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1.
Am J Med Genet C Semin Med Genet ; 193(4): e32070, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37864360

ABSTRACT

Individuals with Down syndrome (DS) have been particularly impacted by respiratory conditions, such as pneumonia. However, the description of co-occurring recurrent infections, the response to pneumococcal immunization, and the association of these was previously unknown. We screened individuals with DS using an 11-item screener and prospectively collected pneumococcal titers and laboratory results. We found that the screener did not successfully predict which individuals with DS who would have inadequate pneumococcal titers. Thirty four of the 55 individuals with DS (62%) had abnormal pneumococcal titers demonstrating an inadequate response to routine immunization. In the absence of a valid screener, clinicians should consider screening all individuals with DS through the use of pneumococcal titers to 23 serotypes to assess vaccine response.


Subject(s)
Down Syndrome , Pneumonia , Humans , Down Syndrome/complications , Antibodies, Bacterial , Streptococcus pneumoniae , Pneumococcal Vaccines/therapeutic use
2.
Am J Med Genet A ; 191(9): 2300-2311, 2023 09.
Article in English | MEDLINE | ID: mdl-37340831

ABSTRACT

Plasma ceramide levels (henceforth, "ceramides") are biomarkers of some diseases that are comorbidities of Down syndrome (DS). We sought to determine if comorbidities in DS were associated with ceramides, studying a convenience cohort of 35 study participants, all ≥12 months old. To identify comorbidities, we reviewed the problem lists in electronic health records that were concurrent with sample collection. We placed clinically related comorbidities into one of five categories of comorbidities, henceforth, categories: obesity/overweight; autoimmune disease; congenital heart disease; bacterial infection; and central nervous system (CNS) condition. We measured the eight ceramides most frequently associated with disease using liquid chromatography-tandem mass spectrometry. We calculated a ceramide composite outcome score (CCOS) for each participant by normalizing each ceramide level to the mean for that level in the study population and then summing the normalized levels, to be proxy variable for all eight ceramides in aggregate. We used multivariable linear regression models adjusted for age and sex to test associations of categories with ceramides and with CCOSs. Post hoc, we realized that co-occurring comorbidities might interfere with establishing associations between predictor categories and ceramides and that stratified analyses might eliminate their influence on associations. We posited that CCOSs could be used to screen for associations of categories with multiple ceramides, since most diseases have been associated with more than one ceramide. We chose to omit in the stratified analyses the two categories that were the most different from one another in their associations with their CCOSs, having the most divergent regression coefficients (the highest positive and lowest negative coefficients). We first omitted one of these two divergent categories in a stratified analysis and tested in the remaining participants (those without a comorbidity in the interfering category) for associations of the other four categories with their CCOSs and then did the same for the other divergent category. In each of these two screening stratified analyses, we found one category was significantly associated with its CCOS. In the two identified categories, we then tested for associations with each of the eight ceramides, using the appropriate stratified analysis. Next, we sought to determine if the associations of the two categories with ceramides we found by omitting participants in the interfering categories held in our small sample for participants in the omitted categories as well. For each of the two categories, we therefore omitted participants without the interfering category and determined associations between the predictor category and individual ceramides in the remaining participants (those with a comorbidity in the interfering category). In the a priori analyses, autoimmune disease was inversely associated with C16 and CNS condition was inversely associated with C23. Obesity/overweight and CNS condition were the two categories with the most divergent regression coefficients (0.037 vs. -0.048). In post hoc stratified analyses, after omitting participants with obesity/overweight, thereby leaving participants without obesity/overweight, bacterial infection was associated with its CCOS and then with C14, C20, and C22. However, in the companion stratified analyses, omitting participants without obesity/overweight, thereby leaving participants with obesity/overweight, bacterial infection was not associated with any of the eight ceramides. Similarly, in post hoc stratified analyses after omitting participants with a CNS condition, thereby leaving participants without a CNS condition, obesity/overweight was associated with its CCOS and then with C14, C23, and C24. In the companion analyses, omitting participants without a CNS condition, thereby leaving participants with a CNS condition, obesity/overweight was inversely associated with C24.1. In conclusion, CNS and autoimmune disease were inversely associated with one ceramide each in a priori analyses. In post hoc analyses, we serendipitously omitted categories that interfered with associations of other categories with ceramides in stratified analyses. We found that bacterial infection was associated with three ceramides in participants without obesity/overweight and that obesity/overweight was associated with three ceramides in participants without a CNS condition. We therefore identified obesity/overweight and CNS conditions as potential confounders or effect modifiers for these associations. This is the first report of ceramides in DS and in human bacterial infection. Further study of ceramides in comorbidities of DS is justified.


