'Keeping my son out of trouble' - BBC Denise was "at the end of her tether". Her teenage son was in and out of trouble, stealing mopeds, refusing to go to school and hanging out with gangs. Denise says a family-based therapy known as Multisystemic Therapy (MST), gave them a much needed second chance. Multisystemic Therapy revolves around improving parenting, increasing education and training, reducing offending behaviour, and tackling underlying health or mental health problems including substance misuse. Statistics show that one in 10 children aged five to 16 has a mental health disorder. Conduct disorder, which Joshua has, is the most common disorder in boys.