Unexplained regression in Down syndrome: 35 cases from an international Down syndrome database

Down Syndrome and Autoimmune Disease

Down syndrome is the most common genetic cause of intellectual disability and has previously been associated with a variety of autoimmune disorders affecting multiple organ systems. The high prevalence of autoimmune disease, in conjunction with other inflammatory and infectious diseases, in this population suggests an intrinsic immune dysregulation associated with triplication of chromosome 21. Emerging data on the role of chromosome 21 in interferon activation, cytokine production, and activation of B-cell mediated autoimmunity are emerging hypotheses that may explain the elevated prevalence of autoimmune thyroid disease, celiac disease, type I diabetes, autoimmune skin disease, and a variety of autoimmune neurologic conditions. As the life expectancy for individuals with Down syndrome increases, knowledge of the epidemiology, clinical features, management and underlying causes of these conditions will become increasingly important. Disorders such as Hashimoto's thyroiditis are prevalent in between 13 and 34% of individuals with Down syndrome but only 3% of the neurotypical population, a pattern similarly recognized in individuals with Celiac Disease (5.8% v 0.5-2%), alopecia areata (27.7% v. 2%), and vitiligo (4.4% v. 0.05-1.55%), respectively. Given the chronicity of autoimmune conditions, early identification and management can significantly impact the quality of life of individuals with Down syndrome. This comprehensive review will highlight common clinical autoimmune conditions observed in individuals with Down syndrome and explore our current understanding of the mechanisms of disease in this population.

De novo variants in immune regulatory genes in Down syndrome regression disorder

BACKGROUND

Down Syndrome Regression Disorder (DSRD) is a rare and poorly understood disorder of the central nervous system, characterized by acute or subacute neuropsychiatric symptoms in previously healthy individuals with Down syndrome (DS). Many patients exhibit immunotherapy-responsiveness, indicative of immune dysregulation as a potential underlying etiology. While hypotheses are emerging regarding the role of interferon signaling in DSRD and other autoimmune conditions associated with DS, it is unclear why a small subset of individuals with DS develop DSRD. The aim of this study was to investigate genes of immune regulation in persons with DSRD.

METHODS

This study included individuals with DSRD aged 10-30 years with trio exome sequencing performed during the diagnostic work up. Descriptive statistics and univariate analysis (Chi-square and Fisher's exact test) were used to describe and compare the characteristics of individuals with and without variants.

RESULTS

Forty-one individuals with DSRD had trio exome sequencing results. Eight (20%) had heterozygous de novo variants of immune regulatory genes, with four variants being pathogenic or likely pathogenic (UNC13D, XIAP, RNASEH2A, and DNASE1L3). All genes harboring pathogenic variants were associated with interferon type-1 inflammatory response. Individuals harboring variants were more likely to have a preceding trigger (p = 0.03, 95% CI 1.21-97.06), rapid clinical decline in less than 1 month (p = 0.01, 95% CI 1.67-52.06), and MRI abnormalities (p < 0.001, 95% CI 4.89-527.71).

DISCUSSION

A distinct subset of individuals with DSRD exhibited pathogenic variants in immune regulation genes associated with interferon-mediated inflammatory response, coinciding with previously established links between these genes and interferonopathies such as Aicardi-Goutieres syndrome. Our observations suggest that these variants might potentially contribute to the development of DSRD in individuals with DS.

Safety and tolerability of intravenous immunoglobulin infusion in Down syndrome regression disorder

