Shedding light on motor premanifest myotonic dystrophy type 1: A molecular, muscular and central nervous system follow-up study.

BACKGROUND AND PURPOSE: Myotonic dystrophy type 1 (DM1) is a hereditary and multisystemic disease that is characterized by heterogeneous manifestations. Although muscular impairment is central to DM1, a premanifest DM1 form has been proposed for those characterized by the absence of muscle signs in precursory phases. Nevertheless, subtle signs and/or symptoms related to other systems, such as the central nervous system (CNS), may emerge and progress gradually. This study aimed to validate the premanifest DM1 concept and to characterize and track affected individuals from a CNS centred perspective. METHODS: Retrospective data of 120 participants (23 premanifest DM1, 25 manifest DM1 and 72 healthy controls) were analysed transversally and longitudinally (over 11.17 years). Compiled data included clinical, neuropsychological and neuroradiological (brain volume and white matter lesion, WML) measures taken at two time points. RESULTS: Manifest DM1 showed significantly more molecular affectation, worse performance on neuropsychological domains, lower grey and white matter volumes and a different pattern of WMLs than premanifest DM1. The latter was slightly different from healthy controls regarding brain volume and WMLs. Additionally, daytime sleepiness and molecular expansion size explained 50% of the variance of the muscular deterioration at follow-up in premanifest individuals. CONCLUSIONS: Premanifest DM1 individuals showed subtle neuroradiological alterations, which suggests CNS involvement early in the disease. Based on follow-up data, a debate emerges around the existence of a 'non-muscular DM1' subtype and/or a premanifest phase, as a precursory stage to other DM1 manifestations.

Transcriptional signatures of synaptic vesicle genes define myotonic dystrophy type I neurodegeneration.

AIM: To delineate the neurogenetic profiles of brain degeneration patterns in myotonic dystrophy type I (DM1). METHODS: In two cohorts of DM1 patients, brain maps of volume loss (VL) and neuropsychological deficits (NDs) were intersected to large-scale transcriptome maps provided by the Allen Human Brain Atlas (AHBA). For validation, neuropathological and RNA analyses were performed in a small series of DM1 brain samples. RESULTS: Twofold: (1) From a list of preselected hypothesis-driven genes, confirmatory analyses found that three genes play a major role in brain degeneration: dystrophin (DMD), alpha-synuclein (SNCA) and the microtubule-associated protein tau (MAPT). Neuropathological analyses confirmed a highly heterogeneous Tau-pathology in DM1, different to the one in Alzheimer's disease. (2) Exploratory analyses revealed gene clusters enriched for key biological processes in the central nervous system, such as synaptic vesicle recycling, localization, endocytosis and exocytosis, and the serotonin and dopamine neurotransmitter pathways. RNA analyses confirmed synaptic vesicle dysfunction. CONCLUSIONS: The combination of large-scale transcriptome interactions with brain imaging and cognitive function sheds light on the neurobiological mechanisms of brain degeneration in DM1 that might help define future therapeutic strategies and research into this condition.

CNS involvement in myotonic dystrophy type 1: does sex play a role?

Introduction: Myotonic dystrophy type 1 (DM1) is a hereditary neuromuscular disorder affecting the central nervous system (CNS). Although sex differences have been explored in other neuromuscular disorders, research on this topic in DM1 remains limited. The present study aims to analyze sex differences (both the patient's and disease-transmitting parent's sex) with a focus on CNS outcomes. Methods: Retrospective data from 146 non-congenital DM1 patients were analyzed, including clinical, molecular, neuropsychological, and neuroradiological data. Sex and inheritance pattern differences were analyzed using t-tests, and ANOVA analyses were conducted to address the interactions. Results: Overall, no significant sex differences were observed except in certain cognitive domains. However, individuals with maternal inheritance showed larger CTG expansion size, lower estimated IQs, and poorer performance on visual memory, executive functions, and language domains than those with paternal inheritance. Notably, IQ performance was independently influenced by inheritance pattern and CTG expansion. Discussion: This study is the first to delve into sex differences in DM1 with a focus on CNS outcomes. While the results revealed the absence of a sex-specific clinic-molecular profile, more substantial CNS differences were observed between patients with maternal and paternal inheritance patterns. The hypothetical existence of genomic imprinting and its potential mechanism are discussed. These findings hold potential implications for aiding clinical management by improving genetic counseling and predicting disease severity and prognosis.

