RESUMO
BACKGROUND: Men with fragile X-associated tremor/ataxia syndrome (FXTAS) often develop executive dysfunction, characterized by disinhibition, frontal dyscontrol of movement, and working memory and attention changes. Although cross-sectional studies have suggested that earlier executive function changes may precede FXTAS, the lack of longitudinal studies has made it difficult to address this hypothesis. OBJECTIVE: To determine whether executive function deterioration experienced by premutation carriers (PC) in daily life precedes and predicts FXTAS. METHODS: This study included 66 FMR1 PC ranging from 40 to 78 years (mean, 59.5) and 31 well-matched healthy controls (HC) ages 40 to 75 (mean, 57.7) at baseline. Eighty-four participants returned for 2 to 5 follow up visits over a duration of 1 to 9 years (mean, 4.6); 28 of the PC developed FXTAS. The Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) was completed by participants and their spouses/partners at each visit. RESULTS: Longitudinal mixed model regression analyses showed a greater decline with age in PC compared to HC on the Metacognition Index (MI; self-initiation, working memory, organization, task monitoring). Conversion to FXTAS was associated with worsening MI and Behavioral Regulation Index (BRI; inhibition, flexibility, emotion modulation). For spouse/partner report, FXTAS conversion was associated with worsening MI. Finally, increased self-report executive function problems at baseline significantly predicted later development of FXTAS. CONCLUSIONS: Executive function changes experienced by male PC represent a prodrome of the later movement disorder. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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Síndrome do Cromossomo X Frágil , Transtornos dos Movimentos , Adulto , Humanos , Masculino , Função Executiva/fisiologia , Tremor , Estudos Longitudinais , Estudos Transversais , Proteína do X Frágil da Deficiência Intelectual/genética , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/complicações , Ataxia , Transtornos dos Movimentos/complicaçõesRESUMO
In this study, the potential role and interaction of the APOε and KLOTHO genes on the penetrance of fragile X-associated tremor/ataxia syndrome (FXTAS) and on the IQ trajectory were investigated. FXTAS was diagnosed based on molecular, clinical and radiological criteria. Males with the premutation (PM) over 50 years, 165 with and 34 without an FXTAS diagnosis, were included in this study and were compared based on their APO (ε2-ε3-ε4) and KLOTHO variant (KL-VS) genotypes. The effect of APOε4 on FXTAS stage and on diagnosis did not differ significantly by KL-VS genotype with interaction effect p = 0.662 and p = 0.91, respectively. In the FXTAS individuals with an APOε2 allele, a marginal significance was observed towards a larger decline in verbal IQ (VIQ) in individuals with an APOε4 allele compared to those without an APOε4 allele (p = 0.071). In conclusion, our findings suggest that the APOε4 and KL-VS genotypes alone or through their interaction effect do not appear to predispose to either FXTAS diagnosis or stage in male carriers of the PM allele. A further study is needed to establish the trend of IQ decline in the FXTAS individuals who carry APOε4 with APOε2 compared to those without APOε4.
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Ataxia , Síndrome do Cromossomo X Frágil , Glucuronidase , Proteínas Klotho , Tremor , Humanos , Masculino , Tremor/genética , Síndrome do Cromossomo X Frágil/genética , Ataxia/genética , Idoso , Pessoa de Meia-Idade , Glucuronidase/genética , Apolipoproteínas E/genética , Penetrância , Genótipo , Alelos , Idoso de 80 Anos ou mais , Predisposição Genética para DoençaRESUMO
Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) is a neurodegenerative disorder associated with the FMR1 premutation. Currently, it is not possible to determine when and if individual premutation carriers will develop FXTAS. Thus, with the aim to identify biomarkers for early diagnosis, development, and progression of FXTAS, along with associated dysregulated pathways, we performed blood proteomic profiling of premutation carriers (PM) who, as part of an ongoing longitudinal study, emerged into two distinct groups: those who developed symptoms of FXTAS (converters, CON) over time (at subsequent visits) and those who did not (non-converters, NCON). We compared these groups to age-matched healthy controls (HC). We assessed CGG repeat allele size by Southern blot and PCR analysis. The proteomic profile was obtained by liquid chromatography mass spectrometry (LC-MS/MS). We identified several significantly differentiated proteins between HC and the PM groups at Visit 1 (V1), Visit 2 (V2), and between the visits. We further reported the dysregulated protein pathways, including sphingolipid and amino acid metabolism. Our findings are in agreement with previous studies showing that pathways involved in mitochondrial bioenergetics, as observed in other neurodegenerative disorders, are significantly altered and appear to contribute to the development of FXTAS. Lastly, we compared the blood proteome of the PM who developed FXTAS over time with the CSF proteome of the FXTAS patients recently reported and found eight significantly differentially expressed proteins in common. To our knowledge, this is the first report of longitudinal proteomic profiling and the identification of unique biomarkers and dysregulated protein pathways in FXTAS.
