Lange, Anne-Mette et al. Journal of the American Academy of Child & Adolescent Psychiatry , Published online June 2018

This multi-centre randomised controlled trial found that parent training was superior to treatment as usual for parent rated ADHD symptoms, improving parent self-efficacy and reducing perceived family stress.   Effects persisted until 36 weeks following the intervention.  Interestingly, there were no differences between treatment and control groups in teacher ratings or direct observation of ADHD symptoms or of parenting.

https://www.jaacap.org/article/S0890-8567(18)30279-X/fulltext