Subject(s)
Down Syndrome , Overweight , Humans , Infant , Ceramides , Down Syndrome/complications , Down Syndrome/epidemiology , Comorbidity , Obesity/complications , Obesity/epidemiology
4.
Am J Med Genet A ; 191(3): 813-822, 2023 03.
Article in English | MEDLINE | ID: mdl-36538912

ABSTRACT

Individuals with Down syndrome (DS) are at increased risk for being overweight/obese, but the associated cardiometabolic risk (CR) is not clear. Cross-sectional anthropometric and clinical laboratory data from a multi-site, international cohort of individuals with DS were analyzed to determine cardiometabolic risk by reporting observed distributions of cardiometabolic biomarkers in overweight/obese individuals with DS throughout the lifespan. Descriptive statistics and regression analyses by age categories determined the distributive percentiles for cardiometabolic biomarkers and tested for adiposity as a predictor of CR. Across seven DS clinics, data were collected on 240 patients between the ages of 3 and 63 years, with one quarter overweight and three quarters obese among children and nearly all adults being obese. In children and adults, most cardiometabolic biomarker profiles showed distributive values within normal ranges. Blood lipids were positively associated with body mass index (BMI) in children (high density lipid-cholesterol, p = 0.01; low density lipid-cholesterol, p = 0.02). Levels of hs-CRP were elevated in both children and adults, with BMI positively associated with hs-CRP in adults with DS (p = 0.04). Liver enzyme values were positively associated with BMI in children and adults. The data suggest that in contrast to the general population, in individuals with Down syndrome, being overweight and obese does not appear to confer a significantly increased risk for cardiometabolic disease by biomarker profile. Individuals with DS who are overweight/obese appear to have unique cardiometabolic profiles unrelated to adiposity, notable for increased hs-CRP and normal HA1c levels.


Subject(s)
Cardiovascular Diseases , Down Syndrome , Metabolic Diseases , Humans , Child , Adult , Child, Preschool , Adolescent , Young Adult , Middle Aged , Overweight/complications , Overweight/epidemiology , C-Reactive Protein/analysis , Down Syndrome/complications , Down Syndrome/epidemiology , Cross-Sectional Studies , Risk Factors , Obesity/complications , Body Mass Index , Biomarkers , Lipids , Cardiovascular Diseases/epidemiology , Cardiovascular Diseases/etiology
5.
Am J Med Genet A ; 188(10): 3049-3062, 2022 10.
Article in English | MEDLINE | ID: mdl-35924793

ABSTRACT

Research to guide clinicians in the management of the devastating regression which can affect adolescents and young adults with Down syndrome is limited. A multi-site, international, longitudinal cohort of individuals with a clinical diagnosis of Unexplained Regression in Down syndrome (URDS) was collated through seven Down syndrome clinics. Tiered medical evaluation, a 28-item core symptom list, and interim management are described naturalistically. Improvement-defined by the percentage of baseline function on a Parent-reported Functional Score, overall improvement in symptoms on a Clinician-administered Functional Assessment, or report of management type being associated with improvement-was analyzed. Improvement rates using ECT, IVIG, and others were compared. Across seven clinics, 51 patients with URDS had regression at age 17.6 years, on average, and showed an average 14.1 out of 28 symptoms. Longitudinal improvement in function was achieved in many patients and the medical management, types of treatment, and their impact on function are described. Management with intravenous immunoglobulin (IVIG) was significantly associated with higher rate of improvement in symptoms at the next visit (p = 0.001). Our longitudinal data demonstrates that URDS is treatable, with various forms of clinical management and has a variable course. The data suggests that IVIG may be an effective treatment in some individuals. Our description of the management approaches used in this cohort lays the groundwork for future research, such as development of standardized objective outcome measure and creation of a clinical practice guideline for URDS.


