Down Syndrome Language Research Papers (original) (raw)

Locus coeruleus (LC) neurons in the brainstem send extensive noradrenergic (NE)-ergic terminals to the majority of brain regions, particularly those involved in cognitive function. Both Alzheimer’s disease (AD) and Down syndrome (DS) are characterized by similar pathology including significant LC degeneration and dysfunction of the NE-ergic system. Extensive loss of NE-ergic terminals has been linked to alterations in brain regions vital for cognition, mood, and executive function. While the mechanisms by which NE-ergic abnormalities contribute to cognitive dysfunction are not fully understood, emergent evidence suggests that rescue of NE-ergic system can attenuate neuropathology and cognitive decline in both AD and DS. Therapeutic strategies to enhance NE neurotransmission have undergone limited testing. Among those deployed to date are NE reuptake inhibitors, presynaptic α-adrenergic receptor antagonists, NE prodrugs, and β-adrenergic agonists. Here we examine alterations in the NE-ergic system in AD and DS and suggest that NE-ergic system rescue is a plausible treatment strategy for targeting cognitive decline in both disorders.

- by
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- Dementia, Alzheimer's Disease, Alzheimer and Language, Down Syndrome Language

Chromosome 21, triplicated in Down Syndrome, contains several genes that are thought to play a critical role in the development of AD neuropathology. The overexpression of the gene for the amyloid precursor protein (APP), on chromosome 21, leads to early onset beta-amyloid (Aβ) plaques in DS. In addition to Aβ accumulation, middle-aged people with DS develop neurofibrillary tangles, cerebrovascular pathology, white matter pathology, oxidative damage, neuroinflammation and neuron loss. There is also evidence of potential compensatory responses in DS that benefit the brain and delay the onset of dementia after there is sufficient neuropathology for a diagnosis of AD. This review describes some of the existing literature and also highlights gaps in our knowledge regarding AD neuropathology in DS. It will be critical in the future to develop networked brain banks with standardized collection procedures to fully characterize the regional and temporal pathological events associated with aging in DS. As more information is acquired regarding AD evolution in DS, there will be opportunities to develop interventions that are age-appropriate to delay AD in DS.

- by Bentham Science Publishers
- •
- Pathology, Mirror Neurons, Alzheimer's Disease, Down Syndrome Language

Locus coeruleus (LC) neurons in the brainstem send extensive noradrenergic (NE)-ergic terminals to the majority of brain regions, particularly those involved in cognitive function. Both Alz-heimer's disease (AD) and Down syndrome (DS) are characterized by similar pathology including significant LC degeneration and dysfunction of the NE-ergic system. Extensive loss of NE-ergic terminals has been linked to alterations in brain regions vital for cognition, mood, and executive function. While the mechanisms by which NE-ergic abnormalities contribute to cognitive dysfunction are not fully understood, emergent evidence suggests that rescue of NE-ergic system can attenuate neuropathology and cogni-tive decline in both AD and DS. Therapeutic strategies to enhance NE neurotransmission have undergone limited testing. Among those deployed to date are NE reuptake inhibitors, presynaptic α-adrenergic receptor antagonists, NE prodrugs, and β-adrenergic agonists. Here we examine alterations in the NE-ergic system in AD and DS and suggest that NE-ergic system rescue is a plausible treatment strategy for targeting cognitive decline in both disorders.

Down syndrome is an intellectual disability requiring periodic monitoring of cognition given the near universal presence of Alzheimer’s Disease related neuropathology and high rates of dementia in middle adulthood. We review current approaches to detecting decline in this population, including informant-based measures, dementia screening tools, and neuroimaging techniques. The challenges for detecting decline in this group are discussed, including the need to take into account premorbid cognitive function as well as medical comorbidity.

