The Neurocognitive Bases of Trust in Intellectual Disability

The Neurocognitive Bases of Trust in Intellectual Disability: Affective Evaluation, Trait Attribution, and Epistemic Vigilance

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people with Fragile X syndrome, who are often characterized by a completely opposite social behaviour profile, with a withdrawn attitude and significant social anxiety.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.

Inclusion Criteria :

Group of Down Syndrom patients

• Complete chromosomal trisomy of the 21st chromosome confirmed by karyotype analysis
• Aged 13 to 29 (chronological age)
• French as their native language
• Having signed an informed consent form and/or whose legal guardians/patient representatives have signed the informed consent form
• Affiliated with the French health insurance system (social security) or whose legal guardians are affiliated with the French health insurance system

Group of X-Fragile Syndrome

• Complete mutation of the FMR1 gene by molecular analysis (more than 200 CGG triplet repeats)
• Aged between 13 and 29 (chronological age)
• Native French speakers
• Having signed an informed consent form and/or whose legal guardians/patient representatives have signed the informed consent form
• Affiliated with the French health insurance system (social security) or whose legal guardians are affiliated with the French health insurance system

Group of chronological age-matched control

• Aged between 13 and 29
• Native French speakers.
• Having signed an informed consent form and/or whose legal guardians/patient representatives have signed the informed consent form
• Affiliated with the French health insurance system (social security) or whose legal guardians are affiliated with the French health insurance system

Group of mental age-matched control

• Aged between 3 and 9
• Native French speakers.
• Whose legal guardians/patient representatives have signed the informed consent form
• Affiliated with the French health insurance system (social security) or whose legal guardians are affiliated with the French health insurance system

Exclusion Criteria:

Groups of Down Syndrom and X-Fragiles patients

• Inability to understand tasks
• Significant brain malformation
• Uncontrolled epilepsy
• Significant hearing impairment
• Uncorrected visual impairment
• Refusal of the subject and/or legal guardians/representative of the subject to be informed of any abnormalities detected during the neuropsychological assessment.
• Subject participating in another interventional study with an exclusion period still ongoing at the time of pre-inclusion.

Regarding the neuroimaging (MRI) study:

• Having a contraindication to MRI examination (people using a pacemaker or insulin pump, people with metal prostheses or intracerebral clips, people with metal fragments in their eyes, as well as claustrophobic subjects). A comprehensive list of contraindications is provided in Appendix 5.
• Inability to perform the MRI without anaesthesia.
• Refusal by the subject and/or those exercising parental authority/the subject's representative to be informed of any abnormalities detected during the MRI.

Groups of typical development persons (chronological age-matched and mental age-matched)

• Known acquired neurological disorders, including epilepsy.
• History of head trauma requiring hospitalisation.
• Known psychiatric disorders.
• Birth complications requiring admission to a neonatal intensive care unit or prematurity of less than 35 weeks.
• Ongoing treatment with drugs affecting the central nervous system.
• Significant hearing impairment
• Uncorrected visual impairment
• Repeating a school year
• Learning disorders requiring rehabilitation (speech therapy, psychomotor therapy or orthoptics) for more than one year.
• Refusal of the subject and/or legal guardians/representative of the subject to be informed of any abnormalities detected during the neuropsychological assessment.
• Subject participating in another interventional study with an exclusion period still ongoing at the time of pre-inclusion.

Regarding the neuroimaging (MRI) study (only for chronological age-matched group):

• Having a contraindication to MRI examination (people using a pacemaker or insulin pump, people with metal prostheses or intracerebral clips, people with metal fragments in their eyes, as well as claustrophobic subjects). A comprehensive list of contraindications is provided in Appendix 5.
• Inability to perform the MRI without anaesthesia.
• Refusal by the subject and/or those exercising parental authority/the subject's representative to be informed of any abnormalities detected during the MRI.