Towards onset prevention of cognition decline in adults with Down syndrome (The TOP-COG study): A pilot randomised controlled trial

Down Syndrome Biobank Consortium: A perspective

Individuals with Down syndrome (DS) have a partial or complete trisomy of chromosome 21, resulting in an increased risk for early-onset Alzheimer's disease (AD)-type dementia by early midlife. Despite ongoing clinical trials to treat late-onset AD, individuals with DS are often excluded. Furthermore, timely diagnosis or management is often not available. Of the genetic causes of AD, people with DS represent the largest cohort. Currently, there is a knowledge gap regarding the underlying neurobiological mechanisms of DS-related AD (DS-AD), partly due to limited access to well-characterized brain tissue and biomaterials for research. To address this challenge, we created an international consortium of brain banks focused on collecting and disseminating brain tissue from persons with DS throughout their lifespan, named the Down Syndrome Biobank Consortium (DSBC) consisting of 11 biobanking sites located in Europe, India, and the USA. This perspective describes the DSBC harmonized protocols and tissue dissemination goals.

The use of the cambridge neuropsychological test automated battery for people born with Down syndrome and those born premature: A comparative systematic review

This review aimed to investigate the use of the Cambridge Neuropsychological Automated Testing Battery (CANTAB) for people at risk of cognitive impairment, especially those born with Down syndrome and those born preterm. Six databases were searched according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards, in addition to the bibliography index listed in the CANTAB site. Twenty four studies regarding Down syndrome and 17 regarding prematurity were reviewed and are here described. Both cognitive profiles were described, and their performance was compared on specific tasks and CANTAB tests. In this battery of tests, people with Down syndrome usually present impaired key cognitive domains, such as episodic memory and recognition memory. Results were presented considering general aspects described in the studies, specific findings such as dementia, the role of genetics, and cognitive profile, among other descriptions. Comparability between both populations in future studies is discussed.

Long-Term Effects of SARS-CoV-2 in the Brain: Clinical Consequences and Molecular Mechanisms

Numerous investigations have demonstrated significant and long-lasting neurological manifestations of COVID-19. It has been suggested that as many as four out of five patients who sustained COVID-19 will show one or several neurological symptoms that can last months after the infection has run its course. Neurological symptoms are most common in people who are less than 60 years of age, while encephalopathy is more common in those over 60. Biological mechanisms for these neurological symptoms need to be investigated and may include both direct and indirect effects of the virus on the brain and spinal cord. Individuals with Alzheimer's disease (AD) and related dementia, as well as persons with Down syndrome (DS), are especially vulnerable to COVID-19, but the biological reasons for this are not clear. Investigating the neurological consequences of COVID-19 is an urgent emerging medical need, since close to 700 million people worldwide have now had COVID-19 at least once. It is likely that there will be a new burden on healthcare and the economy dealing with the long-term neurological consequences of severe SARS-CoV-2 infections and long COVID, even in younger generations. Interestingly, neurological symptoms after an acute infection are strikingly similar to the symptoms observed after a mild traumatic brain injury (mTBI) or concussion, including dizziness, balance issues, anosmia, and headaches. The possible convergence of biological pathways involved in both will be discussed. The current review is focused on the most commonly described neurological symptoms, as well as the possible molecular mechanisms involved.

Proxy-report in individuals with intellectual disability: A scoping review

BACKGROUND

Views can be collected from individuals (self-report) or others on their behalf (proxy-report).

OBJECTIVE

We aimed to review the literature on methods and statistical approaches used to evaluate observer versus self-report responses from individuals with intellectual disability or Down syndrome.

METHODS

A series of key questions related to statistical approaches and data collection methods were formulated a priori to inform the search strategy and review process. These addressed the topics of self-report in individuals with intellectual disability, including Down syndrome. Using the National Library of Medicine database, PubMed, detailed literature searches were performed. The quality of available evidence was then evaluated, the existing literature was summarised, and knowledge gaps and research needs were identified.

RESULTS

Fifty relevant original articles were identified which addressed at least one key question. Study details, including: research design, internal validity, external validity, and relevant results are presented. Review of studies of individuals with intellectual disability which used a variety of statistical approaches showed mixed agreement between self-report and proxy-report.

