Neuropsychological Evaluation in Intellectual Disability (ENDI)

Inclusion Criteria: Preliminary phase: 1. The inclusion criteria for the group of people with intellectual disabilities are as follows: * Participant who has received full information on the organization of the research and has not objected to his or her participation and to the use of his or her data. * Legal guardian of the participant, if applicable, who has received full information on the organization of the research and has not objected to participation and use of his/her data. * Age at inclusion: ≥ 25 and ≤ 65 years * Notion of intellectual disability in medical records * Access to the oral language of the participant with an intellectual disability: the subject's speech must be comprehensible to the evaluator and the subject must be able to understand simple statements. It is not possible to use an oral comprehension test (e.g. Token test by Renzi \& Vignolo, 1962), as the norms achieved in healthy subjects would exclude almost all patients with intellectual disabilities, who have more limited language skills. * Enrolled in or benefiting from a social security scheme. 2. The inclusion criteria for the normotypic group are as follows: * Participant having received full information on the organization of the research and not having objected to his or her participation and to the use of his or her data. * Age at inclusion: ≥ 25 and ≤ 65 years * Affiliation with a social security scheme or beneficiary of such a scheme Main phase: Inclusion criteria are as follows: * Participant with T21 who has received full information on the organization of the research and has not objected to participation and use of his/her data * Legal guardian of the participant with T21, where applicable, who has received full information on the organization of the research and has not objected to his or her participation and the use of his or her data. * Person with trisomy 21 * Age at inclusion: ≥ 25 and ≤ 65 years * Access to the oral language of the participant with T21: the subject's speech must be comprehensible to the evaluator and the subject must be able to understand simple statements. It is not possible to use an oral comprehension test (e.g. Token test by Renzi \& Vignolo, 1962), as the norms achieved in healthy subjects would exclude almost all patients with intellectual disabilities, who have more limited language skills. * Membership of a social security scheme or beneficiary of such a scheme Exclusion Criteria for both phases of the study are as follows: * Disabling motor and/or sensory impairments preventing completion of the tests * Insufficient command of the French language to complete the tests * Severe general medical condition or alcoholism (habitual consumption of 3 drinks/day or history of alcohol withdrawal) * History of stroke, severe head trauma, or cancer * Change in long-term medication within 8 weeks prior to evaluation * Refusal to participate by the subject and/or legal representative * Individuals referred to in Articles L.1121-5 to L.1121-7 of the French Public Health Code: * Pregnant women, women in labor, or breastfeeding mothers * Individuals deprived of liberty by judicial or administrative decision * Individuals undergoing psychiatric treatment under Article L.3213-1 of the French Public Health Code