Genetic, Brain Structure, and Environmental Effects on ADHD

* INCLUSION CRITERIA FOR ALL PARTICIPANTS: Three or more years of age with no upper limit for age at time of enrollment. The lower limit of 3 years of age is chosen as it is difficult to diagnose ADHD below this age, but the diagnosis can be reliably made from age 3 onwards. As this study examines the developmental trajectories of ADHD into adulthood, no upper age limit has been set. INCLUSION CRITERIA FOR CLINICAL POPULATIONS: Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) defined ADHD. The DSM-IV diagnosis of ADHD will be based on the Parent Diagnostic Interview for Children and Adolescents in participants 18 years or age and younger and the Structured clinical interview for the Diagnosis of DSM Disorders for participants above 18 years of age. We include all forms of ADHD in DSM-5 (i.e. combined, predominately hyperactive/impulsive, predominately inattentive and other specified presentations). ADHD is rarely found in isolation and comorbidity is common. Thus the protocol will include individuals with ADHD and the following disorders: oppositional defiant disorder, conduct disorder, anxiety disorders (generalized anxiety, specific phobias), tic disorders, mood disorders (dysthymia, depression); specific learning disabilities and disruptive mood dysregulation disorder. We will also include families where there is a incidence of \>30% of ADHD in first, second and third degree relatives. This level is chosen as it is well above the incidence rate of ADHD in the general population (\~5-7%). Additional inclusion criteria are families where the proband has at least one sibling and only one or neither parent is affected. In studying the acute effects of treatment we will include all participants with ADHD who are starting psychostimulant medications for the first time (all psychostimulant preparations are included). We will also include participants with ADHD who are receiving behavioral management for ADHD for the first time. INCLUSIONS CRITERIA FOR THE FAMILY STUDY: We will also include families where there is a incidence of \>30% of ADHD in first, second and third degree relatives. This level is chosen as it is well above the incidence rate of ADHD in the general population (\~5-7%). Additional inclusion criteria are families where the proband has at least one sibling and only one or neither parent is affected. We have already identified families of our currently enrolled probands in which at least 4 other first, second or third degree relatives have a current diagnosis of ADHD or had this diagnosis in childhood (and have a similar number of unaffected relatives). We will recruit further families with a similar density of individual affected by ADHD. EXCLUSION CRITERIA FOR ALL PARTICIPANTS: Full scale IQ of less than 70. Below this level a child is considered to have global intellectual disability (classified in DSM-IVR as mental retardation). By definition this means the individual cannot be considered to be a healthy control . While many individual with IQ below 70 have symptoms of ADHD, the diagnosis is complicated by problems in assessing attentional abilities. Finally, there are often issues around the ability to give informed consent in adults with global intellectual disability. Birth before 32 weeks of gestation. Premature birth can have a profound effect on brain function and structure. Presence or history of medical conditions known to affect cerebral anatomy (eg epilepsy, history of stroke). Genetic syndromes which are associated with well-established alterations of gross cerebral structure- such as NF1, tuberous sclerosis and some forms of epilepsy. Children with known microdeletion syndromes will not be excluded provided (1) the syndrome is not known to be associated with alteration of cerebral anatomy (detectable on current clinical MRI sequences) and (2) other exclusionary criteria do not apply such as global intellectual impairment (defined in this protocol as IQ above 70). Data from these individuals with microdeletion syndromes will not however be included in GWAS due to analytic complications. Dental braces (as these distort the MRI image). Metal in the body or other contraindications for MRI scanning. For females who have reached menarche and have not yet past menopause: pregnancy or inability or unwillingness to undergo pregnancy testing (for MRI safety). For participants 60 years or older. Folstein mini mental state examination score of 26 or greater. This is a widely accepted screening test for dementia. ADDITIONAL EXCLUSION CRITERIA FOR HEALTHY VOLUNTEERS ONLY: Presence of any DSM-IV psychiatric disorder in the subject or current use of psychiatric medication. ADDITIONAL EXCLUSION CRITERIA FOR THE CLINICAL POPULATION ONLY: Some neuropsychiatric disorders are either so rare or associated with such profound alterations of brains structure and function that they will be excluded. This includes psychotic disorders (including schizophrenia, psychosis NOS) bipolar affective disorder; autism, substance dependence; dementia.