Patient-Reported Outcome Measures in Neuromuscular Diseases: A Scoping Review.

 Patient-reported outcome measures (PROMs) are valuable in comprehensively understanding patients' health experiences and informing healthcare decisions in research and clinical care without clinicians' input. Until now, no central resource containing information on all PROMS in neuromuscular diseases (NMD) is available, hindering the comparison and choice of PROMs used to monitor NMDs and appropriately reflect the patient's voice. This scoping review aimed to present a comprehensive assessment of the existing literature on using PROMs in children and adults with NMD. A scoping methodology was followed using Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidelines to assess the literature on PROMs in NMDs. Eligibility criteria encompassed articles describing psychometric development or evaluation of generic or disease-specific PROM-based instruments for adults and children with specific NMDs. The data charting process involved extracting measurement properties of included PROMs, comprising validity, reliability, responsiveness, and interpretability information. The review identified 190 PROMs evaluated across 247 studies in individuals with NMDs. The majority of PROMs were disease specific. The physical functioning domain was most assessed. Validity was the most frequently investigated measurement property, with a limited number of PROMs sufficiently evaluated for a range of psychometric characteristics. There is a strong need for further research on the responsiveness and interpretability of PROMs and the development of PROMs on social functioning in NMD.

Visuoconstructional impairment in DM1: exploring underlying cognitive processes through the Rey complex figure.

INTRODUCTION: Among the cognitive difficulties shown by myotonic dystrophy type 1 (DM1) patients, visuoconstructional impairment - specifically measured with the Rey-Osterrieth Complex Figure Test (RCFT) - is particularly notable. This study aimed to analyze the performance of DM1 patients and healthy controls (HC) in the RCFT, using different correction systems in order to explore the cognitive processes underlying the poor performance and its associations with other signs and symptoms. METHODS: Data from 66 DM1 patients and 68 HC were included in this study. All participants had a comprehensive neuropsychological assessment, including the RCFT, which was scored using both the traditional Osterrieth and the Boston Qualitative Scoring System (BQSS) procedures. ANCOVA and Spearman's correlation analyses were conducted. RESULTS: DM1 Patients obtained significantly poorer scores than HC on the RCFT using both correction systems. Regarding BQSS, patients performed worse than HC in both main indexes (Copy Presence Accuracy-CPA and Organization-ORG), and specifically on scores of Configural accuracy, Planning, and Perseveration. Both main indexes - but especially CPA - showed significant and strong correlations with several clinical and cognitive variables. CONCLUSIONS: Both visuoconstruction and organizational impairments underlie the poor RCFT performance in DM1. Moreover, visuoconstruction ability appears to be sensitive to the clinical hallmarks of DM1 patients. The RCFT is proposed as a gold standard in DM1 assessment and the merits of using alternative scoring systems are discussed.

Executive functions and daily functioning in myotonic dystrophy type 1 ecological assessment with virtual reality.

