Conflict is high in families of children with attention-deficit hyperactivity disorder (ADHD), with parents showing "more negative and ineffective parenting (e.g., power assertive, punitive, inconsistent) and less positive or warm parenting, relative to parents of children without ADHD". PMT targets dysfunctional parenting and school-related problems of children with ADHD, such as work completion and peer problems. Pfiffner and Haack (2014) say PMT is well-established as a treatment for school-age children with ADHD, but that questions persist about the best methods for delivering PMT. A meta-analysis of evidence-based ADHD treatment in children further supports this, as researchers found wide variability in how PMT was carried out across previous studies. This analysis also noted that the clinicians involved in these studies often modified the training based on the needs of the family. This variation however, did not create significant differences in effectiveness of PMT across studies. A 2011 Cochrane review found some evidence that PMT improves general child behavior and parental stress in treating ADHD, but has limited effects on ADHD-specific behavior.  The authors concluded that there was a lack of data to evaluate school achievement, and a risk of bias in the studies due to poor methodology; existing evidence was not strong enough to form clear clinical guidelines with regard to PMT for ADHD, or to say whether group or individual PMT was more effective.A 2009 review of long-term outcomes in children with Tourette syndrome (TS) said that, in those children with TS who have other comorbid conditions, PMT is effective in dealing with explosive behaviors and anger management.The US National Institute of Mental Health has designated the "gap between evidence-based treatments and community services" as an area critically in need of more research; PMT for disruptive behaviors in children with autism spectrum disorders is an area of ongoing research.