Subject(s)
Down Syndrome , Adolescent , Down Syndrome/complications , Down Syndrome/epidemiology , Down Syndrome/therapy , Humans , Immunoglobulins, Intravenous/therapeutic use , Outcome Assessment, Health Care , Treatment Outcome , Young Adult
6.
Curr Biol ; 31(20): 4620-4626.e3, 2021 10 25.
Article in English | MEDLINE | ID: mdl-34411528

ABSTRACT

As humanity is facing the double challenge of species extinctions and climate change, designating parts of forests as protected areas is a key conservation strategy.1-4 Protected areas, encompassing 14.9% of the Earth's land surface and 19% of global forests, can prevent forest loss but do not do so perfectly everywhere.5-12 The reasons why protection only works in some areas are difficult to generalize: older and newer parks, protected areas with higher and lower suitability for agriculture, and more and less strict protection can be more effective at preventing forest loss than their counterparts.6,8,9,12-16 Yet predicting future forest loss within protected areas is crucial to proactive conservation. Here, we identify an early warning sign of subsequent forest loss, based on forest loss patterns in strict protected areas and their surrounding landscape worldwide, from 2000 to 2018.17,18 We found that a low level in the absolute forest cover immediately outside of a protected area signals a high risk of future forest loss inside the protected area itself. When the amount of forest left outside drops to <20%, the protected area is likely to experience rates of forest loss matching those in the wider landscape, regardless of its protection status (e.g., 5% loss outside will be matched by 5% loss inside). This knowledge could be used to direct funding to protected areas threatened by imminent forest loss, helping to proactively bolster protection to prevent forest loss, especially in countries where detailed information is lacking.


Subject(s)
Conservation of Natural Resources , Forests , Agriculture , Biodiversity , Climate Change , Extinction, Biological
7.
Front Neurol ; 12: 621637, 2021.
Article in English | MEDLINE | ID: mdl-33841297

ABSTRACT

Down syndrome disintegrative disorder (DSDD) is a condition of unknown etiology characterized by acute cognitive decline, catatonia, insomnia, and autistic features in individuals with Down syndrome. A prior report of four patients with DSDD suggested a potential autoimmune etiology based on the presence of autoantibodies and on successful treatment with immunotherapy that included intravenous immunoglobulin (IVIG). Herein, we present the case of an 8-year old girl who developed acute cognitive decline to a dementia-like state, insomnia, catatonia, and autistic features. In contrast to the four patients with DSDD above, she had no evidence of autoimmunity and presented at a younger age. Given the gravity of her acute deterioration and the exclusion of other etiologies, she was treated with immunotherapy presumptively. She responded with near complete resolution of symptoms, but demonstrated a pattern of mild decline as she approached each monthly dosing of IVIG and steroids, reversed by treatment. Mycophenolate mofetil (MMF) was therefore added, with stability throughout the month and the ability to taper off IVIG. After stopping IVIG, she had a mild recurrence of symptoms that again resolved with repeat IVIG followed by tapering off. Outcome was assessed at 2.5 years after presentation, at which time she was back to her premorbid condition, except for persistent tics off immunotherapy. This case supports the contention that patients with a rapid onset of severe symptoms consistent with DSDD, who have a thorough evaluation with the exclusion of other etiologies, may warrant a trial of immunotherapy with steroids, IVIG and/or other agents like MMF even in the absence of evidence of autoimmunity on standard evaluation.

8.
Int J Eat Disord ; 53(9): 1496-1505, 2020 09.
Article in English | MEDLINE | ID: mdl-32666600

ABSTRACT

OBJECTIVE: Eating disorders develop as a result of genetic and environmental factors. Given that they are multifactorial conditions with a genetic component, they fall within the scope of practice for genetic counseling, but people with these conditions are rarely referred. The purpose of this study was to explore the perceptions of causes of eating disorders, recurrence risk, and interest in genetic counseling and testing among individuals with eating disorders. METHOD: An online survey comprising both multiple choice and free form text questions, vignettes about genetic counseling, and the ED100K (validated eating disorder diagnostic questionnaire) was shared via support organizations and prominent bloggers in the eating disorders community to recruit individuals with a personal history of an eating disorder from November 2018 to February 2019. RESULTS: In total, 107 participants completed the survey. They perceived that both experiences and genetics were important factors in the development of their eating disorder. All responding participants overestimated the risk for recurrence of eating disorders in children, often by a large margin, and a notable minority reported that their experience with an eating disorder had a negative influence on their childbearing decisions. After imagined experience of genetic counseling, participants reported significantly decreased feelings of stigma, shame, and guilt. Most participants expressed interest in genetic counseling; fewer were interested in genetic testing. DISCUSSION: Genetic counseling may benefit individuals with eating disorders by providing accurate recurrence risk information and reducing feelings of guilt, stigma, and shame, which may in turn encourage earlier support seeking and recovery.