Assuntos
Proteoma , Proteômica , Humanos , Cromatografia Líquida , Estudos Longitudinais , Espectrometria de Massas em Tandem , Tremor , Biomarcadores , Proteína do X Frágil da Deficiência Intelectual/genéticaRESUMO
Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) is a neurodegenerative disorder associated with the FMR1 premutation. It is currently unknown when, and if, individual premutation carriers will develop FXTAS. Thus, with the aim of identifying biomarkers for early diagnosis, development, and progression of FXTAS, we performed global metabolomic profiling of premutation carriers (PM) who, as part of an ongoing longitudinal study, emerged into two distinct categories: those who developed symptoms of FXTAS (converters, CON) at subsequent visits and those who did not (non-converters, NCON) and we compared to age-matched healthy controls (HC). We assessed CGG repeat allele size by Southern Blot and PCR analysis. Metabolomic profile was obtained by ultra-performance liquid chromatography, accurate mass spectrometer, and an Orbitrap mass analyzer. In this study we found 47 metabolites were significantly dysregulated between HC and the premutation groups (PM). Importantly, we identified 24 metabolites that showed significant changes in expression in the CON as compared to the NCON both at V1 and V2, and 70 metabolites in CON as compared to NCON but only at V2. These findings suggest the potential role of the identified metabolites as biomarkers for early diagnosis and for FXTAS disease progression, respectively. Interestingly, the majority of the identified metabolites were lipids, followed by amino acids. To our knowledge, this the first report of longitudinal metabolic profiling and identification of unique biomarkers of FXTAS. The lipid metabolism and specifically the sub pathways involved in mitochondrial bioenergetics, as observed in other neurodegenerative disorders, are significantly altered in FXTAS.
Assuntos
Ataxia/genética , Ataxia/metabolismo , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/metabolismo , Metabolismo dos Lipídeos/genética , Tremor/genética , Tremor/metabolismo , Adulto , Alelos , Biomarcadores/metabolismo , Feminino , Proteína do X Frágil da Deficiência Intelectual/metabolismo , Heterozigoto , Humanos , Estudos Longitudinais , MasculinoRESUMO
Although prior studies have compared sensory event-related potential (ERP) responses between groups of autistic and typically-developing participants, it is unclear how heterogeneity contributes to the results of these studies. The present study used examined individual differences in these responses. 130 autistic children and 81 typically-developing children, aged between 2 and 5 years, listened to tones at four identity levels while 61-channel electroencephalography was recorded. Hierarchical clustering was used to group participants based on rescaled ERP topographies between 51 and 350 ms. The hierarchical clustering analysis revealed substantial heterogeneity. Some of the seven clusters defined in this analysis were characterized by prolonged fronto-central positivities and/or weak or absent N2 negativities. However, many other participants fell into clusters in which N2 responses were present at varying latencies. Atypical response morphologies such as absent N2 responses and/or prolonged positive-going responses found in some autistic participants may account for prior research findings of attenuated N2 amplitudes in autism. However, there was also considerable overlap between groups, with participants of both groups appearing in all clusters. These results emphasize the utility of using clustering to explore individual differences in brain responses, which can expand on and clarify the results of analyses of group mean differences.
