Thousands of studies have been conducted in the last half-century into whether therapy is successful. The results of these studies provide an unambiguous answer: yes. Among other things, the well-being of participants was compared before, and after therapy. This was done using various indicators of psychological stress. The findings showed that people who underwent therapy had higher levels of well-being compared to before therapy.
However, researchers also like to know if there is a change in the subjective experiences of the client. For example, are there fewer feelings of depression after therapy? To study this, a wide range of psychological questionnaires, global measurements of psychological stress and measurements of specific psychological difficulties were used. Studies using this approach have shown that, on average, clients rate themselves as less psychologically stressed after therapy compared to before therapy.
However, pre- and post-test scores alone are not sufficient to conclude that psychotherapy is responsible for the observed changes in well-being. It could also be the case that the problems simply disappear over time, which is called spontaneous remission. Therefore, it is important to measure change using a control group. This means that the group of individuals who have undergone therapy (the experimental group) is compared to a comparable group of individuals who have not undergone therapy (the control group). In this way, the efficiency of therapy, the potential to produce the desired effect, can be determined with greater certainty.
Studies using a control group show that therapy does indeed produce positive changes.
To rule out that change after therapy is only due to the “active ingredients” of the therapy, research often uses a placebo condition. Placebo consists of a procedure that is credible to the patient, but lacks the expected effective ingredients. Changes in a group of individuals undergoing therapy are then compared to changes in a group of individuals in the placebo condition. This placebo condition often consists of a form of listening, offering support and being a kind of 'friend' to the client. The placebo condition therefore does not contain any active ingredients of therapy, but is still regarded by clients as a therapeutic treatment.
The finding that psychological therapy produces a positive significant change in itself does not tell the whole story. The effect of therapy should also be measured to conclude on its impact. For this, statisticians use the statistical measure 'effect size'. This describes the strength of the relationship between two variables. A variable is something that can take a numerical value. When something has a large effect, it means that two variables are strongly related to each other (e.g. undergoing therapy and well-being). So, a small or non-existent effect measure means that the variables are weakly or not related to each other.
The most commonly used effect measure is Cohens ' d'. A 'd ' of 0.2 is considered a small effect, of 0.5 as a medium effect and of 0.8 as a large effect. This standardized measure allows researchers to combine results from multiple studies, even when using different measurement instruments.
Researchers then use a statistical procedure that brings together results from similar studies to estimate overall effects. This procedure is called a meta-analysis and is one of the most reliable sources of information.
Progress that can be associated with psychotherapy can also be expressed in clinically significant improvement. This means that someone no longer experiences or experiences to a much lesser extent high psychological stress. This is defined on the basis of diagnostic criteria (as in the DSM). Clinically significant improvement involves a shift from abnormally high psychological stress to normal psychological stress.
Effectiveness is the degree to which an intervention, carried out under usual circumstances, produces the desired effect. Studies with clinical representative conditions are used to determine what the actual change will be after therapy. These conditions are also known as real-world conditions. Self-reports can also measure real-world and real-world effectiveness.
There is a significant minority who show no improvement as a result of psychotherapy. In fact, research suggests that 5 to 10 percent deteriorate from therapy. This applies to 10 to 15 percent of clients with a substance addiction.
The median effective dose, or ED50, is used to predict the amount of therapy required. Half of the client group (50 percent) need ten to twenty therapy sessions to recover. However, this number depends on the type of problems/disorders/symptoms.
The more therapy clients undergo, the greater their progress seems to be. However, there is no direct link between the number of sessions and the degree of improvement. However, the law of decreasing yield does exist. From a certain point, undergoing more sessions decreases the benefit of each session (see Figure 2.3 page 28).
Research shows that, on average, clients do not continue to improve after the therapy is finished (= sleeper effect), but do not deteriorate either.
Follow-up is the study of a client at some point after the end of therapy to verify the effectiveness/efficiency of previous treatment(s).
Relapse is a term borrowed from the medical field, meaning a return to ill health after a period of improvement.
Some studies show a faster initial response to medication compared to therapy. However, by the end of therapy, the effect of therapy is equal to or even better than the effect of medication. Furthermore, research suggests that the effect of therapy is more sustainable. It also appears that clients (with depression, for example) prefer therapy over medication.
Therapy in combination with medication does not often appear to have a greater or better effect than therapy alone. However, no evidence has been found for the statement that pharmacological treatment (medication) decreases the effectiveness of psychological therapy.
Cost efficiency analysis
In many studies, the costs of therapy (through conversation) are weighed against the costs of other forms of intervention. Examples of this are medication or hospital admissions, these interventions are necessary when no therapy is used. Research shows that psychotherapy significantly reduces the use of medical care. Many studies also show that psychotherapy is economically beneficial.
However, for mood disorders, for example, where hospitalization is unlikely, psychotherapy is cost neutral (not economically beneficial). Research results that confirm this do not take into account the direct costs for the social and economic well-being of a country caused by mental stress. Think, for example, of absenteeism and reduced employment for people with mental health problems.
Does therapy help? On what is the answer to that question-based?
Why are mere pre- and post-test scores not enough?
What is the significance of clinically significant improvement?
What is effectiveness and how is it determined?
What is the sleeper effect?
Is therapy in combination with medication more effective than therapy alone? Or does medication actually decrease the effectiveness of therapy?
Is psychotherapy economically beneficial and why or why not?
