Omega-3 Fatty Acids Supplementation in ADHD

Inclusion Criteria: Participants between ages 6 and 12 years who: 1. have been clinically diagnosed with ADHD by a physician 2. meet the criteria of ADHD-Inattention, ADHD-Hyperactivity-Impulsivity, or ADHD-Combined type as determined by the SNAP-IV (Swanson, 1992) 3. are willing to participate in a randomized, double-blind, placebo-controlled trial, complete with written, informed parental consent, 4. are on stable dosage of methylphenidate treatment before the start of the study 5. are able to speak English or German Exclusion Criteria: 1. Participants who are younger than 6 years old or older than 12 years old 2. Those who have not been clinically diagnosed with ADHD by a physician 3. Those who did not meet the criteria of ADHD-Inattention, ADHD-Hyperactivity-Impulsivity, or ADHD-Combined type as determined by the SNAP-IV (Swanson, 1992) 4. Those without written parental consent 5. Those with brain pathology such as serious head injury, epilepsy, and intellectual disability (IQ \< 70) 6. Those with titrated dosage of methylphenidate before the start of the study 7. Those on neurofeedback training, and/or psychosocial intervention addressing attention problems 8. Those with known hypersensitivity to the IMP under investigation 9. Those who are unable to read and understand the parent/participant information 10. Those receiving medications other than methylphenidate