Neuro-Nutrition to Support Physiological Function and Cognitive Skills in People With Down Syndrome, Autism Spectrum Disorder, and ADHD

Inclusion Criteria: * Age 2-35 years at enrollment. * Clinical diagnosis of Down syndrome (DS), Autism Spectrum Disorder (ASD/TEA), or Attention-Deficit/Hyperactivity Disorder (ADHD/TDAH). For DS, written karyotype confirmation; for ASD/ADHD, clinical criteria (DSM) and standardized scales per protocol (e.g., Conners). * Parent/guardian able to provide written informed consent prior to study procedures. * Willingness to comply with the assigned structured diet and/or supplement regimen and study visits. Exclusion Criteria: * Individuals outside 2-35 years or without DS/ASD/ADHD diagnosis. * Healthy volunteers (no target neurodevelopmental condition). * Inability or unwillingness to adhere to the dietary program and/or supplement (the team may request withdrawal for non-adherence as per protocol). * Lack of informed consent from parent/guardian.