Central nervous system dysfunction is characteristic of patients with myotonic dystrophy type 1 (DM1). Although no consensus exists regarding the exact cognitive profile of these patients, executive dysfunction has been suggested to play a role. Due to the impact of executive functions on daily performance, this study aimed to describe executive functioning in an ecological manner and to analyze its impact - and that of other clinical variables - on the functional performance of DM1 patients. A Virtual Reality executive functioning test (Nesplora Ice Cream), the Wechsler Adult Intelligence Scale-Fourth Edition, and self-report questionnaires (AES, FSS, ESS and LIFE-H) were administered to 20 patients. Statistical analyses included correlation and multiple regression analyses to analyze the best predictors of daily performance. DM1 patients did not show major difficulties in the executive functioning tasks or in their overall performance on daily habits. However, both cold and hot executive functions still seem necessary for the correct accomplishment of life habits, since planning and level of apathy explained 47.6% of the total variance of daily functioning. This was the first study to assess executive functions in DM1 using Virtual Reality, and our findings open a debate about their actual impairment in this population.

A validated WAIS-IV short-form to estimate intellectual functioning in myotonic dystrophy type 1.

Currently, no rapid and specific instrument is available to briefly estimate intelligence in patients with myotonic dystrophy type 1 (DM1), a multisystemic disease that involves the CNS and is associated with cognitive deficits and low intellectual functioning. This study aimed to develop a DM1-specific and valid short-form of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) to estimate intellectual functioning in this population. Thirty non-congenital DM1 patients (10 female; mean age=46.77; SD= 9.76) were assessed with the WAIS-IV. Data were analyzed following two independent strategies: A) multiple linear regression with the aim of maintaining the scale's factorial structure; and B) correlational analyses between scores on all WAIS-IV subtests and Full-Scale IQ (FSIQ). Validity of the resulting short-forms was also analyzed. Three short-forms were developed: Proposal A from strategy A (Vocabulary, Block Design, Arithmetic and Symbol Search), Proposal B1 (Vocabulary, Block Design, Digit Span and Visual Puzzles) and Proposal B2 (Vocabulary and Block Design), from strategy B. All three short-forms showed a strong and significant correlation with the FSIQ and were considered psychometrically acceptable. Arguments in favor of Proposal B1 are discussed. Assessing FSIQ with these short-forms will be useful for avoiding long assessment procedures in a population characterized by high fatigability.

White matter integrity changes and neurocognitive functioning in adult-late onset DM1: a follow-up DTI study.

Myotonic Dystrophy Type 1 (DM1) is a multisystemic disease that affects gray and white matter (WM) tissues. WM changes in DM1 include increased hyperintensities and altered tract integrity distributed in a widespread manner. However, the precise temporal and spatial progression of the changes are yet undetermined. MRI data were acquired from 8 adult- and late-onset DM1 patients and 10 healthy controls (HC) at two different timepoints over 9.06 years. Fractional anisotropy (FA) and mean diffusivity (MD) variations were assessed with Tract-Based Spatial Statistics. Transversal and longitudinal intra- and intergroup analyses were conducted, along with correlation analyses with clinical and neuropsychological data. At baseline, reduced FA and increased MD values were found in patients in the uncinate, anterior-thalamic, fronto-occipital, and longitudinal tracts. At follow-up, the WM disconnection was shown to have spread from the frontal part to the rest of the tracts in the brain. Furthermore, WM lesion burden was negatively correlated with FA values, while visuo-construction and intellectual functioning were positively correlated with global and regional FA values at follow-up. DM1 patients showed a pronounced WM integrity loss over time compared to HC, with a neurodegeneration pattern that suggests a progressive anterior-posterior disconnection. The visuo-construction domain stands out as the most sensitive neuropsychological measure for WM microstructural impairment.

A Validated WISC-V Short-Form to Estimate Intellectual Functioning in Very Preterm Children at Early School Age.

Very preterm children (gestational age < 32 weeks) frequently show neurodevelopmental difficulties (Inattention/dysexecutiveness) throughout their life-stages. A scarcity of resources, along with this population's cognitive vulnerability, makes the neuropsychological evaluation of these children both complicated and time-consuming. This study aimed to develop a specific and valid Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V) short-form to estimate intellectual functioning in this population. Eighty-four very preterm children (39 female; mean age = 6.50; SD: 0.06) were assessed with the WISC-V. Short-forms were developed following two independent strategies: a) multiple linear regressions for each index; b) correlational analyses between scores on all administered subtests and Full-Scale IQ. Validity of short-forms was analyzed. A short-form (Vocabulary, Matrix Reasoning, Picture Span, and Symbol Search) that satisfied 2/3 validation criteria was proposed. This validated short-form could facilitate the identification of cognitive difficulties in very preterm children, so that they could benefit from early care and support services, avoiding long assessment procedures.