CONCLUSION

Few studies identified to-date have used self-report from individuals with Down syndrome, but lessons from the existing intellectual disability literature can guide researchers to incorporate self-report from individuals with Down syndrome in the future.

The implications of exosomes in pregnancy: emerging as new diagnostic markers and therapeutics targets

Extracellular vehicles (EVs) are a heterogeneous group of cell and membranous particles originating from different cell compartments. EVs participate in many essential physiological functions and mediate fetal-maternal communications. Exosomes are the smallest unit of EVs, which are delivered to the extracellular space. Exosomes can be released by the umbilical cord, placenta, amniotic fluid, and amniotic membranes and are involved in angiogenesis, endothelial cell migration, and embryo implantation. Also, various diseases such as gestational hypertension, gestational diabetes mellitus (GDM), preterm birth, and fetal growth restriction can be related to the content of placental exosomes during pregnancy. Due to exosomes' ability to transport signaling molecules and their effect on sperm function, they can also play a role in male and female infertility. In the new insight, exosomal miRNA can diagnose and treat infertilities disorders. In this review, we focused on the functions of exosomes during pregnancy.

Tiny Toes to Tau Tangles: Down's Syndrome and Its Association With Alzheimer's Disease

Down’s syndrome (DS) is a common genetic condition caused by the trisomy of chromosome 21, which leads to the development of many multisystemic complications, early-onset Alzheimer’s disease (AD) being one of its most common complications. In this article, we have performed an intensive literature review that established a strong relationship between AD and DS. These two conditions are clubbed pathologically, clinically, and diagnostically to understand the association between AD and DS. This article focuses on understanding the impact of AD on a DS patient on both clinical and pathological levels and exploring some advanced treatment modalities. It has also emphasized the importance of early screening and diagnosis for AD in this group of patients to prevent AD development. Regular monitoring, early diagnosis, and a proper treatment plan can slow the AD occurrence in DS patients.

Aging with Down Syndrome-Where Are We Now and Where Are We Going?

Down syndrome (DS) is a form of accelerated aging, and people with DS are highly prone to aging-related conditions that include vascular and neurological disorders. Due to the overexpression of several genes on Chromosome 21, for example genes encoding amyloid precursor protein (APP), superoxide dismutase (SOD), and some of the interferon receptors, those with DS exhibit significant accumulation of amyloid, phospho-tau, oxidative stress, neuronal loss, and neuroinflammation in the brain as they age. In this review, we will summarize the major strides in this research field that have been made in the last few decades, as well as discuss where we are now, and which research areas are considered essential for the field in the future. We examine the scientific history of DS bridging these milestones in research to current efforts in the field. We extrapolate on comorbidities associated with this phenotype and highlight clinical networks in the USA and Europe pursuing clinical research, concluding with funding efforts and recent recommendations to the NIH regarding DS research.

Exosome release and cargo in Down syndrome

Down syndrome (DS) is a multisystem disorder affecting 1 in 800 births worldwide. Advancing technology, medical treatment, and social intervention have dramatically increased life expectancy, yet there are many etiologies of this disorder that are in need of further research. The advent of the ability to capture extracellular vesicles (EVs) in blood from specific cell types allows for the investigation of novel intracellular processes. Exosomes are one type of EVs that have demonstrated great potential in uncovering new biomarkers of neurodegeneration and disease, and also that appear to be intricately involved in the transsynaptic spread of pathogenic factors underlying Alzheimer's disease and other neurological diseases. Exosomes are nanosized vesicles, generated in endosomal multivesicular bodies (MVBs) and secreted by most cells in the body. Since exosomes are important mediators of intercellular communication and genetic exchange, they have emerged as a major research focus and have revealed novel biological sequelae involved in conditions afflicting the DS population. This review summarizes current knowledge on exosome biology in individuals with DS, both early in life and in aging individuals. Collectively these studies have demonstrated that complex multicellular processes underlying DS etiologies may include abnormal formation and secretion of extracellular vesicles such as exosomes.

A pilot randomised controlled trial of community-led ANtipsychotic Drug REduction for Adults with Learning Disabilities

BACKGROUND

Data suggest that approximately 50,000 adults with learning disabilities (LDs) in England and Wales are currently prescribed antipsychotic medication. Illness in this population is common, including significant rates of challenging behaviour and mental illness, but there is particular concern over the use of antipsychotics prescribed for reasons other than the treatment of psychosis. Control of challenging behaviour is the primary reason why such medications are prescribed despite the absence of good evidence for any therapeutic effect for this purpose.

