Software Treatment for Actively Reducing Severity of ADHD in Adults (STARS ADHD Adult)

Inclusion Criteria: 1. Adults 18 years and older 2. Diagnosis of ADHD combined or inattentive type, according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) as confirmed by Mini International Neuropsychiatric Interview (MINI) for Attention - Deficit / Hyperactivity Disorders Studies (Adult) 7.0.2 3. Stably on or off ADHD medications for ≥4 weeks prior to study enrollment and throughout the primary 6-week study 4. Stably on or off psychoactive medications for ≥4 weeks prior to study enrollment and throughout the 6-week study 5. Baseline visit score on the ADHD-RS-IV of ≥ 24 6. Baseline visit score on the TOVA-ACS score ≤ -1.8 7. Estimated IQ score ≥80 as assessed by the Kaufmann Brief Intelligence Test, Second Edition (KBIT-II) 8. Access to and self-report of ability to connect wireless devices to a functional wireless network 9. Ability to follow written and verbal instructions (English) as assessed by the PI and/or study coordinator 10. Able to comply with all testing and study requirements 11. Completion of informed consent form Exclusion Criteria: 1. Current controlled or uncontrolled, comorbid psychiatric diagnosis with significant symptoms that in the opinion of the Investigator may confound study data/assessments. 2. Suicidality assessed using the Columbia-Suicide Severity Rating Scale (C-SSRS) 3. Motor condition (e.g., physical deformity of the hands/arms) that prevents game playing as reported by the participant or observed by the Investigator. 4. History of moderate or severe substance use disorder within the last 12 months prior to informed consent 5. History of seizures (excluding febrile seizures), significant tics, or a current diagnosis of Tourette's Disorder. 6. Known sensitivity to playing video games, such as photo-sensitive epilepsy, light-headedness, dizziness, nausea, or motion sickness. 7. Color blindness as detected by Ishihara Color Blindness Test 8. Positive urine drug screen 9. Current or recent (3 months prior to screening) history of heavy smoking defined as the equivalent of greater than or equal to a pack of cigarettes a day 10. Any other medical condition that in the opinion of the Investigator may confound study data/assessments. 11. Participation in a clinical trial within 3 months prior to screening. 12. Previous exposure to Akili products within the 6 months prior to study enrollment 13. Plans to initiate new concomitant medications during the primary study, except for common over the counter (OTC) (e.g., ibuprofen, acetaminophen) and prescription medications (e.g., antibiotics) for minor transient ailments. 14. Planned initiation of, or significant changes in frequency, of non-pharmacological behavioral therapy during the primary study 15. Planned initiation of, or significant changes in frequency of, non-pharmacological trainings with the aim to improve cognition by means of game or app-based cognitive trainings or neurofeedback, during the primary study