Subject(s)
Counseling/methods , Feeding and Eating Disorders/diagnosis , Genetic Testing/methods , Adolescent , Adult , Feeding and Eating Disorders/genetics , Female , Humans , Male , Middle Aged , Perception , Risk Factors , Surveys and Questionnaires , Young Adult
9.
Ecology ; 101(5): e02998, 2020 05.
Article in English | MEDLINE | ID: mdl-32012254

ABSTRACT

Understanding how severe disturbances and their interactions affect forests is key to projecting ecological change under a warming climate. Substantial increases in some biotic disturbances, such as bark beetle outbreaks, in temperate forest ecosystemsmay compromise recovery to a forest vegetation type (i.e., physiognomic recovery or resilience), especially if subsequent biotic disturbances (e.g., herbivory) alter recovery mechanisms. From 2005 to 2017, severe outbreaks (>90% mortality) of spruce bark beetles (SB, Dendroctonus rufipennis) affected Engelmann spruce (Picea engelmannii) across 325,000 ha of spruce and subalpine fir (Abies lasiocarpa) forest in the southern Rocky Mountains, USA. Concurrently, an outbreak of western balsam bark beetle (WBBB, Dryocoetes confuses) infested subalpine fir across at least 47,000 of these hectares. We explored the capacity of 105 stands affected by one or two bark beetle outbreaks and browsing of juvenile trees by ungulates to return to a forest vegetation type in the context of pre-outbreak forest conditions and topography. Nine initial forest trajectories (i.e., at least several decades) were identified from four pre-outbreak forest types affected by three biotic disturbances that occurred at different spatial scales and severities. Most stands (86%) contained surviving nonhost adult trees in the main canopy (fir and aspen [Populus tremuloides]) and many surviving juveniles of all species, implying that they are currently on a trajectory for physiognomic recovery. Stands composed exclusively of large-diameter spruce were affected by a severe SB outbreak and were most vulnerable to a transition to a low-density forest, below regional stocking levels (<370 trees/ha). Greater pre-outbreak stand structural complexity and species diversity were key traits of stands with a higher potential for physiognomic recovery. However, all multispecies stands shifted in relative composition of the main canopy to nonhost species, suggesting low potential for compositional recovery over the next several decades. Most post-outbreak stands (86%) exceeded regional stocking levels with trees taller than the browse zone (<2 m). As such, ungulate browsing on over half of all juveniles will primarily affect the rate of infilling of the forest canopy and preferential browsing of more palatable species will influence the composition of the future forest canopy.


Subject(s)
Coleoptera , Picea , Animals , Balsams , Disease Outbreaks , Forests , Plant Bark , Trees
10.
Genet Med ; 22(2): 317-325, 2020 02.
Article in English | MEDLINE | ID: mdl-31417190

ABSTRACT

PURPOSE: Current American Academy of Pediatrics guidelines for children with Down syndrome (DS) recommend a complete blood count (CBC) at birth and hemoglobin annually to screen for iron deficiency (ID) and ID anemia (IDA) in low-risk children. We aimed to determine if macrocytosis masks the diagnosis of ID/IDA and to evaluate the utility of biochemical and red blood cell indices for detecting ID/IDA in DS. METHODS: We reviewed data from 856 individuals from five DS specialty clinics. Data included hemoglobin, mean corpuscular volume, red cell distribution width (RDW), percent transferrin saturation (TS), ferritin, and c-reactive protein. Receiver operating characteristic curves were calculated. RESULTS: Macrocytosis was found in 32% of the sample. If hemoglobin alone was used for screening, all individuals with IDA would have been identified, but ID would have been missed in all subjects. RDW had the highest discriminability of any single test for ID/IDA. The combination of RDW with ferritin or TS led to 100% sensitivity, and RDW combined with ferritin showed the highest discriminability for ID/IDA. CONCLUSION: We provide evidence to support that a CBC and ferritin be obtained routinely for children over 1 year old with DS rather than hemoglobin alone for detection of ID.


