Several recent epidemiological studies attempted to identify risk factors for Alzheimer’s disease. Age, family history, genetic factors (APOE genotype, trisomy 21), physical activity, and a low level of schooling are significant risk factors. In this review, we summarize the known psychosocial risk factors for the development of Alzheimer’s disease in patients with Down syndrome and their association with neuroanatomical changes in the brains of people with Down syndrome. We completed a comprehensive review of the literature on PubMed, Google Scholar, and Web of Science about psychosocial risk factors for Alzheimer’s disease, for Alzheimer’s disease in Down syndrome, and Alzheimer’s disease in Down syndrome and their association with neuroanatomical changes in the brains of people with Down syndrome. Alzheimer’s disease causes early pathological changes in individuals with Down syndrome, especially in the hippocampus and corpus callosum. People with Down syndrome living with dementia showed reduced volumes of brain areas affected by Alzheimer’s disease as the hippocampus and corpus callosum in association with cognitive decline. These changes occur with increasing age, and the presence or absence of psychosocial risk factors impacts the degree of cognitive function. Correlating Alzheimer’s disease biomarkers in Down syndrome and cognitive function scores while considering the effect of psychosocial risk factors helps us identify the mechanisms leading to Alzheimer’s disease at an early age. Also, this approach enables us to create more sensitive and relevant clinical, memory, and reasoning assessments for people with Down syndrome.
ObjectivesWe critically review research findings on the unique changes in brain structure and cognitive function characteristic of Down syndrome (DS) and summarize the similarities and differences with other neurodevelopmental disorders such as Williams syndrome, 22q11.2 deletion syndrome, and fragile X syndrome.MethodsWe conducted a meta-analysis and systematic literature review of 84 studies identified by searching PubMed, Google Scholar, and Web of Science from 1977 to October 2022. This review focuses on the following issues: (1) specific neuroanatomic and histopathological features of DS as revealed by autopsy and modern neuroimaging modalities, (2) language and memory deficits in DS, (3) the relationships between these neuroanatomical and neuropsychological features, and (4) neuroanatomic and neuropsychological differences between DS and related neurodevelopmental syndromes.ResultsNumerous post-mortem and morphometric neuroimaging investigations of individuals with DS have reported complex changes in regional brain volumes, most notably in the hippocampal formation, temporal lobe, frontal lobe, parietal lobe, and cerebellum. Moreover, neuropsychological assessments have revealed deficits in language development, emotional regulation, and memory that reflect these structural changes and are more severe than expected from general cognitive dysfunction. Individuals with DS also show relative preservation of multiple cognitive, linguistic, and social domains compared to normally developed controls and individuals with other neurodevelopmental disorders. However, all these neurodevelopment disorders exhibit substantial heterogeneity among individuals.ConclusionPeople with Down syndrome demonstrate unique neurodevelopmental abnormalities but cannot be regarded as a homogenous group. A comprehensive evaluation of individual intellectual skills is essential for all individuals with neurodevelopment disorders to develop personalized care programs.
INTRODUCTION: Down syndrome is the most common genetic cause of intellectual disability. Children and adults with Down syndrome show deficits in various aspects of language performance and explicit memory. Here, we used magnetic resonance imaging (MRI) on children and adults with Down syndrome to characterize changes in the volume of specific brain structures involved in memory and language and their relationship to features of cognitive-behavioral phenotypes. METHODS: Thirteen children and adults with the Down syndrome phenotype and 12 age- and gender-matched healthy controls (age range 4-25) have assessment by MRI and underwent a psychological evaluation for language and cognitive abilities. RESULTS: The cognitive profile of people with Down syndrome showed deficits in different cognition and language domains correlated with reduced volumes of specific regional and subregional brain structures, confirming previous related studies. Interestingly, in our study, persons with Down syndrome also showed a greater parahippocampal gyrus volume, in agreement with the results found in previous reports. CONCLUSIONS: The memory functions and language skills affected in studied individuals with Down syndrome correlate significantly with the reduced volume of specific brain regions, allowing us to understand Down syndrome's cognitive-behavioral phenotype. Our results provide an essential basis for early intervention and the design of rehabilitation management protocols.
INTRODUCTIONDown syndrome (DS) is the most common genetic cause of intellectual disability. Children and adults with DS show deficits in various aspects of language performance and explicit memory. Here we use magnetic resonance imaging (MRI) on children and adults with DS to characterize changes in the volume of specific brain structures involved in memory and language and their relationship to features of cognitive-behavioral phenotypes.METHODSThirteen children and adults with the DS phenotype and 12 age- and gender-matched healthy controls were analyzed by MRI and underwent a psychological evaluation for language and cognitive abilities.RESULTSThe neuropsychological profile of DS patients showed deficits in different cognition and language domains in correlation with reduced volumes of specific regional and subregional brain structures. Intriguingly, our DS patients showed also a reduced parahippocampal gyrus volume, in contrast with the results found by other researchers.CONCLUSIONSThe memory functions and language skills affected in our DS patients correlate significantly with the reduced volume of specific brain regions, allowing us to understand DS's cognitive-behavioral phenotype. Our results provide an essential basis for early intervention and the design of rehabilitation management protocols.
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