Small for Gestational Age Moderate to Late Preterm Children: A Neuropsychological Follow-up.

Determine whether SGA constitutes a neurodevelopmental risk-factor of MLP, exploring if potential developmental difficulties at toddlerhood persist and are related to school-age performance. 109 SGA and 109 adequate for gestational age MLP children were evaluated at 2 and at 6.5 y.o. SGA children obtained poorer results in several areas at both timepoints; and their development at toddlerhood strongly correlated with only some results at school-age. SGA confers vulnerability to MLP, evolving from global/unspecific difficulties in toddlerhood to a domain-specific profile (attentional/dysexecutive) at 6.5. Findings claim the need for neuropsychological follow-up in MLP to identify emerging difficulties.

Age-related cognitive decline in myotonic dystrophy type 1: An 11-year longitudinal follow-up study.

BACKGROUND: Myotonic dystrophy type 1 (DM1) is an inherited multi-systemic disease involving the central nervous system (CNS) and is consequently characterized by a range of cognitive impairments. However, whether this cognitive profile progresses over time is still a matter of debate. The aim of this study was to longitudinally assess a DM1 sample, in order to compare, for the first time, this progression with that of a control group. Clinical and socio-demographic predictive factors potentially implicated in this possible decline are analysed. METHOD: Seventy-five DM1 patients with childhood, juvenile, adult, and late-onset, and 54 control participants were re-assessed in an 11-year follow-up with a comprehensive neuropsychological battery. The analyses employed were mixed ANOVA for repeated measures to test intergroup comparisons over time and multiple linear regression for predictive variable analysis. RESULTS: Myotonic dystrophy type 1 patients significantly worsened in visuospatial/visuoconstructive abilities and visual memory compared with controls. Multiple linear regression revealed that progression of cognitive impairment measured by copy of the Rey-Osterrieth complex figure was predicted by muscular impairment, whilst on the block design test age predicted the change with a cut-off at 31 years of age. DISCUSSION: A domain-specific progressive cognitive decline was found in DM1, with visuospatial/visuoconstructive abilities showing the greatest vulnerability to the passage of time. In addition to important clinical implications, these results suggest the need for the scientific community to delve deeper into the potential mechanisms underlying early cognitive decline in this population.

Neurodegeneration trajectory in pediatric and adult/late DM1: A follow-up MRI study across a decade.

OBJECTIVE: To characterize the progression of brain structural abnormalities in adults with pediatric and adult/late onset DM1, as well as to examine the potential predictive markers of such progression. METHODS: 21 DM1 patients (pediatric onset: N = 9; adult/late onset: N = 12) and 18 healthy controls (HC) were assessed longitudinally over 9.17 years through brain MRI. Additionally, patients underwent neuropsychological, genetic, and muscular impairment assessment. Inter-group comparisons of total and voxel-level regional brain volume were conducted through Voxel Based Morphometry (VBM); cross-sectionally and longitudinally, analyzing the associations between brain changes and demographic, clinical, and cognitive outcomes. RESULTS: The percentage of GM loss did not significantly differ in any of the groups compared with HC and when assessed independently, adult/late DM1 patients and their HC group suffered a significant loss in WM volume. Regional VBM analyses revealed subcortical GM damage in both DM1 groups, evolving to frontal regions in the pediatric onset patients. Muscular impairment and the outcomes of certain neuropsychological tests were significantly associated with follow-up GM damage, while visuoconstruction, attention, and executive function tests showed sensitivity to WM degeneration over time. INTERPRETATION: Distinct patterns of brain atrophy and its progression over time in pediatric and adult/late onset DM1 patients are suggested. Results indicate a possible neurodevelopmental origin of the brain abnormalities in DM1, along with the possible existence of an additional neurodegenerative process. Fronto-subcortical networks appear to be involved in the disease progression at young adulthood in pediatric onset DM1 patients. The involvement of a multimodal integration network in DM1 is discussed.