Subject(s)
Anemia, Iron-Deficiency/diagnosis , Down Syndrome/metabolism , Ferritins/analysis , Anemia/diagnosis , C-Reactive Protein/analysis , Child , Child, Preschool , Erythrocyte Indices/genetics , Erythrocytes, Abnormal/metabolism , Female , Ferritins/blood , Hematologic Diseases/metabolism , Hemoglobins/analysis , Humans , Infant , Iron/metabolism , Male , Mass Screening/methods , ROC Curve
11.
Genet Med ; 22(4): 767-776, 2020 04.
Article in English | MEDLINE | ID: mdl-31767984

ABSTRACT

PURPOSE: An entity of regression in Down syndrome (DS) exists that affects adolescents and young adults and differs from autism spectrum disorder and Alzheimer disease. METHODS: Since 2017, an international consortium of DS clinics assembled a database of patients with unexplained regression and age- and sex-matched controls. Standardized data on clinical symptoms and tiered medical evaluations were collected. Elements of the proposed definition of unexplained regression in DS were analyzed by paired comparisons between regression cases and matched controls. RESULTS: We identified 35 patients with DS and unexplained regression, with a mean age at regression of 17.5 years. Diagnostic features differed substantially between regression cases and matched controls (p < 0.001 for all but externalizing behaviors). Patients with regression had four times as many mental health concerns (p < 0.001), six times as many stressors (p < 0.001), and seven times as many depressive symptoms (p < 0.001). Tiered medical evaluation most often identified abnormalities in vitamin D 25-OH levels, polysomnograms, thyroid peroxidase antibodies, and celiac screens. Analysis of the subset of patients with nondiagnostic medical evaluations reinforced the proposed definition. CONCLUSIONS: Our case-control evidence supports a proposed definition of unexplained regression in Down syndrome. Establishing this clinical definition supports future research and investigation of an underlying mechanism.


Subject(s)
Autism Spectrum Disorder , Down Syndrome , Adolescent , Case-Control Studies , Databases, Factual , Down Syndrome/diagnosis , Down Syndrome/epidemiology , Humans , Young Adult
13.
Dev Med Child Neurol ; 61(7): 847-851, 2019 07.
Article in English | MEDLINE | ID: mdl-30548468

ABSTRACT

Down syndrome disintegrative disorder (DSDD) is an increasingly identified condition characterized by cognitive decline, autistic characteristics, insomnia, catatonia, and psychosis in adolescents and young adults with Down syndrome. Previously we reported a higher rate of autoimmune thyroid disease in these patients compared with unaffected individuals with Down syndrome. We therefore hypothesized DSDD may in some cases be immune-mediated. Here we report four cases of DSDD treated with immunotherapy. Families were interviewed retrospectively for symptoms of cognitive decline, autism, catatonia, psychosis, and insomnia before and after treatment, using established scales where possible. Medical records were reviewed for evaluations and treatment. All four patients received intravenous immunoglobulin with or without additional immunotherapy. Significant improvements were seen in catatonia, insomnia, autistic features, cognition, and psychosis. In this small case series of patients with autoimmunity, core symptoms of DSDD improved significantly after immunotherapy. This supports the hypothesis that, in some patients, DSDD is immune-mediated. Immunotherapy should be considered in the treatment of DSDD, particularly in patients with a history of autoimmunity. WHAT THIS PAPER ADDS: Immunotherapy may improve symptoms of catatonia, insomnia, autism severity, cognitive decline, and psychosis in Down syndrome disintegrative disorder.


