Does Psychotherapy Work?

The Effectiveness of Psychotherapy:
What Has a Century of Research Taught Us About the Effects of Treatment?
– A paper by Dr.
Michael Lambert

The effectiveness of psychotherapy has been subjected to scientific scrutiny since the 1930s.  The activities that characterize psychotherapy practice have evolved over time and today consist of many well established procedures and theories aimed at reducing psychological pain and enhancing the patients’ quality of life.  In this brief summary, some of the most notable findings are reviewed and their implications highlighted.

Psychotherapy is effective. Hundreds of studies have now been conducted on the effects of psychotherapy, including research on psychodynamic, humanistic, behavioral, cognitive, and variations and combinations of these approaches.

Reviews of this research, both qualitative and quantitative, have shown that about 75% of those who enter treatment show some benefit (Lambert & Ogles, in press).

This finding generalizes across a wide range of disorders with the exception of biologically based disturbances, such as bipolar disorder and the schizophrenias, where the impact of psychological treatments is secondary to psychoactive medications.  Within disorders there is

variability, such that some disorders yield to treatment more easily (e.g., phobias, panic) than others (e.g., obsessive compulsive disorder), and some require longer and more intense interventions.

For the most part, psychological interventions surpass the effects of medication for psychological disorders and should be offered prior to medications (except with the most severely disturbed patients), because they are less dangerous and less intrusive, or at the very least, in addition to medications, because they reduce the likelihood of relapse once medications are withdrawn (Thase, 1999: Elkin, 1994).

The effects of psychotherapy are more powerful than informal support systems and placebo controls. Figure 1 (page 13) provides an illustration drawn from numerous studies and reviews of the literature in which researchers designed experiments in which patients were randomly assigned to a no-treatment control, a placebo control group, or a psychotherapy treatment.  These experimental designs allowed researchers to narrow down the causes of improvement while isolating, and ruling out competing factors that might have accounted for improvements that were observed.

As can be seen, patients who do not get psychotherapy improve, probably as a result of seeking support from friends, family, clergy, and the like.  Patients who enter a placebo control fare even better than untreated patients, probably as a result of having contact with a therapist, their expectation of being helped, and the reassurance and support they receive during the study.  In contrast, patients who enter psychotherapy clearly have much better outcomes.

The outcomes of psychotherapy are substantial. Those who have studied psychotherapy have been rigorous in defining and measuring important factors of individual functioning.  Froyd, Lambert, and Froyd (1996), in a survey of outcome practices, reviewed 20 scientific journals published over a five-year period.  They found

that measures of outcome included patient reports, physiological changes, expert judge ratings, ratings by family members, friends and coworkers, as well as employment, medical, and legal standing (e.g., arrest, incarceration).    These rating sources tapped a variety of areas of functioning, mainly psychiatric symptoms (e.g., anxiety, depression,anger, stress), interpersonal functioning (e.g., family conflict, loneliness, intimacy), and social role performance (e.g., conflict at work, absenteeism, employment status).   These factors are of considerable importance to the patient, the family, and society at large.  In addition, much recent effort has been expended to define what a normal state of functioning is and how to assess the degree to which patients have attained this normative state at the end of treatment (Jacobson & Traux, 1991).

The outcomes of therapy tend to be maintained. Numerous follow-up studies have tracked patients after leaving treatment, for periods ranging from six months to over five years.  These studies are fairly consistent in demonstrating that treatment effects are enduring. For example, reviews  of depression (Nicholson & Berman, 1983;  Robinson, Berman, Neimeyer, 1990), social phobia (Feske &Chambless, 1995), substance abuse (Stanton & Shadish, 1997), agoraphobia and panic (Bakker, van Balkon, Spinhover,

Blaauw, & van Dyck, 1998), pain (Flor, Fydrich, & Turk, 1992), generalized anxiety disorder (Gould, Otto, Pollack & Yap, 1997), and many other disorders (Carlson, 1993: Murtagh &Greenwood, 1995; Sherman, 1998; and Taylor, 1996) all demonstrate maintenance of gains for at least one year after treatment.

