Contemporary Problem-Solving Therapy, or PST, is a transdiagnostic intervention, generally considered to be under a cognitive-behavioral umbrella, that increases adaptive adjustment to life problems and stress by training individuals in several affective, cognitive, and behavioral tools. The training is aimed at several barriers to effective problem solving. Through experiential practice, PST helps people to train their brains to overcome common barriers to the way they react to and attempt to solve real-life problems. PST usually lasts 12 sessions; however, effective changes have been observed in PST programs with as few as 4 sessions and may extend to long-term intervention when individuals have long-term and inflexible problem-solving styles or a high degree of emotional dysregulation.
Here is a meta-analysis of 31 studies of PST: Malouff, JM, Thorsteinsson, EB, and Schutte, NS. (2007). The efficacy of problem solving therapy in reducing mental and physical health problems: A meta-analysis. Clinical Psychology Review, 27(1), 46-57.