An observational study in Down Syndrome (Trisomy 21) and Fragile X Syndrome (FXS), sponsored by Hospices Civils de Lyon. Recruiting at 1 site in France. Open to participants aged 3 Years to 29 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-05.
Sponsored by Hospices Civils de Lyon · Observational
This project studies the neurocognitive basis of trust adjustment in intellectual disability (ID), a source of significant vulnerability for these patients, focusing on two target populations chosen for their specific social characteristics: people with Down syndrome, who are often described as being hypersocial, and people with Fragile X syndrome, who are often characterized by a completely opposite social behaviour profile, with a withdrawn attitude and significant social anxiety.
The three different types of mechanisms that contribute to the adjustment of interpersonal trust: affective evaluation, trait attribution, and epistemic evaluation of informants, will be studied. Affective evaluation processes recruit subcortical structures such as the amygdala and assess potential social threats in the environment. The second mechanism for selecting whom to trust consists of forming a representation of a person's dispositions, such as benevolence and competence (also known as traits), and using it to predict that person's future behaviour. Trait attribution processes recruit a cortico-cerebellar network comprising the mPFC, CRUS I and posterior lobule VI. The third mechanism, called epistemic vigilance, allows to adjust our trust in what others communicate to us. This mechanism involves linking the assessment of the reliability of individuals who communicate (based on their benevolence and competence) with the reliability of the communicated information. Epistemic assessment involves frontal areas and areas associated with the representation of mental states in order to enable the evaluation of the truthfulness of the communicated information. All of these mechanisms become functional very early on, before a child's sixth birthday. There are reasons to expect that several of these central mechanisms supporting selective trust will behave atypically in intellectual disability.
438 studies on the registry are indexed under Down Syndrome; 99 are open to participants now.
This study's planned enrollment of 112 is below the median of 158 across 145 observational studies indexed under Down Syndrome.
Browse Down Syndrome studies →Hospices Civils de Lyon is the lead sponsor of 1,866 studies on the registry; 448 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Four groups of participants will be included in the study:
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Group of Down Syndrom patients
Group of X-Fragile Syndrome
Group of chronological age-matched control
Group of mental age-matched control
Exclusion Criteria:
Groups of Down Syndrom and X-Fragiles patients
Regarding the neuroimaging (MRI) study:
Groups of typical development persons (chronological age-matched and mental age-matched)
Regarding the neuroimaging (MRI) study (only for chronological age-matched group):
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients aged 13 to 29 years old with a confirmed diagnosis of Down Syndrome
Other: Confidence adjustment assessment · Other: clinical assessment · Other: Cognitive assessment · Other: Executive function assessment · Other: Sociability assessment · Other: Brain MRI (structural and functional)
Patients aged 13 to 29 years old with a confirmed diagnosis of Fragile X Syndrome
Other: Confidence adjustment assessment · Other: clinical assessment · Other: Cognitive assessment · Other: Executive function assessment · Other: Sociability assessment · Other: Brain MRI (structural and functional)
Persons aged 13 to 29 years old with typical development
Other: Confidence adjustment assessment · Other: clinical assessment · Other: Cognitive assessment · Other: Executive function assessment · Other: Sociability assessment · Other: Brain MRI (structural and functional)
Persons aged 3 to 9 years old with typical development
Other: Confidence adjustment assessment · Other: clinical assessment · Other: Cognitive assessment · Other: Executive function assessment · Other: Sociability assessment
Interpersonal trust assessment including a series of behavioural and eye-tracking studies (Paradigm 1 : Forming impressions using facial cues; Paradigm 2 : Forming impressions using behaviors) and assessment of epistemic trust (Paradigm 3 : assessing informants, Paradigm 4 : vigilance towards deception), will be performed at visit V1.
Clinical assessment including Medical history, developmental trajectory, epilepsy history, clinical examination, presence of autism spectrum disorder, presence of cardiopathy, will be performed at visit V1.
Cognitive assessment including Raven Matrix, Wechsler Scale (WISC-V or WAIS IV), Vineland Adaptive Behavior Scale II, PPVT5, EVT3, will be performed at visit V1.
Executive function assessment including Laby 5-12 test, day/night Test, Questionnaire BRIEF-2, will be performed at visit V1.
Sociability assessment including Social Responsiveness Scale 2, Revised Preschool Anxiety Scale, two eye-tracking tasks (social scenes and social preference), Perception bias task, Distance adjustment task, Social motivation tasks, Examiner's assistance task, will be performed at visit V1.
Optional brain MRI acquisition (structural and functional) will be performed at ancillary visit
Error rate (percentage) for each of the four paradigms.
Paradigm 1 /Facial trait assessment : Error rates for each condition (3 levels of difficulty) and 2 types of questions (traits/behaviours) Paradigm 2 / Behaviour assessment: Error rates for each of the three conditions (traits-to-behaviour, behaviour-to-traits, and behaviour-to-behaviour) Paradigm 3/ Assessing informants : error rates for each type of informant Paradigm 4 / Vigilance towards deception: Error rates concerning the location of the pompom, for each of the four conditions: baseline, benevolence, malicious intent, and explicit falsehood of the character.
Time frame: Day 1
Response time (millisecond) for two of the four paradigms.
Paradigm 1 / Facial trait assessment: Analysis of response times (in milliseconds) for each condition (3 levels of difficulty (easy/moderate/difficult) and 2 types of questions (traits/behaviours) obtained using Presentation® software. Paradigm 2 / Behaviour assessment: Analysis of response times (in milliseconds) for each of the three conditions (traits-to-behaviour, behaviour-to-traits, and behaviour-to-behaviour) using Presentation software.
Time frame: Day 1
Analysis of visual strategies for eye-tracking experiments.
