This study will develop and evaluate a smartphone-based behavioral intervention for adolescents with Attention-Deficit Hyperactive Disorder (ADHD) and smartphone overuse in Hong Kong. The main questions it aims to answer are:
* Can a smartphone-based intervention lower self-reported smartphone dependence and objective smartphone usage?
* Can a smartphone-based intervention lower parent-rated and self-rated ADHD symptoms?
* Are there differences in electroencephalogram (EEG) in the smartphone salient vs smartphone non-salient conditions after intervention?
Adolescent participants will:
* report weekly smartphone use patterns based on app screencap for 12 weeks
* complete online surveys on smartphone dependency and ADHD symptoms for 3 times
* receive 10-minute EEG recordings to gather resting-state EEG data in a natural and relaxing state for 3 times
Parent participants will:
* provide a valid clinical report to confirm the adolescent's diagnosis of ADHD
* complete online surveys to report on the adolescent's smartphone usage and ADHD symptoms for 3 times