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Down Syndrome Regression Disorder (DRSD) is an uncommon but devastating condition affecting primarily adolescents and young adults with Down syndrome (DS). Individuals with DS display a dysregulated immune system associated with hyperactive interferon signaling, which is associated with a high incidence of autoimmune conditions. While the cause of DSRD is unknown, increasing evidence indicates that it may have an immune basis, and some individuals with DSRD have responded to intravenous immunoglobulin therapy. This case series describes three individuals with probable DSRD who received the JAK inhibitor tofacitinib and saw improvement in DSRD symptoms across multiple domains of neurological function., Competing Interests: Declaration of competing interest J.M.E. has provided consulting services for Elli Lily and Co., Gilead Sciences Inc., Biohaven Pharmaceuticals, and Perha Pharmaceuticals., (Copyright © 2024. Published by Elsevier B.V.)

A 14-year-old boy with Down syndrome (DS) showed a gradual decline in his daily activities and feeding capacities, and a marked deterioration triggered by a streptococcal infection was observed at the age of 15 years. He became bedridden, accompanied by sleep disturbance, sustained upward gaze, and generalized rigidity. Magnetic resonance imaging showed unremarkable findings, but antiglutamate receptor autoantibodies were positive in his cerebrospinal fluid. Treatment with thiamine infusion and steroid pulse therapy showed little effect, but gross motor dysfunction and appetite loss were ameliorated by the administration of l-DOPA and serotonin reuptake inhibitors. Thereafter, autistic behaviors predominated, including loss of social interaction, oral tendency, water phobia, and aggressiveness. Initiation of donepezil, an acetylcholinesterase inhibitor, resulted in the disappearance of these symptoms and total recovery of the patient to his previous psychosocial levels. We hypothesize that the acute regression in adolescence represents a process closely related to the defects of serotonergic and cholinergic systems that are innate to DS brains and not just a nonspecific comorbidity of depression or limbic encephalitis., (Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Genetic alterations or pharmacological treatments affecting endocannabinoid signaling have profound effects on synaptic and neuronal properties and, under certain conditions, may improve higher brain functions. Down syndrome (DS), a developmental disorder caused by triplication of chromosome 21, is characterized by deficient cognition and inevitable development of the Alzheimer disease (AD) type pathology during aging. Here we used JZL184, a selective inhibitor of monoacylglycerol lipase (MAGL), to examine the effects of chronic MAGL inhibition on the behavioral, biochemical, and synaptic properties of aged Ts65Dn mice, a genetic model of DS. In both Ts65Dn mice and their normosomic (2N) controls, JZL184-treatment increased brain levels of 2-arachidonoylglycerol (2-AG) and decreased levels of its metabolites such as arachidonic acid, prostaglandins PGD2, PGE2, PGFα, and PGJ2. Enhanced spontaneous locomotor activity of Ts65Dn mice was reduced by the JZL184-treatement to the levels observed in 2N animals. Deficient long-term memory was also improved, while short-term and working types of memory were unaffected. Furthermore, reduced hippocampal long-term potentiation (LTP) was increased in the JZL184-treated Ts65Dn mice to the levels observed in 2N mice. Interestingly, changes in synaptic plasticity and behavior were not observed in the JZL184-treated 2N mice suggesting that the treatment specifically attenuated the defects in the trisomic animals. The JZL184-treatment also reduced the levels of Aβ40 and Aβ42, but had no effect on the levels of full length APP and BACE1 in both Ts65Dn and 2N mice. These data show that chronic MAGL inhibition improves the behavior and brain functions in a DS model suggesting that pharmacological targeting of MAGL may be considered as a perspective new approach for improving cognition in DS.

Although antagonists to GluN2B-containing N-methyl-D-aspartate receptors (NMDARs) have been widely considered to be neuroprotective under certain pathological conditions, their immediate and lasting impacts on synaptic, circuit, and cognitive functions are poorly understood. In hippocampal slices, we found that the GluN2B-selective antagonist Ro25-6981 (Ro25) reduced synaptic NMDAR responses and consequently neuronal output in a subpopulation of GABAergic interneurons, but not pyramidal neurons. Consistent with these effects, Ro25 reduced GABAergic responses in pyramidal neurons and hence could affect circuit functions by altering the excitation/inhibition balance in the brain. In slices from Ts65Dn mice, a Down syndrome model with excess inhibition and cognitive impairment, acutely applied Ro25-rescued long-term potentiation (LTP) and gamma oscillation deficits, whereas prolonged dosing induced persistent rescue of LTP. In contrast, Ro25 did not impact LTP in wild-type (wt) mice but reduced gamma oscillations both acutely and following prolonged treatment. Although acute Ro25 treatment impaired memory performance in wt mice, memory deficits in Ts65Dn mice were unchanged. Thus, GluN2B-NMDARs contribute to the excitation/inhibition balance via impacts on interneurons, and blocking GluN2B-NMDARs can alter functions that depend on this balance, including synaptic plasticity, gamma oscillations, and memory. That prolonged GluN2B antagonism leads to persistent changes in synaptic and circuit functions, and that the influence of GluN2B antagonism differs between wt and disease model mice, provide critical insight into the therapeutic potential and possible liabilities of GluN2B antagonists.

