discussion of important developmental considerations, (c) summary of the empirical literature on psychological outcomes, risk factors, and interventions, (d) introduction to a stepped-model-of-care framework to guide clinical practice, and (e) summary of limitations and directions for future research.

Disease Progression Modeling in Chronic Obstructive Pulmonary Disease.

Rationale: The decades-long progression of chronic obstructive pulmonary disease (COPD) renders identifying different trajectories of disease progression challenging.Objectives: To identify subtypes of patients with COPD with distinct longitudinal progression patterns using a novel machine-learning tool called "Subtype and Stage Inference" (SuStaIn) and to evaluate the utility of SuStaIn for patient stratification in COPD.Methods: We applied SuStaIn to cross-sectional computed tomography imaging markers in 3,698 Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1-4 patients and 3,479 controls from the COPDGene (COPD Genetic Epidemiology) study to identify subtypes of patients with COPD. We confirmed the identified subtypes and progression patterns using ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) data. We assessed the utility of SuStaIn for patient stratification by comparing SuStaIn subtypes and stages at baseline with longitudinal follow-up data.Measurements and Main Results: We identified two trajectories of disease progression in COPD: a "Tissue→Airway" subtype (n = 2,354, 70.4%), in which small airway dysfunction and emphysema precede large airway wall abnormalities, and an "Airway→Tissue" subtype (n = 988, 29.6%), in which large airway wall abnormalities precede emphysema and small airway dysfunction. Subtypes were reproducible in ECLIPSE. Baseline stage in both subtypes correlated with future FEV1/FVC decline (r = -0.16 [P < 0.001] in the Tissue→Airway group; r = -0.14 [P = 0.011] in the Airway→Tissue group). SuStaIn placed 30% of smokers with normal lung function at elevated stages, suggesting imaging changes consistent with early COPD. Individuals with early changes were 2.5 times more likely to meet COPD diagnostic criteria at follow-up.Conclusions: We demonstrate two distinct patterns of disease progression in COPD using SuStaIn, likely representing different endotypes. One third of healthy smokers have detectable imaging changes, suggesting a new biomarker of "early COPD."

Accuracy of delirium assessments in critically ill children: A prospective, observational study during routine care.

OBJECTIVES: The objectives of this study was to explore the accuracy of the Cornell Assessment for Pediatric Delirium (CAP-D), Pediatric Confusion Assessment Method for the Intensive Care Unit (pCAM-ICU), and Preschool Confusion Assessment Method for the Intensive Care Unit (psCAM-ICU) when implemented in routine care as delirium screening tools, and to assess patient characteristics and clinical variables that may affect their validity. DESIGN: This is a prospective observational study. SETTING: The study was conducted in a 36-bed, mixed paediatric intensive care unit (PICU) at an Australian tertiary hospital. PATIENTS: The study included critically ill children developmentally aged 6 months to 17 years, with a PICU length of stay >18 h. INTERVENTIONS: No interventions were provided in the study. MEASUREMENTS AND MAIN RESULTS: Patients were screened for delirium by their bedside nurse (CAP-D and pCAM-ICU/psCAM-ICU) once daily, for up to 5 d. Delirium status identified using screening instruments was compared with delirium diagnosis using the diagnostic criteria for delirium (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition). In this sample, the CAP-D retained its high sensitivity (91.3%) and good specificity (75.2%), whereas the psCAM-ICU and pCAM-ICU had moderate sensitivity (58.8% and 75.0%, respectively) and excellent specificity (89.8% and 84.9%, respectively). There was moderate agreement between the CAP-D and the psCAM-ICU (κ = 0.52, p < .001) and good agreement between the CAP-D and the pCAM-ICU (κ = 0.80, p < .01). CONCLUSIONS: Although the CAP-D, psCAM-ICU, and pCAM-ICU all appear promising in their validation studies, when implemented in routine care, their performance can be variable. The CAP-D performed well in routine clinical practice, but follow-up diagnosis is required to confirm delirium. The psCAM-ICU and pCAM-ICU both provide valuable, objective assessments of delirium in critically ill children; however, further evaluation of their implementation in routine clinical practice is needed.

Prion propagation estimated from brain diffusion MRI is subtype dependent in sporadic Creutzfeldt-Jakob disease.