Down syndrome (DS) is the most common non-lethal genetic condition that affects approximately 1 in 700 births in the United States of America. DS is characterized by complete or segmental chromosome 21 trisomy, which leads to variable intellectual disabilities, progressive memory loss, and accelerated neurodegeneration with age. During the last three decades, people with DS have experienced a doubling of life expectancy due to progress in treatment of medical comorbidities, which has allowed this population to reach the age when they develop early onset Alzheimer's disease (AD). Individuals with DS develop cognitive and pathological hallmarks of AD in their fourth or fifth decade, and are currently lacking successful prevention or treatment options for dementia. The profound memory deficits associated with DS-related AD (DS-AD) have been associated with degeneration of several neuronal populations, but mechanisms of neurodegeneration are largely unexplored. The most successful animal model for DS is the Ts65Dn mouse, but several new models have also been developed. In the current review, we discuss recent findings and potential treatment options for the management of memory loss and AD neuropathology in DS mouse models. We also review age-related neuropathology, and recent findings from neuroimaging studies. The validation of appropriate DS mouse models that mimic neurodegeneration and memory loss in humans with DS can be valuable in the study of novel preventative and treatment interventions, and may be helpful in pinpointing gene-gene interactions as well as specific gene segments involved in neurodegeneration.

It is well established that individuals with Down syndrome develop Alzheimer's disease neuropathology by middle age. Both in Alzheimer's disease and Down syndrome, this is accompanied by the atrophy of NGF-dependent cholinergic neurons of the basal forebrain. An NGF trophic compromise in Alzheimer's disease had been early suspected. This hypothesis was discarded with the finding of unaltered NGF mRNA synthesis and of increased NGF precursor levels (proNGF) in post-mortem Alzheimer's disease brains. The possibility of an NGF trophic disconnection has been recently revisited at the light of a newly discovered extracellular NGF metabolic pathway; where proNGF is released in an activity-dependent manner and converted by plasmin to mature NGF in the extracellular space. Mature NGF is ultimately degraded by the metalloprotease MMP-9. This pathway has been shown to be compromised in Alzheimer's disease and Down syndrome brains, thus reviving the trophic factor hypothesis to explain the atrophy of basal forebrain cholinergic neurons in these disorders. This chapter will discuss the physiological role of NGF and its biological significance to cho-linergic neurons of the CNS, and present the evidence for a dysregulation of the NGF metabolism in Alzheimer's disease and Down syndrome.

Chromosome 21, triplicated in Down Syndrome, contains several genes that are thought to play a critical role in the development of AD neuropathology. The overexpression of the gene for the amyloid precursor protein (APP), on chromosome 21, leads to early onset beta-amyloid (Aβ) plaques in DS. In addition to Aβ accumulation, middle-aged people with DS develop neurofibrillary tangles, cerebrovascular pathology , white matter pathology, oxidative damage, neuroinflammation and neuron loss. There is also evidence of potential compensatory responses in DS that benefit the brain and delay the onset of dementia after there is sufficient neuropa-thology for a diagnosis of AD. This review describes some of the existing literature and also highlights gaps in our knowledge regarding AD neuropathology in DS. It will be critical in the future to develop networked brain banks with standardized collection procedures to fully characterize the regional and temporal pathological events associated with aging in DS. As more information is acquired regarding AD evolution in DS, there will be opportunities to develop interventions that are age-appropriate to delay AD in DS.

- by Maria de Fatima de Almeida Baia and +1
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- Down Syndrome Language, Language Acquisition and Development, Down Syndrome

