The objectives of this study are to investigate:

1. the effect of methylphenidate on attention;
2. the relations between methylphenidate and inhibition control and working memory;
3. the relations between inhibition control and verbal attention and working memory;
4. the effect of methylphenidate on the changes of neuropsychological functioning and blood pressure.

Attention deficit hyperactivity disorder (ADHD), characterized by inattention, hyperactivity and impulsivity, is an early onset, highly heritable, clinically heterogeneous, long-term impairing disorder with tremendous impact on individuals, families, and societies. It affects 5-10% of school-aged children worldwide (7.5% in Taiwan). Methylphenidate, a stimulant, is effective in treating these patients. Studies in Taiwan show no effect of methylphenidate on blood pressure. There are evidences show that the change of blood pressure was associated with inhibition of impulsive behaviors. Stop Signal Task(SST) is used to assess the improve of inhibition control after methylphenidate response. By using repeated outcome measurements, we anticipate that this study will evaluate the improvement of neuropsychological performances after medication and determinie the association between medication response and neuropsychological functions and vital signs in a Taiwanese sample.

Inclusion Criteria:

The inclusion criteria for the subjects are (1)that subjects have a clinical diagnosis of ADHD defined by the DSM-IV which was made by a full-time board-certificated child psychiatrist; (2)their ages range from 10 to 18 when we conduct the study; (3)their IQ greater than 80; and (4)they are under treatment of methylphenidate.

Exclusion Criteria:

The subjects will be excluded from the study if they currently meet criteria or have a history of the following condition as defined by DSM-IV: Schizophrenia, Schizoaffective Disorder, Organic Psychosis, or Pervasive Developmental Disorder.

We will recruit 60 children and adolescents, aged 10 to 18, who are diagnosed with ADHD at the Department of Psychiatry, National Taiwan University Hospital.