Three large multi-center studies have identified the clinical utility of intravenous immunoglobulin (IVIg) in the treatment of Down syndrome regression disorder (DSRD). Yet the tolerability of infusions in individuals with DS and the safety of IVIg remains unknown in this population. This study sought to evaluate the safety and tolerability of IVIg in individuals with DSRD compared to a real-world cohort of individuals with pediatric onset neuroimmunologic disorders. A single-center, retrospective chart review evaluating clinically documented infusion reactions was performed for individuals meeting international consensus criteria for DSRD and having IVIg infusions between 2019 and 2023. Infusion reactions were evaluated for severity and need for alterations in infusion plan. This cohort was compared against an age and sex matched cohort of children with neuroimmunologic conditions who had also received IVIg infusions. In total, 127 individuals with DSRD and 186 individuals with other neuroimmunologic disorders were enrolled. There was no difference in the overall rate of adverse reactions (AEs) between the DSRD and general neuroimmunology cohorts (p = 0.31, 95% CI: 0.80-2.00), but cardiac-related AEs specifically were more common among the DSRD group (p = 0.02, 95% CI: 1.23-17.54). When AEs did occur, there was no difference in frequency of pharmacologic intervention (p = 0.12, 95% CI: 0.34-1.13) or discontinuation of therapy (p = 0.74, 95% CI: 0.06-7.44). There was a higher incidence of lab abnormalities on IVIG among the general neuroimmunology cohort (p = 0.03, 95% CI: 0.24-0.94) compared to the DSRD cohort. Transaminitis was the most common laboratory abnormality in the DSRD group. In a large cohort of individuals with DSRD, there were no significant differences in the safety and tolerability of IVIg compared to a cohort of children and young adults with neuroimmunologic conditions.

Neuroimaging abnormalities associated with immunotherapy responsiveness in Down syndrome regression disorder

OBJECTIVE

To determine the prevalence of neuroimaging abnormalities in individuals with Down syndrome regression disorder (DSRD) and evaluate if neuroimaging abnormalities were predictive of therapeutic responses.

METHODS

A multicenter, retrospective, case-control study which reviewed neuroimaging studies of individuals with DSRD and compared them to a control cohort of individuals with Down syndrome (DS) alone was performed. Individuals aged 10-30 years and meeting international consensus criteria for DSRD were included. The presence of T1, T2/FLAIR, and SWI signal abnormalities was reviewed. Response rates to various therapies, including immunotherapy, were evaluated in the presence of neuroimaging abnormalities.

RESULTS

In total, 74 individuals (35%) had either T2/FLAIR and/or SWI signal abnormality compared to 14 individuals (12%) without DSRD (p < 0.001, 95%CI: 2.18-7.63). T2/FLAIR signal abnormalities were not appreciated more frequently in individuals with DSRD (14%, 30/210) than in the control cohort (9%, 11/119) (p = 0.18, OR: 1.63, 95%CI: 0.79-3.40). SWI signal abnormalities were appreciated at a higher frequency in individuals with DSRD (24%, 51/210) compared to the control cohort (4%, 5/119) (p < 0.001, OR: 7.31, 95%CI: 2.83-18.90). T2/FLAIR signal abnormalities were localized to the frontal (40%, 12/30) and parietal lobes (37%, 11/30). SWI signal abnormalities were predominantly in the bilateral basal ganglia (94%, 49/52). Individuals with DSRD and the presence of T2/FLAIR and/or SWI signal abnormalities were much more likely to respond to immunotherapy (p < 0.001, OR: 8.42. 95%CI: 3.78-18.76) and less likely to respond to benzodiazepines (p = 0.01, OR: 0.45, 95%CI: 0.25-0.83), antipsychotics (p < 0.001, OR: 0.28, 95%CI: 0.11-0.55), or electroconvulsive therapy (p < 0.001, OR: 0.12; 95%CI: 0.02-0.78) compared to individuals without these neuroimaging abnormalities.

INTERPRETATION

This study indicates that in individuals diagnosed with DSRD, T2/FLAIR, and SWI signal abnormalities are more common than previously thought and predict response to immunotherapy.

The Pediatric Integrated Care Survey (PICS) in a multidisciplinary clinic for Down syndrome

The Pediatric Integrated Care Survey (PICS) is validated for use to measure the caregiver reported experience of integration and efficiency of all the aspects of their child. We began using the PICS survey to track changes in the patient experience, including throughout changing models of care during the COVID-19 pandemic. From February 2019 to June 2023, 62 responses from caregivers of individuals seen in the Massachusetts General Hospital Down Syndrome Program completed the PICS. Responses were scored using the standardized PICS user manual, and descriptive statistics were completed. The raw scores and composite monthly scores of the PICs were graphed in statistical process control charts. The average PICS score was 12.0 (range 2-19) out of a maximum score of 19; no shifts or trends were seen. Items with lowest scores indicated greatest opportunities for improvement related to: advice from other care team members, impact of decisions on the whole family, things causing stress or making it hard because of child's health, and offering opportunities to connect with other families. Studying the PICS in a specialty clinic for Down syndrome for the first time has established a baseline for future quality improvement work and interventions to increase care integration.