Paradigm1 / Facial trait assessment: Observation time on different areas of interest (AOI eyes, AOI nose-mouth) obtained using the eye tracker (Tobii ProLab). Paradigm 2 / Behaviour assessment: measurement of time spent on each region of interest corresponding to the task images (in milliseconds) obtained using the eye tracker (Tobii ProLab)
Time frame: Day 1
Presence of epilepsy (Yes/No)
Data from clinical examination and medical file
Time frame: Day 1
Developmental trajectory
* Age at head control acquisition in months, * Age at sitting alone in months, * Age at walking alone in months, * Age at running in months, * Age at climbing stairs alternately in months, * Age at voluntary grasping an object in months, * Age at thumb-index pinch in months, * Age at first words utterance in months, * Age at two words association in months, * Age at first sentences production in months, * Age at first responsive smiles in months, * Age at joint attention acquisition in months, * Age at fear of unfamiliar person in months, * Age at pretend to play in month, * Age at daytime toilet training in months, * Age at night-time toilet training in months,
Time frame: Day 1
Mental age, in years, [4-12 years] assessed with the Raven's Progressive Matrices test
Cognitive assessment
Time frame: Day 1
Presence of an associated autism spectrum disorder (Yes/No)
Data from clinical examination and medical file
Time frame: Day 1
Existence of cardiac malformation (Yes/No).
Data from clinical examination and medical file
Time frame: Day 1
Total IQ [40-160] from Wechsler scales adapted for age (WISC-V for patients aged above 6 years, and WAIS-IV for patients above 16 years)
Cognitive assessment assessing the intelligence quotient of the participant. Intellectually disabled patients have an IQ below 70.
Time frame: Day 1
Global score [20 - 160] and standard scores [20 - 160] for the areas of adaptive skills (communication, daily life, socialisation, and motor skills) with the VABS2.
Adaptive assessment based on interview with the parents of the patient. A score below 70 is considered as impaired.
Time frame: Day 1
Receptive and expressive lexical age [2-19] (in years) with PPVT5 and EVT3 tests respectively
Language assessment. These two tests allow the assessment of receptive and expressive language level (lexical age).
Time frame: Day 1
Z scores [-5; +5] for the General Error Index, the Delay Aversion Index, and the Inhibition Index with Laby 5-12 test.
Executive function assessment (planification) - The Z-score is used to assess a child's performance in relation to that of a normative group. A Z-score \< -2 means a clinically relevant impairment
Time frame: Day 1
Score [0 -16] for the control condition and for the test condition with the Day/night test.
Executive function assessment (inhibition) A score ≤ 8 indicates a weak performance and a potential weakness in executive functions
Time frame: Day 1
T-scores [0 -100] for the overall executive score with the BRIEF-2 questionnaire
Executive function assessment A T-score \> 65 means clinically relevant executive difficulties.
Time frame: Day 1
Total T scores [30 - 90] with SRS-2 scale
Sociability assessment A T-score \> 76 indicates severe social difficulties.
Time frame: Day 1
Total score [0 -140] with the Liebowitz Social Anxiety Scale for Children and Adolescents
Sociability assessment A score above 70 indicates a severe social anxiety.
Time frame: Day 1
Observation time (in seconds) on social AOIs (Areas of Interest) and non-social AOIs for Social scene task in eye-tracking.
Sociability assessment
Time frame: Day 1
Proportion of fixation time on the social vs non-social AOI for Social preference task in eye-tracking
Sociability assessment
Time frame: Day 1
Latency, in milliseconds, of the first fixation on each type of AOI for Social preference task in eye-tracking.
Sociability assessment
Time frame: Day 1
Error rate, in percentage, for the Perception bias task
Sociability assessment
Time frame: Day 1
Score [1-6] for the Distance adjustment task
Sociability assessment The score is determined according to the distance at which the participant sits compared to the position of the unknown person
Time frame: Day 1
Social motivation score [1-6] for the social motivation task
Sociability assessment
Time frame: Day 1
Score [0-12] reflecting the willingness of the participant to help the examiner for the Examiner's assistance task
Sociability assessment The score will reflect if the participant does it spontaneously, or only one suggested, or only once explicitly mentioned or not al all.
Time frame: Day 1
Presence (Yes/No) of cerebral abnormalities from neuroimaging data.
* Presence of white matter abnormality (Yes/No) * Presence of corpus callosum abnormality (Yes/no) * Presence of cerebral atrophy (Yes/No)
Time frame: Day 2
Brain volume (mm3) and surfacic analysis (in mm) using Freesurfer software on 3DT1 morphometric data. Freesurfer analysis
Neuroimaging analysis. Brain volume and surfacic analysis will be performed using the Freesurfer software, allowing to compare between the 3 groups of participants (Fragile X, DS and controls).
Time frame: Day 2
Functional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivity using Track-Based Spatial Statistics (TBSS) software.
Neuroimaging diffusion data analysis.
Time frame: Day 2
Brain regions (clusters) activation (BOLD signal) during the assessment of the character's reliability.
Neuroimaging functional MRI analysis. The BOLD signal reflects local and transient variations in the amount of oxygen carried by haemoglobin as a function of neuronal activity in the brain. fMRI data will be analyzed using FSL software.
Time frame: Day 2
Started Jul 2026 (actual). Primary completion is estimated for Jan 2030, 42 months after the start.
Of 40 non-industry observational studies under Down Syndrome, half reached primary completion within 31 months of starting (the median), counting those still running; a quarter within 23 and three quarters within 71. This study's planned 42 months is above that.
Counting every sponsor, half of 55 studies reached it within 34 months; a quarter within 19 and three quarters within 80.
How these figures are worked out, and which studies are left out of them.
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