Empirical evidence on whether patients’ mental health and functioning will be more improved after long-term than short-term therapy is scarce. We addressed this question in a clinical trial with a long follow-up.

In the Helsinki Psychotherapy Study, 326 out-patients with mood or anxiety disorder were randomly assigned to long-term psychodynamic psychotherapy (LPP), short-term psychodynamic psychotherapy (SPP) or solution-focused therapy (SFT) and were followed for 10 years. The outcome measures were psychiatric symptoms, work ability, personality and social functioning, need for treatment, and remission.

At the end of the follow-up, altogether 74% of the patients were free from clinically elevated psychiatric symptoms. Compared with SPP, LPP showed greater reductions in symptoms, greater improvement in work ability and higher remission rates. A similar difference in symptoms and work ability was observed in comparison with SFT after adjustment for violations of treatment standards. No notable differences in effectiveness between SFT and SPP were observed. The prevalence of auxiliary treatment was relatively high, 47% in SFT, 58% in SPP and 33% in LPP, and, accordingly, the remission rates for general symptoms were 55, 45 and 62%, respectively.

After 10 years of follow-up, the benefits of LPP in comparison with the short-term therapies are rather small, though significant in symptoms and work ability, possibly due to more frequent use of auxiliary therapy in the short-term therapy groups. Further studies should focus on the choice of optimal length of therapy and the selection of factors predicting outcome of short- v. long-term therapy.