There’s misperception among some people today that psychotherapy isn’t effective for serious mental illness and therefore can’t be used to treat it. A person might say, “Well, I have severe depression and have tried therapy on multiple occasions, with little effect.”
Lived experience is an important thing to take into consideration when choosing a treatment option. However, I believe it’s equally important to examine the research too, to see what science has to say to such questions. Can psychotherapy be used to treat serious mental illness, including clinical depression or obsessive-compulsive disorder (OCD)?
Let’s find out.
Through research studies, this article examines the effectiveness of psychotherapy for clinical depression and OCD. While acknowledging that everyone’s experience with treatment is different, only scientific research can answer questions about what treatment holds the best hope for most people with a given condition. It cannot tell us, however, whether a specific treatment will work for you, individually (no medical or psychological research can do that).
Psychotherapy Is Effective for Severe Depression
Let’s start by looking at psychotherapy’s effectiveness in the treatment of clinical depression. Psychologists have long recognized that a wide variety of psychotherapies can be as effective — and in some cases, more effective — than antidepressant medications.
The latest meta-analysis on this topic was done just last year (Cuijpers, 2017). This analysis begins by noting that “since the 1970s about 500 randomized controlled trials have examined the effects of psychological treatments on depression.” That’s no small number. I’d dare say that it is one of the most well-studied topics in clinical psychology.
Cuijpers and his colleagues at the University of Amsterdam have been studying this topic for more than a decade now, compiling and updating a database of every research trial on the topic of psychotherapy’s impact on a person who suffers from depression. They’ve found the following types of psychotherapy have at least 10 control-group, randomized trials:
- Cognitive behavior therapy (CBT) (94 studies)
- Behavioral activation therapy (31 studies)
- Interpersonal psychotherapy (IPT) (31 studies)
- Problem-solving therapy (13 studies)
- Nondirective supportive therapy (18 studies)
- Short-term psychodynamic psychotherapy (10 studies)
CBT has been, by far, the most studied type of psychotherapy in the research literature. Keep in mind that the researchers didn’t include and aren’t talking about case studies, smaller studies without a control group, or other kinds of experimental research. Each of these types of psychotherapy have hundreds of these additional types of less-robust research.
So how effective are these therapies? The researchers report that the number of patients that are needed to be treated in order for one more patient to get better is 3 for all therapies (except for problem-solving therapy, where it is 2). The “number needed to treat” (NNT) is a research measurement meant to be able to translate research-based statistics into real-world numbers. Generally, the lower the NNT researchers report, the more effective a treatment. An ideal NNT is 1. Most medical treatments range in the mid-to-high single digits. An NNT of 3, therefore, is fantastic.
Psychotherapy vs. Medication for Depression
What about when you compare psychotherapy to treatment with an antidepressant medication? The researchers answer, “Our meta-analyses of trials directly comparing psychotherapies and pharmacotherapy for depression indicate that there are no major differences between these two types of treatment.” In short, both types of treatment are effective in treating clinical depression.
What about long-term outcomes? “Although psychotherapy and pharmacotherapy are probably about equally effective in the short-term,” note the researchers, “it is clear that the combination of the two is more effective than either of them alone. In meta-analyses of trials examining these comparisons we found that combined treatment is significantly more effective than pharmacotherapy alone.” In other words, if you’re just taking an antidepressant medication alone to treat your depression, you’re likely not doing yourself any benefit in the long-term.
What About Severe Depression?
Sometimes critics of psychotherapy will make the claim that most of the research done on therapy and depression is only with the “worried well” or mild depression. Such criticism ignores the actual data, however, as this meta-analysis demonstrates. “We found no indication that baseline severity was associated with outcome” (Cuijpers, 2017).
We have shown that, contrary to what is thought by many clinicians, baseline severity is not a significant predictor of outcome and CBT is as effective in severe depression as pharmacotherapy (Weitz et al., 2015). […]
We also found that there is no difference in effects between CBT and pharmacotherapy in patients with melancholic depression or with atypical depression (Cuijpers et al., in press).
And other research confirms that psychotherapy works not just for severe depression — it also seems to work for moderate depression too (Aherne et al., 2017).
Psychotherapy Is Effective for OCD
People with obsessive-compulsive disorder (OCD) wait on average 10 years before seeking treatment (Pozza & Dettore, 2017). The disorder is characterized by intrusive thoughts or impulses and repetitive behaviors, and can affect up to 2 percent of Americans over the course of a lifetime. According to these researchers:
Consistent research through randomized controlled trials showed that individual cognitive behavioral therapy (CBT) including exposure and response prevention (ERP) and/or cognitive restructuring (CR), was the first-line psychological treatment leading to symptom improvement in approximately 70% of treated patients.