Objective: Down syndrome (DS) patients share certain neuropathological features with Alzheimer disease patients. A randomized, double-blind, placebo-controlled study was performed to investigate the efficacy and safety of donepezil, an Alzheimer disease drug, for DS patients., Method: Twenty-one DS patients with severe cognitive impairment were assigned to take donepezil (3 mg daily) or a placebo for 24 weeks, and evaluated for activities in daily lives by concisely modified International Classification of Functioning, Disability and Health (ICF) scaling system., Results: ICF scores significantly increased without any adverse effects in the donepezil group in comparison to those in the placebo control. Among the individual functions tested, there was a dramatic improvement in the global mental functions and in specific mental functions., Conclusions: Donepezil may effectively and safely improve overall functioning of DS patients with severe cognitive impairment.

The objective of this 10-week, randomized, double-blind, placebo-controlled multicenter study was to assess the efficacy and safety of donepezil for the treatment of cognitive dysfunction exhibited by children with Down syndrome (DS). Intervention comprised donepezil (2.5-10 mg/day) in children (aged 10-17 years) with DS of mild-to-moderate severity. The primary measures were the Vineland-II Adaptive Behavior Scales (VABS-II) Parent/Caregiver Rating Form (PCRF) the sum of nine subdomain standardized scores and standard safety measures. Secondary measures included the VABS-II/PCRF scores on the following domains and their respective individual subdomains: Communication (receptive, expressive, and written); Daily Living Skills (personal, domestic, and community); Socialization (interpersonal relationships, play and leisure time, and coping skills), and scores on the Test of Verbal Expression and Reasoning, a subject-performance-based measure of expressive language. At baseline, 129 participants were assigned treatment with donepezil or placebo. During the double-blind phase, VABS II/PCRF sum of the nine subdomain standardized scores, called v-scores, improved significantly from baseline in both groups (P < 0.0001), with no significant between-group differences. This trial failed to demonstrate any benefit for donepezil versus placebo in children and adolescents with DS, although donepezil appeared to be well tolerated., (© 2010 Wiley-Liss, Inc.)

The objective of our study was to assess the efficacy and safety of donepezil in young adults with Down syndrome (DS) but no evidence of Alzheimer disease (AD). A 12-week, randomized, double-blind, placebo-controlled study with a 12-week, open-label extension was conducted. The intervention consisted of donepezil (5-10 mg/day) in young adults (aged 18-35 years) with DS, but no AD. The primary measure was the Severe Impairment Battery (SIB) test and secondary measures were the Vineland Adaptive Behavior Scales (VABS), the Rivermead Behavioral Memory Test for Children, and the Clinical Evaluation of Language Fundamentals, Third Edition. At baseline, 123 subjects were randomly assigned treatment with donepezil or placebo. During the double-blind phase, SIB scores improved significantly from baseline in both groups, with no significant between-group differences. During the open-label phase, SIB scores in the original donepezil group remained stable; the original placebo group showed an improvement similar to that seen in the double-blind phase. VABS scores improved for donepezil, but not placebo, during the double-blind phase (observed cases, P = 0.03; last observation carried forward, P = 0.07). Post hoc responder analyses were significant for donepezil using three of five response definitions (P < or = 0.045). Adverse event rates were comparable to AD studies. In this first large-scale, multicenter trial of a pharmacological agent for DS, donepezil appears safe. Efficacy interpretation was limited for the primary measure due to apparent learning/practice and ceiling effects. Outcomes in post hoc analyses suggested efficacy in some, but not all subjects, consistent with phenotypic variability of DS. Additional studies are required to confirm potential benefits of donepezil in this population., (2009 Wiley-Liss, Inc.)

This review discusses the laboratory and clinical research supporting the rationale for the efficacy of donepezil (Aricept USA) in enhancing cognition in autism, Alzheimer disease, Down syndrome, traumatic brain injury, Attention Deficit Hyperactivity Disorder (ADHD), and schizophrenia. While preliminary animal models have shown effective, human studies exclusive of Alzheimer disease are sparse. Although attention and memory are unlikely a sole operation of the cholinergic system, evidence indicates a promising direction for further examination of this hypothesis in autism. Studies that examine changes in operationally defined behaviors and reliable and valid measure of changes in attention and memory are needed.