Assuntos
Transtorno Autístico , Estimulação Acústica , Criança , Pré-Escolar , Análise por Conglomerados , Eletroencefalografia , Potenciais Evocados , Potenciais Evocados Auditivos , HumanosRESUMO
BACKGROUND: Fragile X premutation carriers are at increased risk for fragile X-associated tremor ataxia syndrome (FXTAS), but to date we know little about prediction of onset and rate of progression and even less about treatment of this neurodegenerative disease. Thus, the longitudinal study of carriers, and the identification of potential biomarkers and prodromal states, is essential. Here we present results of baseline assessments from an ongoing longitudinal project. METHODS: The cohort consisted of 73 men, 48 with the fragile X mental retardation 1 (FMR1) premutation (55-200 cytosine-cytosine-guanine or CGG repeats) and 25 well-matched controls (< 40 repeats) aged between 40 and 75 years. At enrollment, none met criteria for FXTAS or had any clinically significant tremor or ataxia by blinded neurological examination. The battery consisted of measures of visual memory, spatial working memory, response inhibition, motor speed and control, planning and problem solving, sustained attention, and a standardized movement disorder evaluation. RESULTS: Contrary to expectations, there were no significant differences between premutation carriers and controls on any measure of executive function. However, the premutation carriers had significantly longer manual movement and reaction times than controls, and the significant interaction between CGG repeat and age revealed the slowest movement times among older carriers with higher CGG repeat alleles. A subset of premutation carriers had marginally lower scores on the ataxia evaluation, and they performed no differently from controls on the parkinsonism assessment. CONCLUSION: Early-developing cerebellar or fronto-motor tract white matter changes, previously documented in MRI studies, may underlie motor slowing that occurs before clinically observable neurological symptoms associated with FXTAS. © 2018 International Parkinson and Movement Disorder Society.
Assuntos
Envelhecimento , Ataxia/genética , Proteína do X Frágil da Deficiência Intelectual/genética , Síndrome do Cromossomo X Frágil/genética , Sintomas Prodrômicos , Tremor/genética , Expansão das Repetições de Trinucleotídeos/genética , Adulto , Fatores Etários , Idoso , Ataxia/complicações , Atenção , Estudos de Coortes , Feminino , Síndrome do Cromossomo X Frágil/complicações , Humanos , Inibição Psicológica , Inteligência , Masculino , Transtornos da Memória/etiologia , Memória de Curto Prazo/fisiologia , Pessoa de Meia-Idade , Estimulação Luminosa , RNA Mensageiro/metabolismo , Tempo de Reação , Análise de Regressão , Tremor/complicaçõesRESUMO
Several studies have demonstrated increased rates of anxiety and depressive disorders among female carriers of the fragile X premutation. However, the majority of these studies focused on mothers of children with fragile X syndrome, who experience higher rates of parenting stress that may contribute to the emergence of these disorders. The present study compared psychiatric symptom presentation (utilizing measures of current symptoms and lifetime DSM-IV Axis I disorders) in 24 female carriers without affected children (mean age = 32.1 years) to 26 non-carrier women from the community (mean age = 30.5 years). We also examined the association between CGG repeat size (adjusted for X activation ratio) and mRNA, with severity of psychiatric symptoms. Women with the premutation reported significantly elevated symptoms of anxiety, depression, interpersonal sensitivity, obsessive-compulsiveness, and somatization relative to controls during the past week. Carriers had significantly higher rates of lifetime social phobia (42.3%) compared to controls (12.5%); however, this comparison did not remain significant after multiple comparison adjustment. Rates of other psychiatric disorders were not significantly elevated relative to controls, though it should be noted that lifetime rates among controls were much higher than previously published population estimates. Although the sample is relatively small, the study of this unique cohort suggests the premutation confers risk for mood and anxiety disorders independent of the stress of parenting children with FXS. Screening for psychiatric disorders in women with the premutation, even before they become parents, is important and highly encouraged. © 2016 Wiley Periodicals, Inc.