Sporadic Creutzfeldt-Jakob disease (sCJD) is a transmissible brain proteinopathy. Five main clinicopathological subtypes (sCJD-MM(V)1, -MM(V)2C, -MV2K, -VV1, and -VV2) are currently distinguished. Histopathological evidence suggests that the localisation of prion aggregates and spongiform lesions varies among subtypes. Establishing whether there is an initial site with detectable imaging abnormalities (epicentre) and an order of lesion propagation would be informative for disease early diagnosis, patient staging, management and recruitment in clinical trials. Diffusion magnetic resonance imaging (MRI) is the most-used and most-sensitive test to detect spongiform degeneration. This study was designed to identify, in vivo and for the first time, subtype-dependent epicentre and lesion propagation in the brain using diffusion-weighted images (DWI), in the largest known cross-sectional dataset of autopsy-proven subjects with sCJD. We estimate lesion propagation by cross-sectional DWI using event-based modelling, a well-established data-driven technique. DWI abnormalities of 594 autopsy-diagnosed subjects (448 patients with sCJD) were scored in 12 brain regions by 1 neuroradiologist blind to the diagnosis. We used the event-based model to reconstruct sequential orderings of lesion propagation in each of five pure subtypes. Follow-up data from 151 patients validated the estimated sequences. Results showed that epicentre and ordering of lesion propagation are subtype specific. The two most common subtypes (-MM1 and -VV2) showed opposite ordering of DWI abnormality appearance: from the neocortex to subcortical regions, and vice versa, respectively. The precuneus was the most likely epicentre also in -MM2 and -VV1 although at variance with -MM1, abnormal signal was also detected early in cingulate and insular cortices. The caudal-rostral sequence of lesion propagation that characterises -VV2 was replicated in -MV2K. Combined, these data-driven models provide unprecedented dynamic insights into subtype-specific epicentre at onset and propagation of the pathologic process, which may also enhance early diagnosis and enable disease staging in sCJD.

Preventive intervention for trauma reactions in young injured children: results of a multi-site randomised controlled trial.

BACKGROUND: Young children are at particular risk for injury. Ten per cent to twenty-five per cent develop posttraumatic stress disorder (PTSD). However, no empirically supported preventive interventions exist. Therefore, this study evaluated the efficacy of a standardised targeted preventive intervention for PTSD in young injured children. METHODS: Injured children (1-6 years) were enrolled in a multi-site parallel-group superiority prospective randomised controlled trial (RCT) in Australia and Switzerland. Screening for PTSD risk occurred 6-8 days postaccident. Parents of children who screened 'high-risk' were randomised to a 2-session CBT-based intervention or treatment-as-usual (TAU). Primary outcomes were PTSD symptom (PTSS) severity, and secondary outcomes were PTSD diagnosis, functional impairment and behavioural difficulties at 3 and 6 months postinjury using blinded assessments. Trials were registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614000325606) and ClinicalTrials.gov (NCT02088814). Trial status is complete. RESULTS: One hundred and thirty-three children screened 'high-risk' were assigned to intervention (n = 62) or TAU (n = 71). Multilevel intention-to-treat analyses revealed a significant intervention effect on PTSS severity over time (b = 60.06, 95% CI: 21.30-98.56). At 3 months, intervention children (M = 11.02, SD = 10.42, range 0-47) showed an accelerated reduction in PTSS severity scores compared to control children (M = 17.30, SD = 13.94, range 0-52; mean difference -6.97, 95% CI: -14.02 to 0.08, p adj. = .055, d = 0.51). On secondary outcomes, multilevel analyses revealed significant treatment effects for PTSD diagnosis, functional impairment and behavioural difficulties. CONCLUSIONS: This multi-site RCT provides promising preliminary evidence for the efficacy of a targeted preventive intervention for accelerating recovery from PTSS in young injured children. This has important clinical implications for the psychological support provided to young children and parents during the acute period following a single-event trauma.

Longitudinal neuroanatomical and cognitive progression of posterior cortical atrophy.

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.

Sequences of cognitive decline in typical Alzheimer's disease and posterior cortical atrophy estimated using a novel event-based model of disease progression.

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 Research Centre. Our neuropsychological battery assessed memory, vision, arithmetic, and general cognition. We adapted the event-based model to handle highly non-Gaussian data such as cognitive test scores where ceiling/floor effects are common. RESULTS: Experiments revealed differences and similarities in the fine-grained ordering of cognitive decline in PCA (vision first) and tAD (memory first). Simulation experiments reveal that our new model equals or exceeds performance of the classic event-based model, especially for highly non-Gaussian data. DISCUSSION: Our model recovered realistic, phenotypical progression signatures that may be applied in dementia clinical trials for enrichment, and as a data-driven composite cognitive end-point.