Psychotherapy frequency more crucial than session count, study suggests

A recent study published in the Journal of Affective Disorders has provided new insights into the most effective ways to deliver psychotherapy for adult depression. Researchers investigated how various indicators of the amount and frequency of psychotherapy sessions are related to treatment outcomes. The key findings suggest that while the number of sessions and total contact time with therapists do not significantly impact effectiveness, the frequency of sessions does.

Depression remains a significant public health challenge, being one of the leading causes of disability worldwide. Despite the proven effectiveness of psychotherapy in treating depression, the optimal amount and frequency of therapy sessions remain unclear.

Efficiently delivering psychotherapy could potentially reduce the disease burden by maximizing the effectiveness of treatment while minimizing costs. In their new study, researchers aimed to clarify how the amount and frequency of psychotherapy sessions impact treatment effectiveness, thereby informing better clinical practices and resource allocation.

“We know that adult depression can be effectively treated by psychotherapy, but we are still not sure what the amount and frequency leading to the highest effectiveness is,” said study author Marketa Ciharova, a PhD student at the Vrije Universiteit Amsterdam. “That is important know so that we deliver enough psychotherapy for it to be effective. However, we also need to know when additional sessions do not improve the effects, because then we can save both the client and the therapist time. The therapist can then accept more clients, which is crucial especially nowadays when waiting lists in mental health care are very long.”

The study utilized data from randomized controlled trials (RCTs) that compared individual, face-to-face psychotherapy with control conditions like care-as-usual or waitlist. Meta-regression analyses, a statistical method that examines the relationship between study characteristics and treatment effects, were employed to analyze the data.

Researchers conducted a comprehensive search of multiple bibliographic databases, including PubMed, PsycINFO, Embase, and the Cochrane Library, to compile relevant studies. The inclusion criteria were strict: studies had to be RCTs conducted on adult participants diagnosed with depression, comparing individual psychotherapy to a control condition. Group therapies, telephone therapies, and self-help interventions were excluded to ensure homogeneity in the analysis.

Data from 176 studies involving 15,158 participants were included. Researchers extracted information on various aspects of the studies, such as the number of sessions, duration of treatment, total contact time, and number of sessions per week. They also assessed the risk of bias in the included studies using the Cochrane Risk of Bias Assessment Tool.

The researchers found no significant relationship between the number of psychotherapy sessions or the total contact time with the therapist and the effectiveness of the treatment. This suggests that simply increasing the number of sessions or the amount of time spent with a therapist does not necessarily lead to better outcomes.

There was a small negative association between the duration of treatment and the effect size, indicating that longer treatment duration was slightly related to lower effectiveness. Specifically, each additional week of treatment was associated with a 0.014 decrease in the effect size.

But a strong positive association was found between the number of sessions per week and treatment effectiveness. Increasing the frequency from one to two sessions per week was associated with a significant improvement in outcomes, with an effect size increase of 0.596. This suggests that delivering sessions more frequently over a shorter period is more beneficial than spreading them out over a longer time.

“It seems that the amount of psychotherapy, no matter whether measured as number of sessions, the duration of therapy in weeks, or minutes spent with the therapist, is not associated with the treatment effects,” Ciharova told PsyPost. “What seems to be important is rather the frequency of session – the more often, the better outcomes.

“However, this association was no longer significant when characteristics of studies were considered. Thus, we suggest that psychotherapy should be planned as short as possible. Only if necessary for content-related reasons, more sessions should be delivered, but as frequently, and over as short period as possible.”

“We did not expect the association between the frequency of sessions and treatment effects to become insignificant when characteristics of studies are considered,” Ciharova explained. “This did not happen in the previous meta-analysis of which the current study was an update (Cuijpers et al., 2013), and it also contradicts findings of a previous randomized controlled trial (Bruijniks et al., 2020).”

However, it is important to note that the analysis is observational and cannot establish causality. “Although the current study certainly provided indications of relationships, the results are only correlational,” Ciharova noted. “The reporting of the included studies was also not optimal, so sometimes, information needed for the analysis was missing. The methodological quality of the included studies also varied.”

Future research should focus on conducting large, high-quality trials to directly compare the effects of different frequencies and amounts of psychotherapy. “The caveats of the current study should be addressed by a large, quality randomized controlled trial,” Ciharova said. “Such trial should also assess how symptoms develop during the treatment, another aspect that we could not address in the current study. Additional investigation is needed in other formats of psychotherapy, as we only assessed individual, face-to-face psychotherapy.”

The study, “Amount and frequency of psychotherapy as predictors of treatment outcome for adult depression: A meta-regression analysis,” was authored by Marketa Ciharova, Eirini Karyotaki, Clara Miguel, Esther Walsh, Nino de Ponti, Arpana Amarnath, Wouter van Ballegooijen, Heleen Riper Bruce Arroll, and Pim Cuijpers.