INMUNOTERAPIA EN PACIENTES SELECCIONADOS CON TRASTORNO DESINTEGRATIVO DEL SÍNDROME DE DOWN: El trastorno desintegrativo del síndrome de Down (TDSD) es una afección cada vez más identificada que se caracteriza por deterioro cognitivo, características autistas, insomnio, catatonia y psicosis en adolescentes y adultos jóvenes con síndrome de Down. Anteriormente informamos una tasa más alta de enfermedad tiroidea autoinmune en estos pacientes en comparación con las personas no afectadas con síndrome de Down. Por lo tanto, hipotetizamos que el TDSD puede, en algunos casos, estar inmunomediado. Aquí presentamos cuatro casos de TDSD tratados con inmunoterapia. Las familias fueron entrevistadas retrospectivamente para los síntomas de deterioro cognitivo, autismo, catatonía, psicosis e insomnio antes y después del tratamiento, utilizando escalas establecidas cuando sea posible. Los registros médicos fueron revisados ​​para evaluaciones y tratamiento. Los cuatro pacientes recibieron inmunoglobulina intravenosa con o sin inmunoterapia adicional. Se observaron mejoras significativas en catatonia, insomnio, características autistas, cognición y psicosis. En esta pequeña serie de casos de pacientes con autoinmunidad, los síntomas centrales de la TDSD mejoraron significativamente después de la inmunoterapia. Esto apoya la hipótesis de que, en algunos pacientes, la TDSD está inmunomediada. La inmunoterapia debe considerarse en el tratamiento de la TDSD, particularmente en pacientes con antecedentes de autoinmunidad.


IMUNOTERAPIA EM PACIENTES SELECIONADOS COM SÍNDROME DE DOWN E TRANSTORNO DESINTEGRATIVO: O transtorno desintegrativo na síndrome de Down (TDSD) é uma condição crescentemente identificada, caracterizada por declínio cognitivo, características autistas, insônia, catatonia, e psicose em adolescente e jovens adultos com síndrome de Down. Nós relatamos previamente uma taxa maior de doença autoimune da tireóide nestes pacientes comparados com indivíduos com síndrome de Down não afetados. Portanto, hipotetizamos que o TDSD pode, em alguns casos, ser imune-mediado. Aqui reportamos quatro casos de TDSD tratados com imunoterapia. As famílias foram entrevistadas retrospectivamente quanto a sintomas de declínio cognitivo, autismo, catatonia, psicose, e insônia antes e depois do tratamento, usando escalas estabelecidas quando possível. Os registros médicos foram revisados quanto a avaliações e tratamento. Todos os quatro pacientes receberam imunoglobulina intravenosa com ou sem imunoterapia adicional. Melhoras significativas foram vistas na catatonia, aspectos autistas, cognição, e psicose. Nesta pequena série de casos de pacientes com auto-imunidade, os sintomas centrais de TDSD melhoraram significativament após imunoterapia. Isso apóia a hipótese de que, em alguns pacientes, o TDSD é imuno-mediado. A imunoterapia deve ser considerada no tratamento do TDSD, particularmente em pacientes com história de autoimunidade.


Subject(s)
Autoimmune Diseases/therapy , Down Syndrome/therapy , Immunotherapy , Adult , Autoimmune Diseases/immunology , Autoimmune Diseases/psychology , Down Syndrome/immunology , Down Syndrome/psychology , Female , Humans , Immunoglobulins, Intravenous/therapeutic use , Immunologic Factors/therapeutic use , Male , Young Adult
14.
Am J Med Genet A ; 179(1): 85-93, 2019 01.
Article in English | MEDLINE | ID: mdl-30569586

ABSTRACT

Measures of adaptive behavior are important in the assessment and treatment of individuals with intellectual disabilities (ID). The purpose of the current study was to evaluate the stability of an established and a novel measure of adaptive behavior over time, and their suitability as outcome measures in clinical trials targeting individuals with Down syndrome (DS). This 6-month, longitudinal, noninterventional, multinational study included adolescents (12-17 years) and adults (18-30 years) with DS. Participants were from seven countries (11 different sites) with English, Spanish and French as their native language. The Vineland Adaptive Behavior Scales-II (VABS-II) and a newly developed Clinician Global Impression (CGI) scale were administered at baseline, 1 and 6 months. Adults had lower composite standard scores on all domains of the VABS-II compared with adolescents. The communication domain was a weakness relative to the socialization and daily living skills domains on the VABS-II and the CGI-Severity scale. These findings were stable over 6 months, as exhibited by high intraclass correlations (>0.75). These results provide valuable baseline data for use in trial design and endpoint selection for studies including individuals with DS. ClinicalTrials.gov identifier: NCT01580384.


