Exploring semantic verbal fluency patterns and their relationship to age and Alzheimer's disease in adults with Down syndrome.

Introduction: Adults with Down syndrome (DS) are at ultra-high risk of developing Alzheimer's disease (AD), characterized by poor episodic memory and semantic fluency in the preclinical phase in the general population. We explored semantic fluency performance in DS and its relationship to age, AD, and blood biomarkers.

Methods: A total of 302 adults with DS at baseline and 87 at follow-up from the London Down Syndrome Consortium cohort completed neuropsychological assessments.

Comparison of resting-state EEG between adults with Down syndrome and typically developing controls.

Background: Down syndrome (DS) is the most common genetic cause of intellectual disability (ID) worldwide. Understanding electrophysiological characteristics associated with DS provides potential mechanistic insights into ID, helping inform biomarkers and targets for intervention. Currently, electrophysiological characteristics associated with DS remain unclear due to methodological differences between studies and inadequate controls for cognitive decline as a potential cofounder.

Optimal age and outcome measures for Alzheimer's disease prevention trials in people with Down syndrome.

Introduction: People with Down syndrome (DS) typically develop Alzheimer's disease (AD) neuropathology before age 40, but a lack of outcome measures and longitudinal data have impeded their inclusion in randomized controlled trials (RCTs).

Methods: Cohort study. Event-based and dose-response E models were fitted to longitudinal cognitive data, to stage AD and determine the earliest ages of decline.

Differential Associations of Apolipoprotein E ε4 Genotype With Attentional Abilities Across the Life Span of Individuals With Down Syndrome.

Importance: Risk of Alzheimer disease (AD) is particularly high for individuals with Down syndrome (DS). The ε4 allele of the apolipoprotein E gene (APOE ε4) is associated with an additional risk for AD. In typical development, there is evidence that the APOE ε4 genotype is associated with an early cognitive advantage.

Health comorbidities and cognitive abilities across the lifespan in Down syndrome.

Background: Down syndrome (DS) is associated with variable intellectual disability and multiple health and psychiatric comorbidities. The impact of such comorbidities on cognitive outcomes is unknown. We aimed to describe patterns of physical health and psychiatric comorbidity prevalence, and receptive language ability, in DS across the lifespan, and determine relationships with cognitive outcomes.

Assessing general cognitive and adaptive abilities in adults with Down syndrome: a systematic review.

Background: Measures of general cognitive and adaptive ability in adults with Down syndrome (DS) used by previous studies vary substantially. This review summarises the different ability measures used previously, focusing on tests of intelligence quotient (IQ) and adaptive behaviour (AB), and where possible examines floor effects and differences between DS subpopulations. We aimed to use information regarding existing measures to provide recommendations for individual researchers and the DS research community.

Validating the Cognitive Scale for Down Syndrome (CS-DS) to Detect Longitudinal Cognitive Decline in Adults With Down Syndrome.

Down syndrome (DS) is associated with intellectual disability and an ultra-high risk of developing dementia. Informant ratings are invaluable to assess abilities and related changes in adults with DS, particularly for those with more severe intellectual disabilities and/or cognitive decline. We previously developed the informant rated Cognitive Scale for Down Syndrome (CS-DS) to measure everyday cognitive abilities across memory, executive function, and language domains in adults with DS, finding CS-DS scores are a valid measure of general abilities, and are significantly lower for those with noticeable cognitive decline compared to those without decline.

Plasma biomarkers for amyloid, tau, and cytokines in Down syndrome and sporadic Alzheimer's disease.

Background: Down syndrome (DS), caused by chromosome 21 trisomy, is associated with an ultra-high risk of dementia due to Alzheimer's disease (AD), driven by amyloid precursor protein (APP) gene triplication. Understanding relevant molecular differences between those with DS, those with sporadic AD (sAD) without DS, and controls will aid in understanding AD development in DS. We explored group differences in plasma concentrations of amyloid-β peptides and tau (as their accumulation is a characteristic feature of AD) and cytokines (as the inflammatory response has been implicated in AD development, and immune dysfunction is common in DS).

Dynamic Causal Modeling of the Relationship between Cognition and Theta-alpha Oscillations in Adults with Down Syndrome.

