The principal finding of this study is that problem-solving therapy was more effective than supportive therapy in reducing depressive symptoms and produced greater response and remission rates in older patients with major depression and executive dysfunction. This population is usually more disabled than older depressed patients without executive dysfunction and has greater disability because of the cognitive deficits. By the end of the 12-week trial, more than half of the patients who received problem-solving therapy met criteria for treatment response, and more than 45% met criteria for remission. Problem-solving therapy led to one more remission than supportive therapy for every 5–6 patients receiving these treatments. This is a robust difference, considering that in clinical trials comparing active antidepressant treatments, response rates are closer to 35% and the number needed to treat one person to remission is 10 (31
). The efficacy demonstrated by problem-solving therapy is particularly important because depressed elderly patients with executive dysfunction have poor or slow response to pharmacotherapy (3
This is the first study to demonstrate the efficacy of problem-solving therapy in older patients with major depression and executive dysfunction. Our findings are consistent with previous research demonstrating that problem-solving therapy is effective for depressed, cognitively unimpaired older patients (11
), older medical patients (12
), older adults with macular degeneration (13
), and older adults receiving home health care (32
). In addition to efficacy in geriatric depression, problem-solving therapy has been shown to reduce psychopathology and distress in nondepressed patients with disorders accompanied by executive dysfunction, such as schizophrenia (14
). While problem-solving therapy was more efficacious than supportive therapy, supportive therapy led to substantial reductions in the severity of depressive symptoms and to acceptable response and remission rates by the end of the 12-week trial. In fact, supportive therapy was as efficacious as problem-solving therapy during the first 6 weeks of the trial. Supportive therapy has previously been shown to lead to clinically meaningful symptomatic improvement even when the comparator was found more efficacious (34
). As a consequence, supportive therapy has been recommended as an active intervention for some depressive disorders, including postpartum depression (36
), and depression in day hospital patients (37
). Therapeutic factors common to supportive therapy and problem-solving therapy may explain their comparable performance early in treatment. In both treatments, therapists are empathic, provide a safe environment for patients to discuss their concerns, and offer hope. These nonspecific therapeutic strategies are also important in facilitating continued engagement in psychotherapy and have a beneficial effect on mood over time (38
), and they may explain why differences between the two treatments did not occur until later in the intervention.
The therapeutic advantage of problem-solving therapy over supportive therapy became apparent at weeks 9 and 12 of treatment. Most patients require approximately six sessions to learn the principles of problem solving. In subsequent sessions, patients consolidate use of the entire problem-solving therapy model by solving problems on their own in addition to those worked on with the therapist. The therapeutic effects of problem-solving therapy over supportive therapy occurred after the 6th week, at a time when participants were expected to have acquired adequate problem-solving skills. Therefore, a potential explanation for the late onset of therapeutic advantage of problem-solving therapy is development of new problem-solving skills through the problem-solving model. Our study’s design does not allow us to determine whether problem-solving therapy owes its efficacy to improved problem-solving skills or to other components of the treatment, such as increased hopefulness, self-efficacy, problem resolution, and behavioral activation (10
). Developing measures of these variables suitable for cognitively compromised older populations and identifying mediators of the efficacy of problem-solving therapy would be useful next steps. Beyond its theoretical value, such a study would identify the most salient features of problem-solving therapy, allowing further refinement of its use in community settings.
This study’s main findings should be viewed in the context of its limitations. First, our therapists provided both treatments, a design that might have permitted therapist bias to influence the efficacy of interventions. As in other psychotherapy studies using our design, we attempted to mitigate bias by selecting therapists who did not have previous experience with either intervention, training them to high standards, and continuously monitoring their delivery of both treatments. Assigning each therapist to only one treatment arm would have resulted in a nested design requiring a very large sample size in order to control for therapist-specific effects (39
). Furthermore, a nested design does not guarantee elimination of bias; therapists providing supportive therapy may have realized that they were the control condition had their participants not responded as well as anticipated.
Approximately 21% of older adults who met the study’s selection criteria failed to enter the study because of limited interest or poor adherence to study procedures. However, 91% of those who started treatment remained in treatment until the end of the trial. Thus, our findings may be generalized mainly to patients who have sufficient interest and ability to be engaged in therapy. Furthermore, our sample was highly educated, thus limiting the generalizability of our findings to those with a college education. Although we assessed age at first depressive episode and whether the current episode was a recurrence, we have no information on the duration of the current episode, which may influence treatment outcome.
Study participants had mild executive dysfunction of unknown etiology. It remains unclear whether problem-solving therapy can be administered successfully to patients with more severe executive dysfunction or whether it is effective in patients for whom executive dysfunction evolves into dementia. We did not include a control arm of participants without executive dysfunction, and hence we are unable to determine whether patients with major depression and mild executive dysfunction do as well in problem-solving therapy and supportive therapy as those without executive dysfunction.
This study does not offer information on the stability of problem-solving therapy and supportive therapy effects after the end of the 12-week trial. Our encouraging results need to be followed by investigations of the stability of antidepressant response related to problem-solving therapy, need of maintenance problem-solving therapy, and appropriate maintenance dose of problem-solving therapy. Such studies are particularly warranted in elderly patients with depression and executive dysfunction, a population with a high propensity for relapse and recurrence (3
). Finally, none of the participants were taking antidepressants; only a direct comparison of problem-solving therapy and antidepressant treatment can determine which intervention is better.
Of particular importance in understanding the role of a treatment is determining whether any patient characteristics influence how well patients respond to this treatment. Only a sparse literature exists on predictors and moderators of psychotherapy outcomes in depressed older adults. Comorbid personality disorder, generalized anxiety disorder, and early onset of first depressive episode have been found to compromise response to other psychotherapies (40
). Our results suggest interesting avenues for future exploration regarding problem-solving therapy’s effects for other older adult populations. Problem-solving therapy appeared to have a slight advantage over supportive therapy for older adults with recurrent depression and older adults with functional impairments. In fact, participants with these clinical characteristics who received supportive therapy experienced a slight worsening of depressive symptoms over time. These data suggest that there may be opportunities for the development of treatment selection algorithms based on the clinical characteristics of patients seeking psychotherapy. As the effects were small, and given the complexity of moderation analyses, these results should be reviewed with caution. Future research regarding effects of patient characteristics on relative response to different psychotherapies could inform efforts toward individualized treatment.