Takotsubo cardiomyopathy secondary to electroconvulsive therapy in a young adult with Down syndrome regression disorder

We report the case of an 18-year-old woman with Down syndrome (DS) who developed Takotsubo cardiomyopathy (TSC) immediately after the administration of electroconvulsive therapy (ECT), a treatment prescribed for Down syndrome regression disorder resistant to oral psychotropic drugs. TSC is a nonischemic cardiomyopathy related to psychological or physical stress, which has been described as a rare complication of ECT (Kinoshita et al., 2023, Journal of Electroconvulsive Therapy, 39, 185-192). The clinical description of the case is accompanied by a discussion of the peculiarities of the autonomic nervous system in DS.

Transcranial Direct Current Stimulation in neurogenetic syndromes: new treatment perspectives for Down syndrome?

This perspective review aims to explore the potential neurobiological mechanisms involved in the application of transcranial Direct Current Stimulation (tDCS) for Down syndrome (DS), the leading cause of genetically-based intellectual disability. The neural mechanisms underlying tDCS interventions in genetic disorders, typically characterized by cognitive deficits, are grounded in the concept of brain plasticity. We initially present the neurobiological and functional effects elicited by tDCS applications in enhancing neuroplasticity and in regulating the excitatory/inhibitory balance, both associated with cognitive improvement in the general population. The review begins with evidence on tDCS applications in five neurogenetic disorders, including Rett, Prader-Willi, Phelan-McDermid, and Neurofibromatosis 1 syndromes, as well as DS. Available evidence supports tDCS as a potential intervention tool and underscores the importance of advancing neurobiological research into the mechanisms of tDCS action in these conditions. We then discuss the potential of tDCS as a promising non-invasive strategy to mitigate deficits in plasticity and promote fine-tuning of the excitatory/inhibitory balance in DS, exploring implications for cognitive treatment perspectives in this population.

Psychopharmacological treatments in Down syndrome and autism spectrum disorder: State of the research and practical considerations

Individuals with Down syndrome (DS) or Autism Spectrum Disorder (ASD), and especially those with both DS and co-occurring ASD (DS + ASD) commonly display behavioral and psychiatric symptoms that can impact quality of life and places increased burden on caregivers. While the mainstay of treatment in DS and ASD is focused on educational and behavioral therapies, pharmacological treatments can be used to reduce symptom burden. There is a paucity of evidence and limited clinical trials in DS and DS + ASD. Some scientific evidence is available, primarily in open label studies and case series that can guide treatment choices. Additionally, clinical decisions are often extrapolated from evidence and experience from those with ASD, or intellectual disability in those without DS. This article reviews current research in pharmacological treatment in DS, ASD, and DS + ASD, reviews co-occurring neurodevelopmental and mental health diagnoses in individuals with DS + ASD across the lifespan, and describes practical approaches to psychopharmacological management.

Children with Down syndrome who experience developmental skill loss, characterization, and phenomenology: A case series

Loss of previously acquired developmental skills in children with Down syndrome (DS) is not a well characterized phenomenon. We identified 20 confirmed cases of childhood-onset skill loss for descriptive analysis. Eligible participants were recruited from a specialty clinic for persons with DS at a large medical center. Age and gender-matched participants also with DS but without skill loss were used as a comparison group. Case and control participants were between 3 and 14 years (mean 7.6 yr) at the time of evaluation. Loss of previously acquired communication, social-communication, and play skills was experienced by all cases, as well as new-onset or intensification of pre-existing maladaptive behaviors. The Aberrant Behavior Checklist (ABC)-community was helpful in distinguishing group differences in maladaptive behavior among cases and controls. All cases met DSMIV criteria for autism. Developmental skill loss associated with autism is an extreme example of within-group phenotypic variability and needs to be the focus of further research.

