Short therapy helped more in year one; long therapy pulled ahead on two measures years later
The Helsinki study randomised 326 outpatients to short or long term therapy and followed them five years. Short therapies did more in year one. Later, long therapy did better on sense of coherence and perceived competence.
Reasonable evidence with real limitations. how we score evidence
Caveat on this rating: One trial, 326 people, Finland; outcomes are self-report questionnaires on functioning and quality of life rather than diagnosis or remission, and the long-term arm received many more sessions, so the comparison is not cost-matched. The result genuinely points both ways depending on the horizon and the measure, and this row keeps both.
Almost every study of therapy length is observational. This one randomised people and followed them for five years, which makes it the fairest test on the record, and its answer is split.
Significant findings
In the Helsinki Psychotherapy Study, Knekt and colleagues randomised 326 outpatients with a mood or anxiety disorder to one of three treatments: solution focused therapy, short term psychodynamic psychotherapy, or long term psychodynamic psychotherapy. Everyone was followed for five years from the start of treatment, with four questionnaires on psychosocial functioning (social adjustment, sense of coherence, perceived competence, dispositional optimism) and one on quality of life.
Year one went to the short therapies. "Short-term therapies improved psychosocial functioning and quality of life more than LPP during the first year." The exceptions were optimism and perceived competence, where short and long psychodynamic therapy did not differ.
The later years partly reversed it. "Later in the follow-up, SOC and perceived competence showed significantly more improvement in LPP than in the short-term therapy groups." The two short therapies did not differ from each other.
The authors' summary holds both halves: "Short-term therapy has consistently more short-term effects on psychosocial functioning and quality of life than LPP, whereas LPP has some additional long-term benefits on psychosocial functioning."
The other direction
If the question is what helps most in the first year, this trial answers: the shorter treatment. If the question is whether long therapy ever adds anything, this trial answers: on two of five measures, years later, yes. A page that quotes only one of those is not reporting the trial.
What this does not show
These are questionnaire measures of functioning and quality of life, not symptom remission, and one trial in one country. The long term group also had far more sessions over the period, so cost is part of any comparison.
Worth asking
Which of these outcomes is the one I actually care about?
Source
Randomized trial on the effectiveness of long- and short-term psychotherapy on psychosocial functioning and quality of life during a 5-year follow-up — Knekt P, Heinonen E, Härkäpää K, Järvikoski A, Virtala E, Rissanen J, Lindfors O (2015)
Indexed peer-reviewed journal
Read the source: https://doi.org/10.1016/j.psychres.2015.05.113
DOI: 10.1016/j.psychres.2015.05.113
How this was scored
- Study design
- Randomised controlled trial
- Funding
- Funding not disclosed
- Published in
- Indexed peer-reviewed journal
- Sample size
- 326
- Preregistered
- not recorded
- Conflicts disclosed
- not recorded
- Independent of proponent
- not recorded
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published September 24, 2026.
Questions
How strong is the evidence behind this?
veisund rates this source "moderate evidence". Reasonable evidence with real limitations. It scores 57 out of 100 on our published rubric. One caveat travels with that badge: One trial, 326 people, Finland; outcomes are self-report questionnaires on functioning and quality of life rather than diagnosis or remission, and the long-term arm received many more sessions, so the comparison is not cost-matched. The result genuinely points both ways depending on the horizon and the measure, and this row keeps both. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
Randomized trial on the effectiveness of long- and short-term psychotherapy on psychosocial functioning and quality of life during a 5-year follow-up — Knekt P, Heinonen E, Härkäpää K, Järvikoski A, Virtala E, Rissanen J, Lindfors O (2015). Published in: Indexed peer-reviewed journal. DOI: 10.1016/j.psychres.2015.05.113. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Randomised controlled trial. Funding: Funding not disclosed. Independence from the proponent is not recorded. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.