Down syndrome (DS), caused by trisomy of chromosome 21, is marked by intellectual disability (ID) and early onset of Alzheimer's disease (AD) neuropathology including hippocampal cho-linergic projection system degeneration. Here we determined the effects of age and maternal choline supplementation (MCS) on hippocampal cholinergic deficits in Ts65Dn mice compared to 2N mice sacrificed at 6-8 and 14-18 months of age. Ts65Dn mice and disomic (2N) littermates sacrificed at ages 6-8 and 14-18 mos were used for an aging study and Ts65Dn and 2N mice derived from Ts65Dn dams were maintained on either a choline-supplemented or a choline-controlled diet (conception to weaning) and examined at 14-18 mos for MCS studies. In the latter, mice were be-haviorally tested on the radial arm Morris water maze (RAWM) and hippocampal tissue was examined for intensity of choline acetyltransferase (ChAT) immunoreactivity. Hippocampal ChAT activity was evaluated in a separate cohort. ChAT-positive fiber innervation was significantly higher in the hippocampus and dentate gyrus in Ts65Dn mice compared with 2N mice, independent of age or maternal diet. Similarly, hippocampal ChAT activity was significantly elevated in Ts65Dn mice compared to 2N mice, independent of maternal diet. A significant increase with age was seen in hippocam-pal cholinergic innervation of 2N mice, but not Ts65Dn mice. Degree of ChAT intensity correlated negatively with spatial memory ability in unsupplemented 2N and Ts65Dn mice, but positively in MCS 2N mice. The increased innervation produced by MCS appears to improve hippocampal function, making this a therapy that may be exploited for future transla-tional approaches in human DS.

- by Bentham Science Publishers
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- Alzheimer's Disease, Spatial Memory, Down Syndrome Language, Aging

Trisomy 21 and the consequent extra copy of the amyloid precursor protein (APP) gene and increased beta-amyloid (Aβ) peptide production underlie the universal development of Alzheimer's disease (AD) pathology and high risk of AD dementia in people with Down syndrome (DS). Trisomy 21 and other forms of aneuploidy also arise among neurons and peripheral cells in both sporadic and familial AD and in mouse and cell models thereof, reinforcing the conclusion that AD and DS are two sides of the same coin. The demonstration that 90% of the neurodegeneration in AD can be attributed to the selective loss of aneuploid neurons generated over the course of the disease indicates that aneuploidy is an essential feature of the pathogenic pathway leading to the depletion of neuronal cell populations. Trisomy 21 mosaicism also occurs in neurons and other cells from patients with Niemann-Pick C1 disease and from patients with familial or sporadic frontotemporal lobar degeneration (FTLD), as well as in their corresponding mouse and cell models. Biochemical studies have shown that Aβ induces mitotic spindle defects, chromosome mis-segregation, and aneuploidy in cultured cells by inhibiting specific microtubule motors required for mitosis. These data indicate that neuronal trisomy 21 and other types of aneuploidy characterize and likely contribute to multiple neurodegenerative diseases and are a valid target for therapeutic intervention. For example, reducing extracellular calcium or treating cells with lithium chloride (LiCl) blocks the induction of trisomy 21 by Aβ. The latter finding is relevant in light of recent reports of a lowered risk of dementia in bipolar patients treated with LiCl and in the stabilization of cognition in AD patients treated with LiCl.

Down syndrome (DS) is the most common non-lethal genetic condition that affects approximately 1 in 700 births in the United States of America. DS is characterized by complete or segmental chromosome 21 trisomy, which leads to variable intellectual disabilities, progressive memory loss, and accelerated neurodegeneration with age. During the last three decades, people with DS have experienced a doubling of life expectancy due to progress in treatment of medical comorbidities, which has allowed this population to reach the age when they develop early onset Alzheimer’s disease (AD). Individuals with DS develop cognitive and pathological hallmarks of AD in their fourth or fifth decade, and are currently lacking successful prevention or treatment options for dementia. The profound memory deficits associated with DS-related AD (DS-AD) have been associated with degeneration of several neuronal populations, but mechanisms of neurodegeneration are largely unexplored. The most successful animal model for DS is the Ts65Dn mouse, but several new models have also been developed. In the current review, we discuss recent findings and potential treatment options for the management of memory loss and AD neuropathology in DS mouse models. We also review agerelated neuropathology, and recent findings from neuroimaging studies. The validation of appropriate DS mouse models that mimic neurodegeneration and memory loss in humans with DS can be valuable in the study of novel preventative and treatment interventions, and may be helpful in pinpointing gene-gene interactions as well as specific gene segments involved in neurodegeneration.

