Neuropsychological Evaluation in Intellectual Disability

The goal of this observational study is to evaluate the acceptability ofpatients with trisomy 21 (T21) to perform the full battery of ENDI neurospychological tests and each of the subsets. In this study, three types of population will be recruted : normotypic volunteers, patients with Intellectual Disability and patients T21carriers. This study is separated into 2 phases : * A the preliminary phase : this phase will be used to evaluate subtest design, ergonomics and understanding of instructions, and to identify any malfunctions. The observations gathered will enable the principal investigator to refine the digital design of the battery in collaboration with the publishing company. In this phase, normotypical volunteers and patients with intellectual disabilities will be recruted to perform ENDI test battery. * A main phase : this phase will enable to answer to the main objective. in this phase, patients with Trisomy 21 aged between 25 and 65 will be recruted to perform ENDI test battery.