Pneumonia vaccine response in individuals with Down syndrome at three specialty clinics

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.

Hypovitaminosis D in persons with Down syndrome and autism spectrum disorder

BACKGROUND

Plasma levels of vitamin D have been reported to be low in persons with Down syndrome (DS) and existing data is limited to small and homogenous cohorts. This is of particular importance in persons with DS given the high rates of autoimmune disease in this population and the known relationship between vitamin D and immune function. This study sought to investigate vitamin D status in a multi-center cohort of individuals with DS and compare them to individuals with autism spectrum disorder (ASD) and neurotypical (NT) controls.

METHODS

A retrospective, multi-center review was performed. The three sites were located at latitudes of 42.361145, 37.44466, and 34.05349. Patients were identified by the International Classification of Diseases (ICD)-9 or ICD-10 codes for DS, ASD, or well-child check visits for NT individuals. The first vitamin D 25-OH level recorded in the electronic medical record (EMR) was used in this study as it was felt to be the most reflective of a natural and non-supplemented state. Vitamin D 25-OH levels below 30 ng/mL were considered deficient.

RESULTS

In total, 1624 individuals with DS, 5208 with ASD, and 30,775 NT controls were identified. Individuals with DS had the lowest mean level of vitamin D 25-OH at 20.67 ng/mL, compared to those with ASD (23.48 ng/mL) and NT controls (29.20 ng/mL) (p < 0.001, 95% CI: -8.97 to -6.44). A total of 399 (24.6%) individuals with DS were considered vitamin D deficient compared to 1472 (28.3%) with ASD and 12,397 (40.3%) NT controls (p < 0.001, 95% CI: -5.43 to -2.36). Individuals with DS with higher body mass index (BMI) were found to be more likely to have lower levels of vitamin D (p < 0.001, 95% CI: -0.3849 to -0.1509). Additionally, having both DS and a neurologic diagnosis increased the likelihood of having lower vitamin D levels (p < 0.001, 95% CI: -5.02 to -1.28). Individuals with DS and autoimmune disease were much more likely to have lower vitamin D levels (p < 0.001, 95% CI: -6.22 to -1.55). Similarly, a history of autoimmunity in a first-degree relative also increased the likelihood of having lower levels of vitamin D in persons with DS (p = 0.01, 95% CI: -2.45 to -0.63).

CONCLUSIONS

Individuals with DS were noted to have hypovitaminosis D in comparison to individuals with ASD and NT controls. Associations between vitamin D deficiency and high BMI, personal autoimmunity, and familial autoimmunity were present in individuals with DS.

Immunotherapy responsiveness and risk of relapse in Down syndrome regression disorder

Down syndrome regression disorder (DSRD) is a clinical symptom cluster consisting of neuropsychiatric regression without an identifiable cause. This study evaluated the clinical effectiveness of IVIg and evaluated clinical characteristics associated with relapse after therapy discontinuation. A prospective, multi-center, non-randomized, observational study was performed. Patients met criteria for DSRD and were treated with IVIg. All patients underwent a standardized wean-off therapy after 9-12 months of treatment. Baseline, on-therapy, and relapse scores of the Neuropsychiatric Inventory Total Score (NPITS), Clinical Global Impression-Severity (CGI-S), and the Bush-Francis Catatonia Rating Scale (BFCRS) were used to track clinical symptoms. Eighty-two individuals were enrolled in this study. Patients had lower BFCRS (MD: -6.68; 95% CI: -8.23, -5.14), CGI-S (MD: -1.27; 95% CI: -1.73, -0.81), and NPITS scores (MD: -6.50; 95% CI: -7.53, -5.47) while they were on therapy compared to baseline. Approximately 46% of the patients (n = 38) experienced neurologic relapse with wean of IVIg. Patients with neurologic relapse were more likely to have any abnormal neurodiagnostic study (χ2 = 11.82, P = 0.001), abnormal MRI (χ2 = 7.78, P = 0.005), and abnormal LP (χ2 = 5.45, P = 0.02), and a personal history of autoimmunity (OR: 6.11, P < 0.001) compared to patients without relapse. IVIg was highly effective in the treatment of DSRD. Individuals with a history of personal autoimmunity or neurodiagnostic abnormalities were more likely to relapse following weaning of immunotherapy, indicating the potential for, a chronic autoimmune etiology in some cases of DSRD.