Assuntos
Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/psicologia , Adulto , Afeto , Ansiedade/genética , Transtornos de Ansiedade/genética , Depressão/genética , Transtorno Depressivo/genética , Feminino , Proteína do X Frágil da Deficiência Intelectual/genética , Humanos , Transtornos Mentais/etiologia , Transtornos Mentais/genética , Repetições de Trinucleotídeos/genéticaRESUMO
Mutations of the fragile X mental retardation 1 (FMR1) gene are the genetic cause of fragile X syndrome (FXS). The presence of significant socioemotional problems has been well documented in FXS although the brain basis of those deficits remains unspecified. Here, we investigated amygdala dysfunction and its relation to socioemotional deficits and FMR1 gene expression in children and adolescents on the FX spectrum (i.e., individuals whose trinucleotide CGG repeat expansion from 55 to over 200 places them somewhere within the fragile X diagnostic range from premutation to full mutation). Participants performed an fMRI task in which they viewed fearful, happy, and scrambled faces. Neuroimaging results demonstrated that FX participants revealed significantly attenuated amygdala activation in Fearful > Scrambled and Fearful > Happy contrasts compared with their neurotypical counterparts, while showing no differences in amygdala volume. Furthermore, we found significant relationships between FMR1 gene expression, anxiety/social dysfunction scores, and reduced amygdala activation in the FX group. In conclusion, we report novel evidence regarding a dosage response of the FMR1 gene on fear-specific functions of the amygdala, which is associated with socioemotional deficits in FXS.
Assuntos
Tonsila do Cerebelo/patologia , Medo , Proteína do X Frágil da Deficiência Intelectual/genética , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/patologia , Repetições de Trinucleotídeos/genética , Adolescente , Tonsila do Cerebelo/irrigação sanguínea , Estudos de Casos e Controles , Córtex Cerebral/irrigação sanguínea , Córtex Cerebral/patologia , Criança , Transtornos Cognitivos/etiologia , Movimentos Oculares/fisiologia , Feminino , Síndrome do Cromossomo X Frágil/complicações , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Testes Neuropsicológicos , Oxigênio/sangue , Escalas de Graduação PsiquiátricaRESUMO
Fragile X premutation carriers (fXPC) are characterized by 55-200 CGG trinucleotide repeats in the 5' untranslated region on the Xq27.3 site of the X chromosome. Clinically, they are associated with the fragile X-Associated Tremor/Ataxia Syndrome, a late-onset neurodegenerative disorder with diffuse white matter neuropathology. Here, we conducted first-ever graph theoretical network analyses in fXPCs using 30-direction diffusion-weighted magnetic resonance images acquired from 42 healthy controls aged 18-44 years (HC; 22 male and 20 female) and 46 fXPCs (16 male and 30 female). Globally, we found no differences between the fXPCs and HCs within each gender for all global graph theoretical measures. In male fXPCs, global efficiency was significantly negatively associated with the number of CGG repeats. For nodal measures, significant group differences were found between male fXPCs and male HCs in the right fusiform and the right ventral diencephalon (for nodal efficiency), and in the left hippocampus [for nodal clustering coefficient (CC)]. In female fXPCs, CC in the left superior parietal cortex correlated with counting performance in an enumeration task.
Assuntos
Encéfalo/patologia , Cromossomos Humanos X/genética , Proteína do X Frágil da Deficiência Intelectual/genética , Expansão das Repetições de Trinucleotídeos , Adolescente , Adulto , Ataxia/genética , Conectoma , Imagem de Difusão por Ressonância Magnética , Feminino , Síndrome do Cromossomo X Frágil/genética , Humanos , Masculino , Modelos Neurológicos , Vias Neurais/patologia , Tamanho do Órgão , Testes Psicológicos , Caracteres Sexuais , Tremor/genética , Adulto JovemRESUMO
Autistic individuals often exhibit motor atypicalities, which may relate to difficulties in social communication. This study utilized a smart tablet activity to computationally characterize motor control by testing adherence to the two-thirds power law (2/3 PL), which captures a systematic covariation between velocity and curvature in motor execution and governs many forms of human movement. Children aged 4-8 years old participated in this study, including 24 autistic children and 33 typically developing children. Participants drew and traced ellipses on an iPad. We extracted data from finger movements on the screen, and computed adherence to the 2/3 PL and other kinematic metrics. Measures of cognitive and motor functioning were also collected. In comparison to the typically developing group, the autistic group demonstrated greater velocity modulation between curved and straight sections of movement, increased levels of acceleration and jerk, and greater intra- and inter-individual variability across several kinematic variables. Further, significant motor control development was observed in typically developing children, but not in those with autism. This study is the first to examine motor control adherence to the 2/3 PL in autistic children, revealing overall diminished motor control. Less smooth, more varied movement and an indication of developmental stasis in autistic children were observed. This study offers a novel tool for computational characterization of the autism motor signature in children's development, demonstrating how smart tablet technology enables accessible assessment of children's motor performance in an objective, quantifiable and scalable manner.