Regional brain atrophy in gray and white matter is associated with cognitive impairment in Myotonic Dystrophy type 1.

BACKGROUND: Myotonic Dystrophy type 1 (DM1) is a slowly progressive myopathy characterized by varying multisystemic involvement. Several cerebral features such as brain atrophy, ventricular enlargement, and white matter lesions (WMLs) have frequently been described. The aim of this study is to investigate the structural organization of the brain that defines the disease through multimodal imaging analysis, and to analyze the relation between structural cerebral changes and DM1 clinical and neuropsychological profiles. METHOD: 31 DM1 patients and 57 healthy controls underwent an MRI scan protocol, including T1, T2 and DTI. Global gray matter (GM), global white matter (WM), and voxel-level Voxel Based Morphometry (VBM) and voxel-level microstructural WM abnormalities through Diffusion Tensor Imaging (DTI) were assessed through group comparisons and linear regression analysis with age, degree of muscular impairment (MIRS score), CTG expansion size and neuropsychological outcomes from a comprehensive assessment. RESULTS: Compared with healthy controls, DM1 patients showed a reduction in both global GM and WM volume; and further regional GM decrease in specific primary sensory, multi-sensory and association cortical regions. Fractional anisotropy (FA) was reduced in both total brain and regional analysis, being most marked in frontal, paralimbic, temporal cortex, and subcortical regions. Higher ratings on muscular impairment and longer CTG expansion sizes predicted a greater volume decrease in GM and lower FA values. Age predicted global GM reduction, specifically in parietal regions. At the cognitive level, the DM1 group showed significant negative correlations between IQ estimate, visuoconstructive and executive neuropsychological scores and both global and regional volume decrease, mainly distributed in the frontal, parietal and subcortical regions. CONCLUSIONS: In this study, we describe the structural brain signatures that delineate the involvement of the CNS in DM1. We show that specific sensory and multi-sensory - as well as frontal cortical areas - display potential vulnerability associated with the hypothesized neurodegenerative nature of DM1 brain abnormalities.

Social cognition in myotonic dystrophy type 1: Specific or secondary impairment?

AIMS: The cognitive profile of Myotonic Dystrophy type 1 (DM1) has been described in recent decades. Moreover, DM1 patients show lowered social engagement and difficulties in social-cognitive functions. The aim of the present study is to explore whether social cognition impairment is present in DM1 taking into account the overall cognitive condition. METHOD: 38 patients and a control group paired in age and gender participated in the study. All the participants had an IQ within the normal range. Subjects were administered an abbreviated neuropsychological battery which comprised a facial emotion recognition test (POFA) and Faux Pas Test, as well as a self-report questionnaire on cognitive and affective empathy (TECA). RESULTS: Statistically significant differences were found only for facial emotion recognition (U = 464.0, p = .006) with a moderate effect size (.31), with the controls obtaining a higher score than the patients. Analyzing each emotion separately, DM1 patients scored significantly lower than controls on the recognition of anger and disgust items. Emotion recognition did not correlate with genetic load, but did correlate negatively with age. No differences were found between patients and controls in any of the other variables related to Theory of Mind (ToM) and empathy. CONCLUSION: DM1 does not manifest specific impairments in ToM since difficulties in this area predominantly rely on the cognitive demand of the tasks employed. However, a more basic process such as emotion recognition appears as a core deficit. The role of this deficit as a marker of aging related decline is discussed.