Individuals with Down syndrome (DS) show high inter-subject variability in cognitive ability and have an ultra-high risk of developing dementia (90% lifetime prevalence). Elucidating factors underlying variability in cognitive function can inform us about intellectual disability (ID) and may improve our understanding of factors associated with later cognitive decline. Increased neuronal inhibition has been posited to contribute to ID in DS.

Comparison of Receptive Verbal Abilities Assessed Using the KBIT-2 and BPVS3 in Adults With Down Syndrome.

Down syndrome (DS) is the most common genetic cause of intellectual disability. There is, however, considerable variation in cognitive abilities between those with DS, with some individuals scoring at floor on some tests, particularly for age-standardised outcomes. This variation and these floor effects can pose a problem for comparing and combining study populations when different standardised measures have been used to assess individuals' cognitive abilities, for example combining results across studies to investigate genetic or other factors associated with cognitive abilities.

Cognitive markers of preclinical and prodromal Alzheimer's disease in Down syndrome.

Introduction: Down syndrome (DS) is associated with an almost universal development of Alzheimer's disease. Individuals with DS are therefore an important population for randomized controlled trials to prevent or delay cognitive decline, though it is essential to understand the time course of early cognitive changes.

Methods: We conducted the largest cognitive study to date with 312 adults with DS to assess age-related and Alzheimer's disease-related cognitive changes during progression from preclinical to prodromal dementia, and prodromal to clinical dementia.

Association of Dementia With Mortality Among Adults With Down Syndrome Older Than 35 Years.

Importance: This work quantifies the fatal burden of dementia associated with Alzheimer disease in individuals with Down syndrome (DS).

Objective: To explore the association of dementia associated with Alzheimer disease with mortality and examine factors associated with dementia in adults with DS.

Design, Settings And Participants: Prospective longitudinal study in a community setting in England.

Aging related cognitive changes associated with Alzheimer's disease in Down syndrome.

Objective: Individuals with Down syndrome (DS) have an extremely high genetic risk for Alzheimer's disease (AD), however, the course of cognitive decline associated with progression to dementia is ill-defined. Data-driven methods can estimate long-term trends from cross-sectional data while adjusting for variability in baseline ability, which complicates dementia assessment in those with DS.

Methods: We applied an event-based model to cognitive test data and informant-rated questionnaire data from 283 adults with DS (the largest study of cognitive functioning in DS to date) to estimate the sequence of cognitive decline and individuals' disease stage.

Neurofilament light as a blood biomarker for neurodegeneration in Down syndrome.

Background: Down syndrome (DS) may be considered a genetic form of Alzheimer's disease (AD) due to universal development of AD neuropathology, but diagnosis and treatment trials are hampered by a lack of reliable blood biomarkers. A potential biomarker is neurofilament light (NF-L), due to its association with axonal damage in neurodegenerative conditions.

Methods: We measured blood NF-L concentrations in 100 adults with DS using Simoa NF-light® assays, and we examined relationships with age as well as cross-sectional and longitudinal dementia diagnosis.

The LonDownS adult cognitive assessment to study cognitive abilities and decline in Down syndrome.

Background: Down syndrome (DS), the most common genetic cause of intellectual disability, is associated with an ultra-high risk of developing Alzheimer's disease. However, there is individual variability in the onset of clinical dementia and in baseline cognitive abilities prior to decline, particularly in memory, executive functioning, and motor coordination. The LonDownS Consortium aims to determine risk and protective factors for the development of dementia and factors relating to cognitive abilities in people with DS.

Developing an Informant Questionnaire for Cognitive Abilities in Down Syndrome: The Cognitive Scale for Down Syndrome (CS-DS).

Down syndrome (DS) is the most common genetic cause of intellectual disability (ID). Abilities relating to executive function, memory and language are particularly affected in DS, although there is a large variability across individuals. People with DS also show an increased risk of developing dementia.

Variation in the X-linked EFHC2 gene is associated with social cognitive abilities in males.

Females outperform males on many social cognitive tasks. X-linked genes may contribute to this sex difference. Males possess one X chromosome, while females possess two X chromosomes.