Development of Virtual Reality-based Interventions to Strengthen Cognitive Skillsets Related to Attention Deficit Hyperactivity Disorder (ADHD): A Pilot Phase I and Randomized Controlled Phase II Trial

* INCLUSION CRITERIA: In order to be eligible to participate, an individual must meet all of the following criteria: 1. Children must provide informed assent and parents must provide informed consent to participate in the study. 2. Any sex assigned at birth, or race/ethnicity. 3. Aged between 8 and 16 years of age, including all months leading up to age 17. 4. Meets diagnosis for ADHD, predominately inattentive or combined presentations, or a specified presentation of having prominent symptoms of inattention that are impairing in two or more settings (but not numerous enough to meet a diagnosis of inattentive or combined presentation). 5. Stated willingness to comply with all study procedures and lifestyle considerations and availability for the duration of the study. 6. For the Pilot only: If treated for ADHD with psychostimulants, willing to withdraw medication three days prior to baseline assessments and to stay off medication until completion of the post-intervention assessment. Not receiving any other psychotropic medication for at least 30 days prior to baseline assessment. EXCLUSION CRITERIA: An individual who meets any of the following criteria will be excluded from participation in this study: 1. Cognitively not capable of performing study procedures. Indications of a lack of cognitive capacity could include a known IQ under 70, or a history from the screening interview that implies global intellectual disabilities (e.g., placement in a school for children with intellectual disability etc.) 2. History of severe migraines, vertigo, epilepsy (with the exception of febrile seizures), or serious balance disorders. 3. Impairments in uncorrected visual acuity that would interfere with engagement with the VR training. 4. Known to be pregnant. 5. Psychotic disorders (including schizophrenia, psychosis not otherwise specified), current substance dependence. Other psychiatric disorders elicited on the interview are not considered exclusionary provided that ADHD is considered to be one of the dominant sources of impairment for the child. 6. Considered a suicide risk as determined during the clinical interview at baseline. 7. Any other medical or psychiatric condition that in the opinion of the PI may confound study data/assessments (e.g., limitations in mobility that would render the VR headset unusable). 8. Recent (within three months) treatment with other cognitive training interventions (e.g., Cogmed) for ADHD. 9. The VR equipment produces excessive discomfort to the child in the opinion of the PI (e.g., including participants with small interpupillary distances (IPD) that are only able to see blurry images on the VR headset, or children showing signs of undue neck and upper body strain or fatigue while trying the headset). 10. For the main trial only: Certain psychotropic medications classes that are likely to interfere with the completion of the intervention are exclusionary: antipsychotics, mood stabilizers (lithium, valproate, lamotrigine, gabapentin). Medications for ADHD will not be considered as exclusionary. This includes psychostimulants, atomoxetine, alpha 2 adrenergic agonists. Antidepressant and anxiolytic medication will also not be exclusionary if they are deemed not to not interfere with study procedures 11. For the main trial only: Prior use of Floreo s products including but not limited to their ADHD cognitive training application.