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The autistic-developed monotropism account suggests that atypical, domain-general attentional hyper-focus on interests is a central aspect of autism, but domain-general attention differences in autism can manifest differently. Prior research suggests autistic children are often slow to disengage attention from stimuli-a pattern often called "sticky attention"-and that they can show reduced novelty preference. These attentional patterns could influence sensory experiences and learning. We used eye-tracking to investigate novelty preference and "sticky attention" in young autistic children; we also examined whether attentional patterns were related to cognitive abilities and caregiver-reported sensory responsiveness. A total of 46 autistic and 28 nonautistic participants, aged between 2 and 4 years, provided usable data. We found no evidence that autistic children exhibited greater "sticky attention" than nonautistics, but "sticky attention" in autism was associated with more caregiver-reported sensory hyper-responsiveness, seeking/interests, and enhanced perception. Autistic children also nonsignificantly trended toward exhibiting reduced novelty preference. Unexpectedly, the time-course of this trending novelty preference difference implied it was not driven by reduced orienting to novelty, but increased returning to already-familiarized stimuli: what we call "springy attention." Exploratory analyses of data from the attentional disengagement task suggest autistic participants may have exhibited greater "springy attention," though further research with paradigms optimized for measuring this construct should confirm this. Importantly, "springy attention" was robustly related to reduced cognitive abilities and greater caregiver-reported hypo-responsiveness. Thus, this study illuminates two distinct domain-general attentional patterns, each with distinct correlates in young autistic children, which could have important implications for understanding autistic children's learning, development, and experiences.
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FMR1 premutation carriers (55-200 CGG repeats) are at risk of developing fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder associated with motor and cognitive impairment. Bilateral hyperintensities of the middle cerebellar peduncles (MCP sign) are the major radiological hallmarks of FXTAS. In the general population, enlarged perivascular spaces (PVS) are biomarkers of small vessel disease and glymphatic dysfunction and are associated with cognitive decline. Our aim was to determine if premutation carriers show higher ratings of PVS than controls and whether enlarged PVS are associated with motor and cognitive impairment, MRI features of neurodegeneration, cerebrovascular risk factors and CGG repeat length. We evaluated 655 MRIs (1-10 visits/participant) from 229 carriers (164 with FXTAS and 65 without FXTAS) and 133 controls. PVS in the basal ganglia (BG-EPVS), centrum semiovale, and midbrain were evaluated with a semiquantitative scale. Mixed-effects models were used for statistical analysis adjusting for age. In carriers with FXTAS, we revealed that (1) BG-PVS ratings were higher than those of controls and carriers without FXTAS; (2) BG-PVS severity was associated with brain atrophy, white matter hyperintensities, enlarged ventricles, FXTAS stage and abnormal gait; (3) age-related increase in BG-PVS was associated with cognitive dysfunction; and (4) PVS ratings of all three regions showed robust associations with CGG repeat length and were higher in carriers with the MCP sign than carriers without the sign. This study demonstrates clinical relevance of PVS in FXTAS especially in the basal ganglia region and suggests microangiopathy and dysfunctional cerebrospinal fluid circulation in FXTAS physiopathology.
