Study of the Nutritional, Inflammatory, and Metabolic Endophenotypes of Attention-Deficit/Hyperactivity Disorder (ADHD)

Study of the Nutritional, Inflammatory, and Metabolic Endophenotypes of Attention-Deficit/Hyperactivity Disorder (ADHD)

This study aims to better understand the biological mechanisms involved in attention deficit hyperactivity disorder (ADHD) and to clarify why some children and adolescents respond well to methylphenidate (MPH)-the most commonly prescribed medication-while others do not. Although MPH is effective for many patients, a significant number experience limited benefits or problematic side effects such as appetite loss and sleep difficulties. Recent research suggests that inflammation and oxidative stress in the body may play an important role in ADHD. Some animal studies also indicate that MPH itself might trigger inflammatory processes, but this has never been examined directly in humans.

The main goal of this research is to determine whether children with ADHD show differences in their nutritional, immune, and inflammatory profiles compared to children without ADHD, and whether these biological factors influence symptom severity, digestive problems, and response to treatment. The study also seeks to understand whether MPH has a measurable inflammatory effect in young patients and whether this could be linked to treatment tolerability.

To answer these questions, the study combines several approaches. First, a case-control comparison will examine differences between children/adolescents with ADHD and age- and sex-matched controls. Second, a one-year follow-up of the ADHD group will evaluate changes over time and help identify biological predictors of treatment response and side effects. Finally, a cross-sectional analysis will investigate the role of polyphenols-natural antioxidant compounds found in food-in relation to inflammation, treatment outcomes, and gender differences.

The primary focus is on comparing levels of the inflammatory marker IL-6 between children with ADHD and controls. Secondary objectives include assessing additional inflammatory and immune indicators, nutritional status, gastrointestinal symptoms, ADHD severity, irritability, and MPH tolerability.

By identifying specific inflammatory and immune markers associated with ADHD and treatment response, this study hopes to improve understanding of the disorder and guide more personalized and effective treatment strategies for young patients. It will also provide the first human data on whether psychostimulant medications may have inflammatory effects.

ADHD Group (Cases) - Inclusion Criteria:

• Children or adolescents aged 7 to 17 years.
• Meet DSM-5 diagnostic criteria for Attention-Deficit/Hyperactivity Disorder (ADHD), assessed using the K-SADS interview.
• Currently treated with psychostimulant medication.
• Stabilized on psychostimulant treatment for at least one month prior to inclusion.
• Signed informed consent obtained from parents or legal guardians.
• Assent obtained from the minor participant.
• Affiliation with a national health insurance system.

Control Group (Typically Developing Peers) - Inclusion Criteria:

• Children or adolescents aged 7 to 17 years without any diagnosed mental disorder.
• Age- and sex-matched with the ADHD group.
• Signed informed consent obtained from parents or legal guardians.
• Assent obtained from the minor participant.
• Affiliation with a national health insurance system.

ADHD Group (Cases) - Exclusion Criteria:

• Presence of a progressive neurological disorder, intellectual developmental disorder, or clinically significant suicide risk.
• Presence of an immunological or chronic inflammatory disease.
• Inability to comply with medication-free periods of at least two weeks.
• Absence of parental consent.
• Absence of assent from the minor participant.
• Participation in another clinical study with an ongoing exclusion period.

Control Group (Typically Developing Peers) - Exclusion Criteria:

• Presence of an immunological or chronic inflammatory disease.
• Absence of parental consent.
• Absence of assent from the minor participant.
• Participation in another clinical study with an ongoing exclusion period.