Psychotherapy Benefits for Depression Persist for Years, Meta-analysis Shows

Sustained Impact of Psychotherapy on Depression

Depression remains a leading cause of disability worldwide, with psychotherapies serving as a cornerstone of treatment for diverse patient groups, from older adults to those with complex comorbidities [1, 2, 3, 4, 5]. While the short-term efficacy of these interventions is well established, a critical question for clinicians and patients alike has been the durability of these benefits over the long term, especially given challenges with treatment adherence and relapse [6, 7]. A recent, large-scale meta-analysis now provides a detailed timeline of psychotherapy's lasting impact, offering clinicians a clearer picture of the expected trajectory of patient improvement for years after initial treatment.

Study Design and Scope

To clarify the long-term persistence of psychotherapy's effects, researchers conducted a comprehensive meta-analysis of randomized controlled trials in adults with depression. The inclusion criteria required studies to compare a psychotherapy against a control condition (such as care-as-usual or a waitlist) and to report outcomes at six months or later, ensuring a focus on sustained effects. The primary outcome was the standardized mean difference (SMD), a statistical measure of effect size. The analysis also assessed clinical response rates and the corresponding risk ratio (RR), which quantifies the likelihood of response in the treatment group versus the control group. To map how these effects changed over time, the authors used a sophisticated statistical method called a multivariate pooling model with cubic regression splines. This technique allowed them to model a flexible, non-linear curve of treatment benefit, rather than assuming a simple straight-line decline. Furthermore, to ensure accuracy, the model accounted for the fact that measurements taken from the same trial at different times are related, a process handled by what are known as continuous-time autoregressive variance-covariance matrices.

Extensive Data Pool

The conclusions of this meta-analysis are built upon an exceptionally large and robust dataset. The investigators synthesized data from 191 randomized controlled trials, which included 209 separate comparisons between psychotherapy and control conditions. This extensive pool of evidence involved a total of 33,691 participants, with 17,715 individuals in psychotherapy arms and 15,976 in control arms, providing substantial statistical power for the analysis. The depth of the follow-up is particularly noteworthy. The included trials contributed a total of 534 follow-up measurements. Critically for assessing long-term durability, 52 of these measurements (9.7%) were taken more than 12 months after patients were randomized. This wealth of long-term data was essential for charting the trajectory of treatment effects far beyond the acute phase of care.

Trajectory of Treatment Effects

The analysis provides a clear and dynamic picture of psychotherapy's impact over several years. Using a flexible statistical model to map the treatment effect, the researchers found that the benefit is both immediate and durable. The standardized mean difference (SMD), which measures the magnitude of the treatment effect, peaked at 0.55 at 12 weeks post-randomization, indicating a large initial benefit. Following this peak, the effect size gradually decreased over the next nine months, stabilizing at an SMD of 0.39 at the one-year mark. Most importantly for clinical practice, this moderate effect did not disappear. The analysis showed that the benefit remained largely stable for years afterward. The SMD remained statistically significant for up to 8.3 years (431 months) after randomization, providing strong evidence that the positive effects of psychotherapy are remarkably persistent.

Response Rates Over Time

In addition to measuring the overall magnitude of effect, the study also evaluated the clinical likelihood of a patient responding to treatment. This was assessed using the risk ratio (RR), which compares the probability of achieving a response in the psychotherapy group to the control group. The findings show that patients receiving psychotherapy were significantly more likely to respond, with the RR peaking at 1.68 after 3 months. This means that during the acute treatment phase, patients in therapy were nearly 70% more likely to achieve a clinical response than their counterparts in control conditions. While this relative advantage moderated over time, it remained clinically and statistically meaningful for an extended period. The RR slowly decreased to 1.14 at the 5-year follow-up, and the benefit remained statistically significant for up to 4.5 years (236 weeks). This demonstrates that psychotherapy provides a durable advantage in achieving and maintaining a clinical response.

Clinical Implications for Long-Term Care

This meta-analysis offers valuable insights for counseling patients about the expected course of improvement with psychotherapy for depression. The data confirm that psychotherapies produce moderate to large effects within the first 3 months, a critical period for building therapeutic alliance and patient hope. Clinicians can confidently communicate that a significant initial benefit is the typical outcome. The findings also provide a realistic picture of the longer-term trajectory. The initial large effect slowly decreases over the following 9 months, stabilizing at a moderate level. It is crucial to note that this is not a loss of efficacy but a transition to a stable, lasting benefit. The most significant conclusion is that this moderate effect remains stable for several years. This evidence allows physicians to frame psychotherapy not as a short-term fix, but as an investment in long-term well-being, helping to manage patient expectations and encourage persistence with skills and insights gained in therapy.

References

1. Mamukashvili-Delau M, Koburger N, Dietrich S, Rummel-Kluge C. Long-Term Efficacy of Internet-Based Cognitive Behavioral Therapy Self-Help Programs for Adults With Depression: Systematic Review and Meta-Analysis of Randomized Controlled Trials. JMIR Mental Health. 2023. doi:10.2196/46925

2. Zahra Z, Effendy E, Mawarpury M, Marthoenis, Jaya I. Psychotherapies for chronic kidney disease patients with hemodialysis: A systematic review of randomized control trials and quasi-experiments.. Narra J. 2023. doi:10.52225/narra.v3i3.215

3. Carl E, Witcraft SM, Kauffman BY, et al. Psychological and pharmacological treatments for generalized anxiety disorder (GAD): a meta-analysis of randomized controlled trials.. Cognitive behaviour therapy. 2020. doi:10.1080/16506073.2018.1560358

4. Gould RL, Coulson MC, Howard RJ. Cognitive behavioral therapy for depression in older people: a meta-analysis and meta-regression of randomized controlled trials.. Journal of the American Geriatrics Society. 2012. doi:10.1111/j.1532-5415.2012.04166.x

5. Huo L, Yu X, Ma Y, Yang L, Li X. Effects of prenatal psychotherapies and psychosocial interventions on depressive symptoms, anxious symptoms and stress: a systematic review and network meta-analysis.. Frontiers in psychiatry. 2025. doi:10.3389/fpsyt.2025.1624924

6. Voderholzer U, Barton B, Favreau M, et al. Enduring effects of psychotherapy, antidepressants and their combination for depression: a systematic review and meta-analysis. Frontiers in Psychiatry. 2024. doi:10.3389/fpsyt.2024.1415905

7. Clement S, Schauman O, Graham T, et al. What is the impact of mental health-related stigma on help-seeking? A systematic review of quantitative and qualitative studies. Psychological Medicine. 2014. doi:10.1017/s0033291714000129