Down syndrome regression disorder: updates and therapeutic advances

PURPOSE OF REVIEW

Down syndrome regression disorder (DSRD) is a symptom cluster consisting of neuropsychiatric regression without cause. Although knowledge of this condition has accelerated over the last decade, prior studies have been limited by heterogenous nomenclature, diagnostic approaches and therapeutic interventions. This review highlights recent advances in the diagnosis and clinical approach to DSRD and reviews the most up-to-date literature on therapeutic interventions for this condition.

RECENT FINDINGS

Several multicentre studies have reported exciting findings on the presence of neurodiagnostic study abnormalities and responses to a variety of therapeutics, including psychotropics (including benzodiazepines), electroconvulsive therapy and immunotherapy. Differential response rates have been observed in the presence and absence of a variety of clinical and diagnostic factors.

SUMMARY

Individuals with DSRD are responsive to a variety of psychiatric pharmacotherapy and immunotherapy underscoring this phenotype may have multiple causes. Multidisciplinary care is helpful in the evaluation and management of individuals with this condition.

Immunotherapy Responsiveness and Risk of Relapse in Down Syndrome Regression Disorder

Down syndrome regression disorder (DSRD) is a clinical symptom cluster consisting of neuropsychiatric regression without an identifiable cause. This study evaluated the clinical effectiveness of IVIg and evaluated clinical characteristics associated with relapse after therapy discontinuation. A prospective, multi-center, non-randomized, observational study was performed. Patients met criteria for DSRD and were treated with IVIg. All patients underwent a standardized wean off therapy after 9-12 months of treatment. Baseline, on therapy, and relapse scores of the Neuropsychiatric Inventory Total Score (NPITS), Clinical Global Impression-Severity (CGI-S), and the Bush-Francis Catatonia Rating Scale (BFCRS) were used to track clinical symptoms. Eighty-two individuals were enrolled in this study. Patients had lower BFCRS (MD: -6.68; 95% CI: -8.23, -5.14), CGI-S (MD: -1.27; 95% CI: -1.73, -0.81), and NPITS scores (MD: -6.50; 95% CI: -7.53, -5.47) while they were on therapy compared to baseline. Approximately 46% of the patients (n = 38) experienced neurologic relapse with wean of IVIg. Patients with neurologic relapse were more likely to have any abnormal neurodiagnostic study (χ2 = 11.82, p = 0.001), abnormal MRI (χ2 = 7.78, p = 0.005), and abnormal LP (χ2 = 5.45, p = 0.02), and a personal history of autoimmunity (OR: 6.11, p < 0.001) compared to patients without relapse. IVIg was highly effective in the treatment of DSRD. Individuals with a history of personal autoimmunity or neurodiagnostic abnormalities were more likely to relapse following weaning of immunotherapy, indicating the potential for, a chronic autoimmune etiology in some cases of DSRD.

Down syndrome regression disorder, a case series: Clinical characterization and therapeutic approaches