There is growing evidence to support the use of early central cholinergic enhancement to improve cognitive functioning in individuals with Down syndrome (DS). This report summarizes preliminary safety and cognitive efficacy data for seven children (8-13 years) with DS who participated in a 22-week, open-label trial of donepezil hydrochloride. Donepezil was dosed once daily at 2.5 mg and, based on tolerability, increased to 5 mg/day. Safety assessments were conducted at Week 1 (baseline), Week 8 (2.5 mg donepezil), Week 16 (5 mg) and Week 22 (after the donepezil had been discontinued). Measures of cognitive function were administered at each visit, encompassing the following domains: memory; attention; mood; and adaptive functioning. Donepezil was well tolerated at the 2.5 and 5 mg doses. The side effects were mild, transient, and consistent with the adverse events noted with cholinesterase inhibitors. Some children showed improvement on measures of memory (NEPSY Memory for Names and Narrative Memory) and sustained attention to tasks (Conners' Parent Rating Scales), although increased irritability and/or assertiveness were noted in some patients. Overall, this clinical report series adds to our initial findings of language gains in children with DS treated with donepezil. It also supports the need for larger, double-blind studies of the safety and efficacy of donepezil and other cholinesterase inhibitors for children with DS., ((c) 2007 Wiley-Liss, Inc.)

Our goal in this study was to determine whether donepezil, an acetylcholinesterase inhibitor, would improve cognitive functioning in 19 subjects with Down syndrome and no dementia. They were assigned to either a donepezil or placebo group. Cognitive functioning and caregiver ratings were measured at baseline, 4 weeks, and 12 weeks. With the exception of one area (language), no improvement was noted in any of the cognitive subtests, behavioral scores, or caregiver ratings. Subjects in the donepezil group showed an improvement in language scores compared to subjects in the placebo group. The results suggest that donepezil may improve language performance in subjects with Down syndrome and no dementia, but further studies need to be done on a larger group to confirm this result.

Background: Individuals with Down syndrome who develop Alzheimer disease may show an improvement in cognitive functioning after treatment with acetylcholinesterase inhibitors., Objective: To determine whether individuals with Down syndrome and Alzheimer disease will show improvement after institution of donepezil treatment., Design: A nonrandomized controlled trial using donepezil in a pilot study format., Setting: Academic medical center., Patients: Convenience sample of 6 treated patients with Down syndrome and 9 closely matched historical control subjects., Intervention: Oral administration of donepezil for a 5-month period., Primary Outcome Measure: The Down Syndrome Dementia Scale., Results: Significant improvement in dementia scores for the treated group during a 3- to 5-month period (P =.03)., Conclusions: Acetylcholinesterase inhibitors may be helpful in reversing the symptoms of dementia during early and middle stages of cognitive decline. These findings support the rationale for a more extensive study of the efficacy of acetylcholinesterase inhibitors in Down syndrome dementia.

Background: Donepezil Hydrochloride (Aricept) is a selective anticholinesterase inhibitor developed for the treatment of Alzheimer's disease (AD). This study investigated the safety and efficacy of the drug to treat Down syndrome (DS) adults with mild to moderate AD., Method: This was a 24-week, double blind, placebo controlled, parallel-group trial. Patients were randomized to receive placebo or donepezil (5 mg per day during the first four weeks, and then 10 mg per day thereafter). Primary efficacy was measured using the Dementia Scale for Mentally Retarded Persons (DMR), and secondary efficacy was measured using the Severe Impairment Battery (SIB), Neuropsychiatric Inventory (NPI) and by the Adaptive Behavior Scale (ABS)., Results: A total of 30 DS patients with AD entered the study of which 27 were included in the subsequent data analysis. The donepezil group had non-statistically significant reduction in deterioration in DMR, SIB, and ABS mean scores relative to the placebo group. However NPI scores showed less improvement in the donepezil group when compared to the placebo group. Fifty percent of subjects in the donepezil group showed improvement in mean DMR scores at the end point compared to baseline, when compared to 31% on placebo. There were no life threatening adverse effects associated with treating adults with DS with donepezil. A number of side-effects did occur including diarrhoea, insomnia, fatigue, and nausea., Conclusion: Donepezil Hydrochloride administered once a day appears to be generally well tolerated and safe in DS adults who have AD. There is some possible efficacy in the treatment of symptoms of mild to moderate Alzheimer's disease in this population, although the sample size of this study was too small for statistical significance. It is recommended that donepezil, with the appropriate precautions, should be considered for the treatment of AD in adults with DS as deemed by a specialist., (Copyright 2002 John Wiley & Sons, Ltd.)