Assuntos
Ataxia , Proteína do X Frágil da Deficiência Intelectual , Síndrome do Cromossomo X Frágil , Sistema Glinfático , Imageamento por Ressonância Magnética , Tremor , Humanos , Masculino , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/diagnóstico por imagem , Síndrome do Cromossomo X Frágil/patologia , Pessoa de Meia-Idade , Idoso , Proteína do X Frágil da Deficiência Intelectual/genética , Tremor/genética , Tremor/diagnóstico por imagem , Tremor/patologia , Ataxia/genética , Ataxia/diagnóstico por imagem , Ataxia/patologia , Sistema Glinfático/diagnóstico por imagem , Sistema Glinfático/patologia , Fatores de Risco , Heterozigoto , Transtornos Cerebrovasculares/genética , Transtornos Cerebrovasculares/diagnóstico por imagem , Transtornos Cerebrovasculares/patologia , Disfunção Cognitiva/genética , Disfunção Cognitiva/diagnóstico por imagem , Disfunção Cognitiva/patologia , Disfunção Cognitiva/etiologia , Encéfalo/diagnóstico por imagem , Encéfalo/patologiaRESUMO
The fragile X mental retardation 1 (FMR1) gene plays an important role in the development and maintenance of neuronal circuits that are essential for cognitive functioning. We explored the functional linkage(s) among lymphocytic FMR1 gene expression, brain structure, and working memory in healthy adult males. We acquired T1-weighted and diffusion tensor imaging from 37 males (18-80 years, mean ± SD= 40.7 ± 17.3 years) with normal FMR1 alleles and performed genetic and working memory assessments. Brain measurements were obtained from fiber tracts important for working memory (i.e. the arcuate fasciculus, anterior cingulum bundle, inferior longitudinal fasciculus, and the genu and anterior body of the corpus callosum), individual voxels, and whole brain. Both FMR1 mRNA and protein (FMRP) levels exhibited significant associations with brain measurements, with FMRP correlating positively with gray matter volume and white matter structural organization, and FMR1 mRNA negatively with white matter structural organization. The correlation was widespread, impacting rostral white matter and 2 working-memory fiber tracts for FMRP, and all cerebral white matter areas except the fornix and cerebellar peduncles and all 4 fiber tracts for FMR1 mRNA. In addition, the levels of FMR1 mRNA as well as the fiber tracts demonstrated a significant correlation with working memory performance. While FMR1 mRNA exhibited a negative correlation with working memory, fiber tract structural organization showed a positive correlation. These findings suggest that the FMR1 gene is a genetic factor common for both working memory and brain structure, and has implications for our understanding of the transmission of intelligence and brain structure.
Assuntos
Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Proteína do X Frágil da Deficiência Intelectual/fisiologia , Memória de Curto Prazo/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Alelos , Imagem de Difusão por Ressonância Magnética , Humanos , Interpretação de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Approximately 40% of males with the fragile X premutation develop fragile X-associated tremor/ataxia syndrome after age 50. Although the thalamus and basal ganglia play a crucial role in movement disorders, their involvement in fragile X premutation carriers has not been systematically investigated. The current study characterized structural abnormalities associated with fragile X premutation carriers (with and without fragile X-associated tremor/ataxia syndrome) in the thalamus, caudate nucleus, putamen, and globus pallidus using T1-weighted and diffusion tensor imaging. Male premutation carriers with fragile X-associated tremor/ataxia syndrome showed significant volume atrophy and diffusion-weighted signal loss in all 4 structures compared with the control group. They also exhibited volume atrophy and diffusion-weighted signal loss in the thalamus and striatum compared with the premutation carriers without fragile X-associated tremor/ataxia syndrome. Importantly, many of the measurements exhibited robust correlations with symptom severity, with volume and diffusion-weighted imaging measurements displaying negative correlations and fractional anisotropy measurements displaying positive correlations. The current study demonstrated involvement of all 4 subcortical gray matter structures in fragile X-associated tremor/ataxia syndrome, with significant volume atrophy, and possible iron deposition indicated by the diffusion-weighted signal loss. The significant correlation between the subcortical measurements and symptom severity suggests the benefits of tracking structural changes in subcortical gray matter in future longitudinal studies for early detection and disease monitoring. © 2013 Movement Disorder Society.
Assuntos
Encéfalo/patologia , Imagem de Tensor de Difusão , Síndrome do Cromossomo X Frágil/patologia , Imagem Multimodal , Idoso , Idoso de 80 Anos ou mais , Atrofia , Feminino , Proteína do X Frágil da Deficiência Intelectual/genética , Síndrome do Cromossomo X Frágil/genética , Lateralidade Funcional , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Razão de ChancesRESUMO
Prior studies suggest that habituation of sensory responses is reduced in autism and that diminished habituation could be related to atypical autistic sensory experiences, for example, by causing brain responses to aversive stimuli to remain strong over time instead of being suppressed. While many prior studies exploring habituation in autism have repeatedly presented identical stimuli, other studies suggest group differences can still be observed in habituation to intermittent stimuli. The present study explored habituation of electrophysiological responses to auditory complex tones of varying intensities (50-80 dB SPL), presented passively in an interleaved manner, in a well-characterized sample of 127 autistic (MDQ = 65.41, SD = 20.54) and 79 typically developing (MDQ = 106.02, SD = 11.50) children between 2 and 5 years old. Habituation was quantified as changes in the amplitudes of single-trial responses to tones of each intensity over the course of the experiment. Habituation of the auditory N2 response was substantially reduced in autistic participants as compared to typically developing controls, although diagnostic groups did not clearly differ in habituation of the P1 response. Interestingly, the P1 habituated less to loud 80 dB sounds than softer sounds, whereas the N2 habituated less to soft 50 dB sounds than louder sounds. No associations were found between electrophysiological habituation and cognitive ability or participants' caregiver-reported sound tolerance (Sensory Profile Hyperacusis Index). The results present study results extend prior research suggesting habituation of certain sensory responses is reduced in autism; however, they also suggest that habituation differences observed using this study's paradigm might not be a primary driver of autistic participants' real-world sound intolerance.
Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Humanos , Criança , Pré-Escolar , Estimulação Acústica/métodos , Habituação Psicofisiológica/fisiologia , EncéfaloRESUMO
Background: Men with fragile X-associated tremor/ataxia syndrome (FXTAS) often develop executive dysfunction, characterized by disinhibition, frontal dyscontrol of movement, and working memory and attention changes. Although cross-sectional studies have suggested that earlier executive function changes may precede FXTAS, the lack of longitudinal studies have made it difficult to address this hypothesis. Methods: This study included 66 FMR1 premutation carriers (PC) ranging from 40-78 years (Mean=59.5) and 31 well-matched healthy controls (HC) ages 40-75 (Mean 57.7) at baseline. Eighty-four participants returned for 2-5 follow up visits over a duration of 1 to 9 years (Mean=4.6); 28 of the PC developed FXTAS. The Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) was completed by participants and their spouses/partners at each visit. Results: Longitudinal mixed model regression analyses showed a greater decline with age in PC compared to HC on the Metacognition Index (MI; self-initiation, working memory, organization, task monitoring). Conversion to FXTAS was associated with worsening MI and Behavioral Regulation Index (BRI; inhibition, flexibility, emotion modulation). For spouse/partner report, FXTAS conversion was associated with worsening MI. Finally, BRIEF-A executive function problems at baseline significantly predicted later development of FXTAS. Conclusions: These findings suggest that executive function changes represent a prodrome of the later movement disorder.
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The premutation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene is characterized by an expansion of the CGG trinucleotide repeats (55 to 200 CGGs) in the 5' untranslated region and increased levels of FMR1 mRNA. Molecular mechanisms leading to fragile X-premutation-associated conditions (FXPAC) include cotranscriptional R-loop formations, FMR1 mRNA toxicity through both RNA gelation into nuclear foci and sequestration of various CGG-repeat-binding proteins, and the repeat-associated non-AUG (RAN)-initiated translation of potentially toxic proteins. Such molecular mechanisms contribute to subsequent consequences, including mitochondrial dysfunction and neuronal death. Clinically, premutation carriers may exhibit a wide range of symptoms and phenotypes. Any of the problems associated with the premutation can appropriately be called FXPAC. Fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND) can fall under FXPAC. Understanding the molecular and clinical aspects of the premutation of the FMR1 gene is crucial for the accurate diagnosis, genetic counseling, and appropriate management of affected individuals and families. This paper summarizes all the known problems associated with the premutation and documents the presentations and discussions that occurred at the International Premutation Conference, which took place in New Zealand in 2023.
Assuntos
Proteína do X Frágil da Deficiência Intelectual , Síndrome do Cromossomo X Frágil , Humanos , Proteína do X Frágil da Deficiência Intelectual/genética , Proteína do X Frágil da Deficiência Intelectual/metabolismo , Mutação/genética , RNA Mensageiro/metabolismo , Expansão das Repetições de Trinucleotídeos/genética , Síndrome do Cromossomo X Frágil/diagnóstico , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/terapiaRESUMO
Fragile X syndrome is the most common cause of inherited intellectual impairment and the most common single-gene cause of autism. Individuals with fragile X syndrome present with a neurobehavioural phenotype that includes selective deficits in spatiotemporal visual perception associated with neural processing in frontal-parietal networks of the brain. The goal of the current study was to examine whether reduced resolution of spatial and/or temporal visual attention may underlie perceptual deficits related to fragile X syndrome. Eye tracking was used to psychophysically measure the limits of spatial and temporal attention in infants with fragile X syndrome and age-matched neurotypically developing infants. Results from these experiments revealed that infants with fragile X syndrome experience drastically reduced resolution of temporal attention in a genetic dose-sensitive manner, but have a spatial resolution of attention that is not impaired. Coarse temporal attention could have significant knock-on effects for the development of perceptual, cognitive and motor abilities in individuals with the disorder.