Down syndrome (DS) is one of the most frequent genetic disorders and represents the first cause of intellectual disability of genetic origin. While the majority of patients with DS follow a harmonious evolution, an unusual neurodevelopmental regression may occur, distinct from that described in the context of autism spectrum disorders, called down syndrome regression disorder (DSRD). Based on four patients, two males and two females, with age range between 20 and 24, treated at the Reference Center for Rare Psychiatric Disorders of the GHU Paris Psychiatry and Neurosciences [Pôle hospitalo-universitaire d'Évaluation Prévention et Innovation Thérapeutique (PEPIT)], we describe this syndrome, discuss its etiologies and propose therapeutic strategies. DSRD often occurs in late adolescence. There is a sudden onset of language disorders, loss of autonomy and daily living skills, as well as behavioral symptoms such as depression, psychosis, or catatonia. These symptoms are non-specific and lead to an overlap with other diagnostic categories, thus complicating diagnosis. The etiologies of the syndrome are not clearly identified but certain predispositions of patients with trisomy 21 have suggested an underlying immune-mediated mechanism. Symptomatic therapeutic approaches (serotonergic antidepressants, atypical antipsychotics, benzodiazepines) were not effective, and generally associated with poor tolerance. Etiological treatments, including anti-inflammatory drugs and corticosteroids, led to partial or good recovery in the four cases. Early recognition of regressive symptoms and rapid implementation of adapted treatments are required to improve the quality of life of patients and their families.

Abnormal Brain Iron Accumulation is a Rare Finding in Down Syndrome Regression Disorder

BACKGROUND

Down syndrome regression disorder (DSRD) is characterized by the sudden loss of adaptive function, cognitive-executive function, and language with abnormal sleep and/or motor control.

METHODS

Clinical, laboratory, and imaging data from three individuals with DSRD and iron on brain imaging were reviewed.

RESULTS

Three patients with Down syndrome presented with new onset of flat affect, depression, reduced speech, and other neurological symptoms consistent with DSRD. Magnetic resonance imaging showed abnormal iron accumulation in the basal ganglia, as well as calcification in two cases. Molecular diagnostic testing for neurodegeneration with brain iron accumulation was negative in the two individuals tested.

CONCLUSIONS

These individuals presented suggest that a subset of individuals with DSRD have abnormal brain iron accumulation. Motor control symptoms reported in DSRD, such as stereotypies and parkinsonism, may reflect this basal ganglia involvement. The presence of abnormal brain iron should not delay or preclude diagnosis and treatment for DSRD.

Unexplained regression in Down syndrome: Management of 51 patients in an international patient database

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.

Is Developmental Regression in Down Syndrome Linked to Life Stressors?

OBJECTIVE

Unexplained regression in Down syndrome (URDS) involves a loss of acquired skills resulting in functional deterioration. Despite extensive workup and treatment, few individuals regain baseline function. This study aimed to understand the role of psychosocial stressors in URDS.

METHODS

We describe psychosocial stressors in 14 cases of URDS. Specifically, we examined psychosocial stressors in the context of presentation and clinical symptoms. We also examined co-occurring neurodevelopmental disorders and medical and mental health conditions.

RESULTS

All individuals experienced psychosocial stressors within one year of diagnosis of URDS. The most common psychosocial stressors were moving to a new home or school.

CONCLUSION

Psychosocial stressors are commonly reported preceding URDS. Knowledge about psychosocial stressors' impact may lead to preventive interventions, improved monitoring, and earlier diagnosis. Future research should focus on understanding psychosocial stressors to help identify individuals at risk for URDS and contribute to treatment.

Assessment and Diagnosis of Down Syndrome Regression Disorder: International Expert Consensus

Objective

To develop standardization for nomenclature, diagnostic work up and diagnostic criteria for cases of neurocognitive regression in Down syndrome.

Background

There are no consensus criteria for the evaluation or diagnosis of neurocognitive regression in persons with Down syndrome. As such, previously published data on this condition is relegated to smaller case series with heterogenous data sets. Lack of standardized assessment tools has slowed research in this clinical area.

Methods

The authors performed a two-round traditional Delphi method survey of an international group of clinicians with experience in treating Down syndrome to develop a standardized approach to clinical care and research in this area. Thirty-eight potential panelists who had either previously published on neurocognitive regression in Down syndrome or were involved in national or international working groups on this condition were invited to participate. In total, 27 panelists (71%) represented nine medical specialties and six different countries reached agreement on preliminary standards in this disease area. Moderators developed a proposed nomenclature, diagnostic work up and diagnostic criteria based on previously published reports of regression in persons with Down syndrome.

