www.lesswrong.com/posts/JnKCaGcgZL4Rsep8m/schools-proliferating-without-evidence
2 corrections found
In the entire absence of the slightest experimental evidence for their effectiveness, psychotherapists became licensed by states, their testimony accepted in court, their teaching schools accredited, and their bills paid by health insurance.
This absolute claim is incorrect: by the late 20th century, psychotherapies such as cognitive therapy and interpersonal psychotherapy had already been tested in many controlled trials and shown efficacy for some conditions.
Full reasoning
The problem is the phrase "entire absence of the slightest experimental evidence". That is much too strong.
There was already substantial experimental evidence for at least some psychotherapies well before this 2009 post. For example:
- A 1998 PubMed-indexed meta-analysis reported that cognitive therapy had been studied in 78 controlled clinical trials from 1977 to 1996 and concluded that "CT is effective in patients with mild or moderate depression."
- A 1997 PubMed review of interpersonal psychotherapy (IPT) states that IPT was "tested in randomized clinical trials" and that "evidence from controlled clinical trials suggests that IPT is a reasonable alternative or adjunct to medication" for major or mild depression and some other conditions.
So even if one thinks many psychotherapy schools were weakly evidenced, it is factually wrong to say there was an entire absence of experimental evidence for psychotherapy effectiveness. There was experimental evidence for at least some therapies, including controlled trials and meta-analyses.
2 sources
- A meta-analysis of the effects of cognitive therapy in depressed patients - PubMed
Background: Cognitive therapy (CT) has been studied in 78 controlled clinical trials from 1977 to 1996... Conclusion: CT is effective in patients with mild or moderate depression.
- Interpersonal psychotherapy: current status - PubMed
Interpersonal psychotherapy (IPT)... was developed, defined in a manual, and tested in randomized clinical trials... evidence from controlled clinical trials suggests that IPT is a reasonable alternative or adjunct to medication as an acute, continuation, and/or maintenance treatment for patients with major or mild depression.
But there is no statistically discernible difference between the many schools of psychotherapy.
This is too absolute. Controlled trials have found statistically significant differences between psychotherapies for some disorders—for example, CBT and prolonged exposure have outperformed supportive therapies in randomized trials.
Full reasoning
The sentence claims that psychotherapy schools show no statistically discernible differences. That blanket statement is not correct.
There are randomized controlled trials showing significant differences between psychotherapies for particular disorders:
- In a 2000 randomized controlled trial for social phobia, researchers compared cognitive behavior therapy (CBT) with supportive therapy and found that CBT was better on the main social-phobia measure at week 6, better on most measures at week 12, and had a significantly higher responder rate.
- In a 2007 JAMA randomized controlled trial for PTSD in women, prolonged exposure (a form of CBT) produced a greater reduction of PTSD symptoms than present-centered therapy (P = .03), and patients receiving prolonged exposure were more likely to no longer meet PTSD diagnostic criteria.
These results do not mean every therapy differs from every other therapy in every context. But they do disprove the categorical claim that there is no statistically discernible difference between psychotherapy schools.
2 sources
- Cognitive behavior therapy versus supportive therapy in social phobia: a randomized controlled trial - PubMed
Results: At week 6, after CT, group 1 was better than group 2 on the main social phobia measure. At week 12... group 1 was better than group 2 on most of the measures and demonstrated a significantly higher rate of responders. Conclusions: CBT was more effective than ST.
- Cognitive behavioral therapy for posttraumatic stress disorder in women: a randomized controlled trial - PubMed
Results: Women who received prolonged exposure experienced greater reduction of PTSD symptoms relative to women who received present-centered therapy (effect size, 0.27; P = .03)... The prolonged exposure group was more likely... to no longer meet PTSD diagnostic criteria.