Assuntos
Atenção/fisiologia , Síndrome do Cromossomo X Frágil/fisiopatologia , Percepção Espacial/fisiologia , Percepção do Tempo/fisiologia , Percepção Visual/fisiologia , Pré-Escolar , Sensibilidades de Contraste/fisiologia , Movimentos Oculares/fisiologia , Feminino , Síndrome do Cromossomo X Frágil/psicologia , Humanos , Lactente , Masculino , Testes NeuropsicológicosRESUMO
Fragile X-associated tremor/ataxia syndrome is a neurodegenerative disorder that primarily affects older male premutation carriers of the fragile X mental retardation gene. Although its core symptoms are mainly characterized by motor problems such as intention tremor and gait ataxia, cognitive decline and psychiatric problems are also commonly observed. Past radiological and histological approaches have focused on prominent neurodegenerative changes in specific brain structures including the cerebellum and limbic areas. However, quantitative investigations of the regional structural abnormalities have not been performed over the whole brain. In this study, we adopted the voxel-based morphometry method together with regions of interest analysis for the cerebellum to examine the pattern of regional grey matter change in the male premutation carriers with and without fragile X-associated tremor/ataxia syndrome. In a comparison with healthy controls, we found striking grey matter loss of the patients with fragile X-associated tremor/ataxia syndrome in multiple regions over the cortical and subcortical structures. In the cerebellum, the anterior lobe and the superior posterior lobe were profoundly reduced in both vermis and hemispheres. In the cerebral cortex, clusters of highly significant grey matter reduction were found in the extended areas in the medial surface of the brain, including the dorsomedial prefrontal cortex, anterior cingulate cortex and precuneus. The other prominent grey matter loss was found in the lateral prefrontal cortex, orbitofrontal cortex, amygdala and insula. Although the voxel-wise comparison between the asymptomatic premutation group and healthy controls did not reach significant difference, a regions of interest analysis revealed significant grey matter reduction in anterior subregions of the cerebellar vermis and hemisphere in the asymptomatic premutation group. Correlation analyses using behavioural scales of the premutation groups showed significant associations between grey matter loss in the left amygdala and increased levels of obsessive-compulsiveness and depression, and between decreased grey matter in the left inferior frontal cortex and anterior cingulate cortex and poor working memory performance. Furthermore, regression analyses revealed a significant negative effect of CGG repeat size on grey matter density in the dorsomedial frontal regions. A significant negative correlation with the clinical scale for the severity of fragile X-associated tremor/ataxia syndrome was found in a part of the vermis. These observations reveal the anatomical patterns of the neurodegenerative process that underlie the motor, cognitive and psychiatric problems of fragile X-associated tremor/ataxia syndrome, together with incipient structural abnormalities that may occur before the clinical onset of this disease.
Assuntos
Cerebelo/patologia , Proteína do X Frágil da Deficiência Intelectual/genética , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/patologia , Mutação/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Mapeamento Encefálico , Transtornos Cognitivos/etiologia , Feminino , Síndrome do Cromossomo X Frágil/complicações , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Testes Psicológicos , Índice de Gravidade de Doença , Estatística como AssuntoRESUMO
This study uses factor mixture modelling of the Short Sensory Profile (SSP) at two time points to describe subgroups of young autistic and typically-developing children. This approach allows separate SSP subscales to influence overall SSP performance differentially across subgroups. Three subgroups were described, one including almost all typically-developing participants plus many autistic participants. SSP performance of a second, largely-autistic subgroup was predominantly shaped by a subscale indexing behaviours of low energy/weakness. Finally, the third subgroup, again largely autistic, contained participants with low (or more "atypical") SSP scores across most subscales. In this subgroup, autistic participants exhibited large P1 amplitudes to loud sounds. Autistic participants in subgroups with more atypical SSP scores had higher anxiety and more sleep disturbances.