Results

During the first round of survey, agreement on nomenclature for the condition was reached with 78% of panelists agreeing to use the term Down Syndrome Regression Disorder (DSRD). Agreement on diagnostic work up and diagnostic criteria was not reach on the first round due to low agreement amongst panelists with regards to the need for neurodiagnostic testing. Following incorporation of panelist feedback, diagnostic criteria were agreed upon (96% agreement on neuroimaging, 100% agreement on bloodwork, 88% agreement on lumbar puncture, 100% agreement on urine studies, and 96% agreement on "other" studies) as were diagnostic criteria (96% agreement).

Conclusions

The authors present international consensus agreement on the nomenclature, diagnostic work up, and diagnostic criteria for DSRD, providing an initial practical framework that can advance both research and clinical practices for this condition.

Abnormal Weight Loss in an Adolescent Female With Down Syndrome

Down syndrome is the most common chromosomal abnormality identified at birth. These individuals will have multiple comorbid illnesses that require complex medical care throughout their lives. In recent years, specific patterns of regression have been detected in these individuals; most notably, developmental regression with language, behavior, and cognitive skills that they had previously acquired, which now affects both the quality of life and autonomy. These development regression patterns are referred to as Down syndrome disintegrative disorder.

The case that we are reporting occurred in a 17-year-old female presenting with significant weight loss, altered mental status, and loss of functional skills over a period of one month. Co-occurring hypothyroidism and hyperthyroidism symptoms exacerbation may have triggered this patient’s regression. Our case highlights the importance of conducting a thorough investigation for life-threatening and non-life-threatening illnesses that can present with similar symptoms, in order to make the correct diagnosis of Down syndrome disintegrative disorder and find appropriate therapies and future care.

Evidence of neuroinflammation and immunotherapy responsiveness in individuals with down syndrome regression disorder

Background

Down syndrome regression disorder is a symptom cluster consisting of neuropsychiatric regression without cause. This study evaluated the incidence of neurodiagnostic abnormalities in individuals with Down syndrome regression disorder and determined if abnormalities are indicative of responses to therapeutic intervention.

Methods

A retrospective, multi-center, case-control study was performed. Patients were required to have subacute onset and the presence of four of five symptom groups present (cognitive decline, expressive language, sleep derangement, loss of ability to perform activities of daily living, and/or a new movement disorder) and no other explanation for symptoms.

Results

Individuals with Down syndrome regression disorder were comparable to a cohort of individuals with only Down syndrome although had higher rates of autoimmune disease (p = 0.02, 95%CI 1.04–1.75). Neurodiagnostic abnormalities were found on EEG (n = 19, 26%), neuroimaging (n = 16, 22%), and CSF (n = 9, 17%). Pleocytosis was appreciated in five cases, elevated total protein in nine, elevated IgG index in seven, and oligoclonal bands in two. Testing within 2 years of symptom onset was more likely to have neurodiagnostic abnormalities (p = 0.01, 95%CI 1.64–37.06). In individuals with neurodiagnostic abnormalities, immunotherapy was nearly four times more likely to have a therapeutic effect than in those without neurodiagnostic abnormalities (OR 4.11, 95%CI 1.88–9.02). In those with normal neurodiagnostic studies (n = 43), IVIg was effective in 14 of 17 (82%) patients as well although other immunotherapies were uniformly ineffective.

Conclusions

This study reports the novel presence of neurodiagnostic testing abnormalities in individuals with Down syndrome regression disorder, providing credence to this symptom cluster potentially being of neurologic and/or neuroimmunologic etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11689-022-09446-w.

[Regression in Young Adults with Down-Syndrome: A Case Series]

BACKGROUND

Regression in young adults with Down syndrome can present itself with an acute loss of acquired skills and change in behavior. The aim of our case series was to describe the heterogeneous clinical presentation of this syndrome as well as accompanying diagnostic and therapeutic challenges and consequences.

METHODS

All three patients were assessed with the CAMDEX-DS (Cambridge Examination for Mental Disorders of Older People with Down Syndrome and Others with Intellectual Disabilities) and the criteria published by the DSMIG-USA (Down-Syndrome Medical Interest Group USA).