Subject(s)
Adaptation, Psychological , Down Syndrome/genetics , Intellectual Disability/physiopathology , Activities of Daily Living/psychology , Adolescent , Adult , Child , Down Syndrome/physiopathology , Female , Humans , Intellectual Disability/psychology , Longitudinal Studies , Male , Socialization , Young Adult
15.
Glob Chang Biol ; 25(3): 869-884, 2019 03.
Article in English | MEDLINE | ID: mdl-30570807

ABSTRACT

Future changes in climate are widely anticipated to increase fire frequency, particularly in boreal forests where extreme warming is expected to occur. Feedbacks between vegetation and fire may modify the direct effects of warming on fire activity and shape ecological responses to changing fire frequency. We investigate these interactions using extensive field data from the Boreal Shield of Saskatchewan, Canada, a region where >40% of the forest has burned in the past 30 years. We use geospatial and field data to assess the resistance and resilience of eight common vegetation states to frequent fire by quantifying the occurrence of short-interval fires and their effect on recovery to a similar vegetation state. These empirical relationships are combined with data from published literature to parameterize a spatially explicit, state-and-transition simulation model of fire and forest succession. We use this model to ask if and how: (a) feedbacks between vegetation and wildfire may modify fire activity on the landscape, and (b) more frequent fire may affect landscape forest composition and age structure. Both field and GIS data suggest the probability of fire is low in the initial decades after fire, supporting the hypothesis that fuel accumulation may exert a negative feedback on fire frequency. Field observations of pre- and postfire composition indicate that switches in forest state are more likely in conifer stands that burn at a young age, supporting the hypothesis that resilience is lower in immature stands. Stands dominated by deciduous trees or jack pine were generally resilient to fire, while mixed conifer and well-drained spruce forests were less resilient. However, simulation modeling suggests increased fire activity may result in large changes in forest age structure and composition, despite the feedbacks between vegetation-fire likely to occur with increased fire activity.


Subject(s)
Taiga , Tracheophyta/parasitology , Wildfires , Climate Change , Environmental Monitoring , Models, Theoretical , Saskatchewan , Species Specificity , Time Factors , Tracheophyta/classification , Tracheophyta/growth & development
16.
Nat Commun ; 9(1): 4355, 2018 10 19.
Article in English | MEDLINE | ID: mdl-30341309

ABSTRACT

Increasing evidence indicates that forest disturbances are changing in response to global change, yet local variability in disturbance remains high. We quantified this considerable variability and analyzed whether recent disturbance episodes around the globe were consistently driven by climate, and if human influence modulates patterns of forest disturbance. We combined remote sensing data on recent (2001-2014) disturbances with in-depth local information for 50 protected landscapes and their surroundings across the temperate biome. Disturbance patterns are highly variable, and shaped by variation in disturbance agents and traits of prevailing tree species. However, high disturbance activity is consistently linked to warmer and drier than average conditions across the globe. Disturbances in protected areas are smaller and more complex in shape compared to their surroundings affected by human land use. This signal disappears in areas with high recent natural disturbance activity, underlining the potential of climate-mediated disturbance to transform forest landscapes.


Subject(s)
Climate Change , Ecosystem , Forests , Remote Sensing Technology
17.
Ecology ; 99(3): 567-575, 2018 03.
Article in English | MEDLINE | ID: mdl-29469981

ABSTRACT

In the absence of broad-scale disturbance, many temperate coniferous forests experience successful seedling establishment only when abundant seed production coincides with favorable climate. Identifying the frequency of past establishment events and the climate conditions favorable for seedling establishment is essential to understanding how climate warming could affect the frequency of future tree establishment events and therefore future forest composition or even persistence of a forest cover. In the southern Rocky Mountains, USA, research on the sensitivity of establishment of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa)-two widely distributed, co-occurring conifers in North America-to climate variability has focused on the alpine treeline ecotone, leaving uncertainty about the sensitivity of these species across much of their elevation distribution. We compared annual germination dates for >450 Engelmann spruce and >500 subalpine fir seedlings collected across a complex topographic-moisture gradient to climate variability in the Colorado Front Range. We found that Engelmann spruce and subalpine fir established episodically with strong synchrony in establishment events across the study area. Broad-scale establishment events occurred in years of high soil moisture availability, which were characterized by above-average snowpack and/or cool and wet summer climatic conditions. In the recent half of the study period (1975-2010), a decrease in the number of fir and spruce establishment events across their distribution coincided with declining snowpack and a multi-decadal trend of rising summer temperature and increasing moisture deficits. Counter to expected and observed increases in tree establishment with climate warming in maritime subalpine forests, our results show that recruitment declines will likely occur across the core of moisture-limited subalpine tree ranges as warming drives increased moisture deficits.


