Inclusion Criteria:  Giving informed written consent to participate on a voluntary basis.  For the healthy control group:  Men and women aged 18-40 years, who did not report ADHD or any other chronic or psychiatric illness or medical conditions (at most two symptoms of inattention and/or hyperactivity/impulsivity).  For the ADHD group patients:  Men and women aged 18-40 years, who have a diagnosis of ADHD, according to DSM V criteria by a Neurologist. Have a valid prescription for Mixed Amphetamine salts (Attent) or short-acting methylphenidate (Ritalin) for ADHD Withhold medication 72h prior to MRS scan.  Exclusion Criteria:  Exclusion criteria identical for patients and control group:  Subjects with metallic devices that precludemagnetic resonance imaging or any silver part that is not MRI compliant Current presence of any other DSM V psychiatric disorder Significant medical or neurological illness affecting brain function Subjects with any clinically signiﬁcant or unstable medical conditions Use of any psychotropic medication, other than stimulants, in the previous 3 months Pregnant women BMI > 35 History of brain MRI A patient who does not agree that the scan will be decoded by a radiologist A patient who does not agree that in case of an abnormal finding, the imaging results will be forwarded to the attending physician for further clarification Understanding and/or language problems