The majority of studies on the effectiveness of psychotherapy have reported results for relatively short follow-up times.

In this study the effectiveness of short- and long-term psychotherapy was compared during a very long follow-up.

A total of 326 psychiatric outpatients with mood or anxiety disorder were randomly assigned to solution-focused therapy (12 sessions), short-term psychodynamic (20 sessions) and long-term psychodynamic psychotherapy (240 sessions) in Helsinki Psychotherapy Study. The patients were followed from start of treatment and assessed 11 times during a 7-year follow-up. Symptom Check List (anxiety, depression, and general symptom scale), Work-subscale of the Social Adjustment Scale, and use of auxiliary treatment (psychotherapy, psychotropic medication, and psychiatric hospitalization) were used as outcome measures.

A reduction in psychiatric symptoms and improvement in work ability and functional capacity was noted in all treatment groups. The short-term therapies were more effective than long-term psychotherapy during the first year, whereas the long-term therapy was more effective after 3 years of follow-up. No significant differences were observed between long- and short-term therapies during the 4 last years of follow-up.A total of 80% of the patients in the short-term therapy groups and 60% in the long-term therapy group used auxiliary treatment.

Short-term psychotherapy gives faster benefits than long-term psychotherapy, but in the long run no notable differences in symptoms or working ability are seen. Considerably auxiliary treatments are taken after the end of the intervention implying further need of treatment. These findings should be repeated in other populations.