Subject(s)
Abies , Picea , Colorado , North America , Trees
18.
Rev. Síndr. Down ; 35(135): 125-134, dic. 2017. ilus, tab
Article in Spanish | IBECS | ID: ibc-170217

ABSTRACT

Pese al creciente número de ensayos clínicos desarrollados para evaluar la cognición en el síndrome de Down, sus resultados para identificar intervenciones eficaces han sido muy limitados hasta la fecha. Las intervenciones en los modelos animales, con frecuencia muy favorables, no se han visto reflejadas en los ensayos clínicos. Esta revisión describe los resultados de los principales ensayos realizados. Ofrece consideraciones a los investigadores y describe estrategias a la industria farmacéutica para que se implique crecientemente en el descubrimiento de fármacos en el síndrome de Down


Although an increasing number of clinical trials have been developed for cognition in Down syndrome, there has been limited success to date in identifying effective interventions. This review describes the progression from pre-clinical studies with mouse models to human clinical trials research using pharmacological interventions to improve cognition and adaptive functioning in Down syndrome. We also provide considerations for investigators when conducting human clinical trials and describe strategies for the pharmaceutical industry to advance the field in drug discovery for Down syndrome


Subject(s)
Humans , Cognition Disorders/drug therapy , Adjustment Disorders/drug therapy , Down Syndrome/drug therapy , Cognition , Adaptation, Psychological , Rivastigmine/pharmacokinetics , Piracetam/pharmacokinetics , Memantine/pharmacokinetics , Drugs, Investigational
19.
Am J Med Genet A ; 173(11): 3058-3066, 2017 Nov.
Article in English | MEDLINE | ID: mdl-28857390

ABSTRACT

We systematically reviewed the measures used in pharmaceutical trials in children/adults with Down syndrome without dementia. Our purpose was to identify developmentally appropriate outcome measures capable of detecting changes in cognitive and adaptive functioning in this population. Eleven studies were included and used diverse outcome measures across the domains of language, memory, attention, behavior, and executive/adaptive functioning. Our results highlight the challenges in selecting measures capable of capturing improvements in pharmaceutical trials in individuals with DS. We offer suggestions to enhance future research, including: conducting studies with larger samples of participants with a range of developmental abilities; modifying existing/developing novel outcome measures; incorporating advances from related areas and DS observational studies; and considering alternative analytic techniques to characterize treatment effects.


Subject(s)
Cognition/drug effects , Cognitive Dysfunction/drug therapy , Dementia/drug therapy , Down Syndrome/drug therapy , Attention/physiology , Cognitive Dysfunction/genetics , Cognitive Dysfunction/physiopathology , Dementia/genetics , Dementia/pathology , Down Syndrome/genetics , Down Syndrome/physiopathology , Humans , Memory/drug effects , Memory/physiology
20.
Am J Med Genet A ; 173(11): 3029-3041, 2017 Nov.
Article in English | MEDLINE | ID: mdl-28884975

ABSTRACT

Although an increasing number of clinical trials have been developed for cognition in Down syndrome, there has been limited success to date in identifying effective interventions. This review describes the progression from pre-clinical studies with mouse models to human clinical trials research using pharmacological interventions to improve cognition and adaptive functioning in Down syndrome. We also provide considerations for investigators when conducting human clinical trials and describe strategies for the pharmaceutical industry to advance the field in drug discovery for Down syndrome. Future research focusing on earlier pharmaceutical interventions, development of appropriate outcome measures, and greater collaboration between industry, academia, advocacy, and regulatory groups will be important for addressing limitations from prior studies and developing potential effective interventions for cognition in Down syndrome.


Subject(s)
Cognition/drug effects , Cognitive Dysfunction/drug therapy , Down Syndrome/drug therapy , Animals , Cognitive Dysfunction/genetics , Cognitive Dysfunction/physiopathology , Down Syndrome/genetics , Down Syndrome/physiopathology , Humans , Mice
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