OBJECTIVES

To assess the feasibility of recruitment and retention and to explore non-efficacy-based barriers to a blinded antipsychotic medication withdrawal programme for adults with LDs without psychosis compared with treatment as usual. A secondary objective was to compare trial arms regarding clinical outcomes.

DESIGN

A two-arm individually randomised double-blind placebo-controlled drug reduction trial.

SETTING

Recruitment was through community learning disability teams (CLDTs) in south Wales and south-west England.

PARTICIPANTS

Adults with LDs who are prescribed risperidone for treatment of challenging behaviour with no known current psychosis or previous recurrence of psychosis following prior drug reduction.

INTERVENTION

A double-blind drug reduction programme leading to full withdrawal within 6 months. Treatment in the intervention group was gradually reduced over a 6-month period and then maintained at the same level for a further 3 months, still under blind conditions. In the control group, the baseline level of medication was maintained throughout the 9-month period. The blind was broken at 9 months, following final data collection.

MAIN OUTCOME MEASURES

Feasibility outcomes were (1) the number and proportion of general practices/CLDTs that progressed from initial approach to recruitment of participants and (2) the number and proportion of recruited participants who progressed through the various stages of the study. Trial arms were also compared regarding clinical outcomes, the Modified Overt Aggression Scale, the Aberrant Behaviour Checklist, the Psychiatric Assessment Schedule for Adults with Developmental Disability checklist, the Antipsychotic Side-effect Checklist, the Dyskinesia Identification System Condensed User Scale, the Client Service Receipt Inventory, use of other interventions to manage challenging behaviour, use of as-required (pro re nata) medication and level of psychotropic medication use.

RESULTS

Of the 22 participants randomised (intervention, n = 11; control, n = 11), 13 (59%) achieved progression through all four stages of reduction. Follow-up data at 6 and 9 months were obtained for 17 participants (intervention, n = 10; and control, n = 7; 77% of those randomised). There were no clinically important changes in participants' levels of aggression or challenging behaviour at the end of the study. There were no expedited safety reports. Four adverse events and one serious adverse event were reported during the trial.

LIMITATIONS

Recruitment was challenging, which was largely a result of difficulty in identifying appropriate persons to consent and carer concerns regarding re-emergence of challenging behaviour. Reduced recruitment meant that the full trial became an exploratory pilot study.

CONCLUSIONS

The results indicate that drug reduction is possible and safe. However, concerns about taking part were probably exacerbated by limited availability of alternative (behavioural) interventions to manage behaviour; therefore, focused support and alternative interventions are required. The results of the qualitative study provide important insights into the experiences of people taking part in drug reduction studies that should influence future trial development.

FUTURE WORK

We recommend that further work focuses on support for practitioners, carers and patients in reducing antipsychotic medication.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN38126962.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 47. See the NIHR Journals Library website for further project information.

Cognitive decline and dementia in Down syndrome

PURPOSE OF REVIEW

Alzheimer's disease is most likely universal in older individuals with Down syndrome, due to having three copies of the amyloid precursor protein gene, resulting in amyloid-beta plaque deposition. Down syndrome is an important population in which to consider clinical trials of treatments to prevent or delay the development of dementia. However, assessment of subtler cognitive changes is challenging due to the presence of intellectual disability.

RECENT FINDINGS

Recent research confirmed that older adults with Down syndrome often present with cognitive decline: more than 80% may experience dementia by age 65 years. Efforts have been made to improve and validate neuropsychological assessment and to describe the relationship with comorbidities such as epilepsy and haemorrhagic stroke. There have also been advances in biomarkers such as neuroimaging using amyloid PET.

SUMMARY

Clinical trials of treatments, particularly in the presymptomatic phase of Alzheimer's disease, are important to consider in individuals with Down syndrome given their high dementia burden, and may also serve as proof of concept for other forms of Alzheimer's disease. However, further work is required to improve outcome measures and better understand the biomarkers of progression of disorder and their relationship with symptom development during the presymptomatic period.