The present project is to identify the relationship between ADHD and the metabolites of tryptophan.

Because attention deficit hyperactivity disorder (ADHD) is an early onset and long-term impairing disorder with tremendous impact on individuals, families, and societies, detection and diagnosis are very important for ADHD. According to investigators previous work, participants with ADHD have executive dysfunction. Previous studies show that tryptophan is associated with cognitive problems in participants. Analyzing differences in tryptophan metabolites (Indolepropionic acid [IPA], indoleacetic acid [IAA], and kynurenic acid [KYNA]) between participants with ADHD and healthy controls could provide insight into underlying disease pathology of cognitive deficits. In this one-year project, investigators will perform an analysis of tryptophan metabolites in serum to identify potential biomarkers for the executive dysfunction of ADHD.

The ADHD group

1. Inclusion Criteria

   Patients with ADHD are eligible to be included in this study only if they meet all of the following criteria:

   1. Patients will be outpatients who are between 7 and 18 years of age.
   2. Patients must have ADHD that meet the Diagnostic and Statistical Manual of Mental disorders, 5th edition (DSM-V) disease diagnostic criteria assessed by the investigator's clinical evaluation, as well as confirmed by the Chinese version of the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiological Version (K-SADS-E).
   3. Patients must have a Clinical Global Impressions-ADHD-Severity (CGI-ADHD-S) score > 4 at baseline.
   4. Patients must be psychotropic drug-naïve. Patients will be considered to be drug-naïve if they have never received medications specifically to treat ADHD.
   5. Patients and parents (or legal representative) must have a degree of understanding sufficient to be able to communicate suitably with the investigator.
   6. Patients must be of normal intelligence in the judgment of the investigator. Normal intelligence is defined as achieving a score of 80 or more when IQ testing is administrated.
   7. Patients must have been judged by the investigator to be reliable to keep appointments for clinic visits and all tests, including neuropsychological testing and venipunctures.

2. Exclusion Criteria

Patients will be excluded from the study if they meet any of the following criteria:

1. Patients with current or past history of schizophrenia, schizoaffective Disorder, organic psychosis, bipolar I or II disorder, autism, or autism spectrum disorder. Other comorbid psychiatric disorders are not excluded if the ADHD symptoms are the primary source of impairment for the patient.
2. Patients with a history of any seizure disorder (other than febrile convulsion) or patients who are taking anticonvulsants for seizure control.
3. Patients have been at serious suicidal risk, determined by the investigator.
4. Patients with a history of alcohol or drug abuse within the past 3 months, or who are currently using alcohol, drugs of abuse, or any described or over-the-counter medication in a manner that the investigator considers indicative of abuse.
5. Patients with cardiovascular disease or other conditions that could be aggravated by an increased heart rate or increased blood pressure.
6. Patients who are likely to need Chinese medicine or health-food supplements that have central nervous system activity.

120 drug-naïve patients with ADHD, aged 7 to 18 years, will be enrolled. Another 120 healthy participants with matched age and sex will be enrolled in the control group.