Participants were recruited through local postings and outreach activities conducted in the greater metropolitan areas of Baltimore, Boston, Honolulu, Los Angeles, New Haven, New York, Sacramento, and San Diego. Participants were excluded if there was a reported history of major developmental, psychiatric, or neurological disorders, brain injury, prematurity (i.e., born at less than 36 weeks gestational age), exposure to illicit drugs or alcohol prenatally for more than one trimester, history of head trauma with loss of consciousness for more than 30 minutes, or other medical conditions that could affect development.
Individuals with contraindications for MRI studies (such as dental braces, metallic or electronic implants, claustrophobia, or pregnancy) were also excluded from participating.
Individuals with identified or suspected learning disability or ADHD were not excluded since these syndromes are fairly common in pediatric populations.
The PING Study Demographics and Child Health History Questionnaire was completed by parents or guardians of the participants (participants age 18 to 20.9 were given a self-report version of this questionnaire). The questionnaire assessed basic medical, developmental, and behavioral history, as well as family history of medical and neuropsychiatric disorders, including substance abuse.
Cognitive assessments for the PING project are conducted using the NIH Toolbox for Cognition. The purpose of the Toolbox is to briefly and comprehensively index mental abilities of individuals in cognitive tasks. The Cognitive Toolbox applies the following instruments to index their respective cognitive sub-domains:
For more detailed information on the NIH Toolbox for Cognition, please visit their website at http://www.nihtoolbox.org/.
Social-Emotional and Substance Use Assessments
In a subset of participants a limited number of additional assessments of social and emotional functions and substance exposure were acquired through the PhenX Rising project. More information about the PhenX Toolkit and PhenX Rising is available at https://www.phenxtoolkit.org.