ERP is the most studied and effective treatment for OCD. According to (McKay et al., 2015), ERP involves:
developing a hierarchy of presenting symptoms, from least fear producing to most, and then guiding the client through exposure to items on the hierarchy until the highest level items are readily tolerated. In parallel, response prevention is included, whereby the client is asked to refrain from completing the compulsions that would otherwise eliminate the anxiety or distressing emotional reaction, or by reapplying the exposure to the fear stimulus immediately following the completion of compulsions.
These researchers’ findings suggest that: “Over the past several decades, considerable research work has accumulated to show that ERP is an efficacious intervention for OCD.”
Olatunji et al. (2013) did a similar meta-analysis a couple of years earlier, clumping together all types of CBT treatments (which they considered ERP to be a type of) and came away with similar conclusions:
Consistent with predictions, CBT out-performed control conditions on primary OCD symptom outcome measures at post-treatment showing a large effect size. This finding is consistent with prior meta-analyses demonstrating that CBT is highly effective in reducing OCD symptoms (Abramowitz, 1997; Rosa-Alcázar et al., 2008). Importantly, the present study included a number of studies that have been published since these previous meta-analyses, and thus adds to the evidence base of CBT for OCD. The present investigation also found that CBT outperformed control conditions on primary OCD symptom outcome measures at follow-up showing a medium effect size.
In short, CBT therapies — including ERP — are effective in the treatment of obsessive-compulsive disorder, a serious mental illness.
The Takeaway: Therapy Can and Does Treat Serious Mental Illness
The takeaway from this small sample of research is to bust the myth that psychotherapy only treats “mild” mental illness. Or that it can’t be used until a person is “stabilized” on medications. The research data just don’t provide evidence to support these beliefs.
None of this is to say that psychotherapy works for all people, all the time, with every therapist. In fact, psychotherapy remains a frustrating treatment option for many, such as those who’ve tried a half-dozen different therapists over the years and achieved little symptom relief. We don’t yet have a great algorithm for predicting success in therapy, nor why some people seem to benefit from it more than others.
In time, however, I believe such algorithms will become available to help people find the therapist who can most effectively be able to work with them on their condition. Until that time, please understand that while not a perfect process, psychotherapy works. Because the data don’t lie.
Aherne, D.; Fitzgerald, A.; Aherne, C.; Fitzgerald, N.; Slattery, M.; Whelan, N. (2017). Evidence for the treatment of moderate depression: A systematic review. Irish Journal of Psychological Medicine, 34(3), 197-204.
Cuijpers, P. (2017). Four decades of outcome research on psychotherapies for adult depression: An overview of a series of meta-analyses. Canadian Psychology/Psychologie canadienne, 58(1), 7-19.
Foa, E.B., M.R. Liebowitz, M.J. Kozak, S. Davies, R. Campeas, M.E. Franklin, H.B. Simpson. (2005). Randomized, placebo-controlled trial of exposure and ritual prevention, clomipramine, and their combination in the treatment of obsessive-compulsive disorder. Am. J. Psychiatry, 162, 151-161.
McKay, D. Sookman, F. Neziroglu, S. Wilhelm, D.J. Stein, M. Kyrios, D. Veale. (2015). Efficacy of cognitive-behavioral therapy for obsessive–compulsive disorder. Psychiatry Res., 225, 236-246.
Olatunji, B.O., M.L. Williams, M.B. Powers, J.A.J. Smits. (2013). Cognitive behavioural therapy for obsessive-compulsive disorder: a meta-analysis of treatment outcome and moderators. J. Clin. Psychiatry, 47, 33-41.
Pozza, A. & Dèttore, D. (2017). Drop-out and efficacy of group versus individual cognitive behavioural therapy: What works best for obsessive-compulsive disorder? A systematic review and meta-analysis of direct comparisons. Psychiatry Research, 258, 24-36.
Weitz, E. S., Hollon, S. D., Twisk, J., van Straten, A., Huibers, M. J., David, D., Cuijpers, P. (2015). Baseline depression severity as moderator of depression outcomes between cognitive behavioral therapy vs pharmacotherapy: An individual patient data meta-analysis. Journal of the American Medical Association Psychiatry, 72, 1102–1109. http://dx.doi.org/10.1001/jamapsychiatry.2015.1516