RESULTS

After ruling out somatic or other psychiatric causes, the application of the DSMIG-USA criteria resulted in diagnosing at least a probable unexplained regression in all three patients.

DISCUSSION

The thorough diagnostic investigation of unexplained acute regression in young adults with Down syndrome allows for quick initiation of therapeutic and supportive measures. Using the DMSIG-USA criteria facilitates the assessment of the underlying diffuse and heterogenous pathology.

Prenatal and Postnatal Pharmacotherapy in Down Syndrome: The Search to Prevent or Ameliorate Neurodevelopmental and Neurodegenerative Disorders

Those with Down syndrome (DS)-trisomy for chromosome 21-are routinely impacted by cognitive dysfunction and behavioral challenges in children and adults and Alzheimer's disease in older adults. No proven treatments specifically address these cognitive or behavioral changes. However, advances in the establishment of rodent models and human cell models promise to support development of such treatments. A research agenda that emphasizes the identification of overexpressed genes that contribute demonstrably to abnormalities in cognition and behavior in model systems constitutes a rational next step. Normalizing expression of such genes may usher in an era of successful treatments applicable across the life span for those with DS.

A Systematic Review of Unexplained Early Regression in Adolescents and Adults with Down Syndrome

A proportion of young people with Down syndrome (DS) experience unexplained regression that severely impacts on their daily lives. While this condition has been recognised by clinicians, there is a limited understanding of causation and an inconsistent approach to diagnosis and treatment. Varied symptomology and little knowledge of the cause of this regression have impacted on clinician's ability to prevent or manage this condition. The purpose of this review was to examine the current evidence surrounding unexplained regression in adolescents and young adults, and to establish patterns that may be of use to clinicians, as well as raising awareness of this condition. Four areas were specifically reviewed, (1) terminology used to refer to this condition, (2) the symptoms reported, (3) potential trigger events and, (4) treatments and prognosis. A variety of terminology is used for this condition, which has constrained past attempts to identify patterns. An extensive number of symptoms were reported, however sleep impairment, loss of language and distinct changes in personality and behaviour, such as disinterest and withdrawal, were among the most frequently seen. Life events that were tentatively associated with the onset of a regressive period included a significant change in environmental circumstances or a transition, such as moving home or leaving school. Prognosis for this condition is relatively positive with the majority of individuals making at least a partial recovery. However, few patients were found to make a full recovery to their previous level of functioning and serious adverse effects could persist in those who have made a partial recovery. This is an under-researched condition with significant impacts on people with DS and their families. There are no established treatments for this condition and there is relatively little recognition in the research community. Further studies that focus on the prevention and treatment of this condition with controlled treatment trials are needed.

Acute Regression in Down Syndrome

BACKGROUND

Acute regression has been reported in some individuals with Down syndrome (DS), typically occurring between the teenage years and mid to late 20s. Characterized by sudden, and often unexplained, reductions in language skills, functional living skills and reduced psychomotor activity, some individuals have been incorrectly diagnosed with Alzheimer's disease (AD).

METHODS

This paper compares five individuals with DS who previously experienced acute regression with a matched group of 15 unaffected individuals with DS using a set of AD biomarkers.

RESULTS

While the sample was too small to conduct statistical analyses, findings suggest there are possible meaningful differences between the groups on proteomics biomarkers (e.g., NfL, total tau). Hippocampal, caudate and putamen volumes were slightly larger in the regression group, the opposite of what was hypothesized. A slightly lower amyloid load was found on the PET scans for the regression group, but no differences were noted on tau PET.

CONCLUSIONS

Some proteomics biomarker findings suggest that individuals with DS who experience acute regression may be at increased risk for AD at an earlier age in comparison to unaffected adults with DS. However, due to the age of the group (mean 38 years), it may be too early to observe meaningful group differences on image-based biomarkers.

Case Report: Improvement Following Immunotherapy in an Individual With Seronegative Down Syndrome Disintegrative Disorder

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.