Psychotherapy is relatively efficient. Research on psychotherapy has examined the speed which patients improve over the course of treatment.  Studies have examined the length of treatment and outcome using numerous research designs.  This has important practical as well as social policy implications.  Howard, Kopta, Krause, and Orlinsky (1986) showed that the more psychotherapy, the greater the probability of improvement, with diminishing returns after about six months.  Thus the power of treatment is most apparent early in the process.  Most recently, Anderson and Lambert (in press) as well as Lambert, Hansen, and Finch (in press), collected data from large samples of patients undergoing treatment who rated their symptoms, interpersonal relations, social role performance, and quality of life on a weekly basis before each treatment session.  Thus, their outcome was assessed from the beginning of treatment until it was completed or they withdrew.

Their progress over time was studied using statistical methods to model the number of sessions needed for a patient to return to a normal state of functioning (i.e., have no more symptoms than people  in the general population).  Figure 2 (page 13) presents the percent of outpatients who have recovered after each additional session of treatment.  As can be seen, about one third of patients will recover by the 10th session, 50% by the 20th session, and 75% by the 55th session. This means that if session limits are set by insurance companies, institutions, and government agencies, half of those coming for treatment will be underserved with a benefit that is less than 20 sessions.  For about 25% of patients, even 50 sessions will not be sufficient to bring them back into the ranks of normal functioning.

Psychotherapy is for better and for worse. Despite the overall positive findings, a portion of patients who enter treatment are worse off when they leave treatment than when they entered.  Lambert and Ogles (in press) estimated that about 5 to 10% of patients deteriorate during treatment, and an additional 15-25% show no measured benefit.  This finding has been reported by other reviewers (Mohr, 1995) and supports the need for regulation by state licensing boards, the legislature, and professional associations.  This rate of deterioration can be reduced if these governing bodies move to maintain high standards of practice by keeping untrained persons from providing services that require professional judgment and the highest level of ethical practice.

As disheartening as it is to know that psychotherapy may be harmful for a small portion of patients and impotent with many others, it also points to the need for quality assurance mechanisms that reduce these occurrences to their lowest possible levels.  Lambert et al. (in press) have shown that if patient progress is tracked on a weekly basis, and decision support tools are used to identify patients who are not responding to treatment in the first three sessions, then providing feedback to therapists about this fact improves outcome and decrease patient deterioration.  Outcome management systems are being developed and these systems are likely to enhance outcomes for the failing patient.

These authors also reported that the use of such systems were cost effective because therapists who received feedback tended to terminate cases who had improved rapidly after fewer sessions (85% of cases), while retaining patients who were identified as failing for more sessions.  This proved to be satisfying to all involved (therapists, administrators, and patients), but the data also indicated  that many of the difficult patients were still in need of further, additional, or different treatment.

Nevertheless, monitoring patient progress and providing feedback to therapists promises to make behavioral healthcare efforts self-correcting and ultimately, more effective.

Psychologists can be proud of the results of their services. Few areas of medicine have received more empirical support for their treatments than those offered by psychologists.

It is clear from the hundreds of studies that have been completed and published that psychotherapy is effective, efficient, and lasting. Psychotherapy has a promising future as the treatment of choice for psychologically-based disorders— reducing suffering, and returning patients to levels of functioning characteristic of their undisturbed peers.

In addition, it has been clearly demonstrated that psychological treatments can offset the costs of medical services by reducing the length of hospital stays and related expenses for patients who have physical disorders (Chiles, Lambert, & Hatch, 1999).

Michael J. Lambert, Ph.D.

Dr. Lambert is professor of psychology at Brigham Young University in Provo, UT.  Dr. Lambert can be reached at  References available upon request.

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