It is well established that individuals with Down syndrome develop Alzheimer’s disease neuropathology by middle age. Both in Alzheimer’s disease and Down syndrome, this is accompanied by the atrophy of NGF-dependent cholinergic neurons of the basal forebrain. An NGF trophic compromise in Alzheimer’s disease had been early suspected. This hypothesis was discarded with the finding of unaltered NGF mRNA synthesis and of increased NGF precursor levels (proNGF) in postmortem Alzheimer’s disease brains. The possibility of an NGF trophic disconnection has been recently revisited at the light of a newly discovered extracellular NGF metabolic pathway; where proNGF is released in an activity-dependent manner and converted by plasmin to mature NGF in the extracellular space. Mature NGF is ultimately degraded by the metalloprotease MMP-9. This pathway has been shown to be compromised in Alzheimer’s disease and Down syndrome brains, thus reviving the trophic factor hypothesis to explain the atrophy of basal forebrain cholinergic neurons in these disorders. This chapter will discuss the physiological role of NGF and its biological significance to cholinergic neurons of the CNS, and present the evidence for a dysregulation of the NGF metabolism in Alzheimer’s disease and Down syndrome.

Trisomy 21 and the consequent extra copy of the amyloid precursor protein (APP) gene and increased beta-amyloid (Aβ) peptide production underlie the universal development of Alzheimer’s disease (AD) pathology and high risk of AD dementia in people with Down syndrome (DS). Trisomy 21 and other forms of aneuploidy also arise among neurons and peripheral cells in both sporadic and familial AD and in mouse and cell models thereof, reinforcing the conclusion that AD and DS are two sides of the same coin. The demonstration that 90% of the neurodegeneration in AD can be attributed to the selective loss of aneuploid neurons generated over the course of the disease indicates that aneuploidy is an essential feature of the pathogenic pathway leading to the depletion of neuronal cell populations. Trisomy 21 mosaicism also occurs in neurons and other cells from patients with Niemann-Pick C1 disease and from patients with familial or sporadic frontotemporal lobar degeneration (FTLD), as well as in their corresponding mouse and cell models. Biochemical studies have shown that Aβ induces mitotic spindle defects, chromosome mis-segregation, and aneuploidy in cultured cells by inhibiting specific microtubule motors required for mitosis. These data indicate that neuronal trisomy 21 and other types of aneuploidy characterize and likely contribute to multiple neurodegenerative diseases and are a valid target for therapeutic intervention. For example, reducing extracellular calcium or treating cells with lithium chloride (LiCl) blocks the induction of trisomy 21 by Aβ. The latter finding is relevant in light of recent reports of a lowered risk of dementia in bipolar patients treated with LiCl and in the stabilization of cognition in AD patients treated with LiCl.

This research focuses on language processing, and more specifically on semantic processing, in children with Down Syndrome (DS). It has repeatedly been documented that children with DS display severe deficits in all language domains, semantics among others, and especially in their expressive language. Therefore, our purpose was to detect possible differences between receptive and expressive language in the semantic domain in DS and to compare semantic processing, both receptive and expressive, of children with DS with that of children with typical development. For this purpose we examined two groups of children, a group of children with Down Syndrome (DS) and a group of children with typical development (TD), aged 4-7.11 years old. Our findings proved that children with DS scored lower than typically developing children in all semantic tasks, whether receptive or expressive and that their performance was lower in the expressive language tasks than the receptive ones.

- by Dimitra Katsarou
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- Cognitive Psychology, Cognitive Science, Developmental Psychology, Semantics

- by Huntington Potter
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- Neurogenesis, Down Syndrome Language, Adult neurogenesis, Cell Cycle