The prevalence of common mental disorders (CMDs) such as depression and anxiety disorders is increasing, with depression now the leading cause of disabilities globally,¹ meaning that governments must take decisive actions to finance evidence-based support for these conditions. Psychological therapies, such as cognitive–behavioural therapy (CBT), are recommended as first-line treatments for many CMDs. However, access to these treatments is poor despite the evidence of short- and long-term benefits and cost-effectiveness.^{Reference Cuijpers, Miguel, Harrer, Plessen, Ciharova and Ebert2} Convincing governments and healthcare commissioners to allocate the necessary resources for expanding access to effective psychological treatments is challenging, especially in the current economic climate. The public health benefits of doing so are well founded, but in many countries, this has not yet proven convincing enough to greatly affect healthcare policy or spending. Beyond the public health benefits, it has been suggested that reducing symptoms of CMDs leads to improved productivity at work and fewer absences, and to increased national taxable income.^{Reference Layard, Clark, Knapp and Mayraz3}

The National Health Service (NHS) Talking Therapies for Anxiety and Depression (TTad) programme (formerly known as Improving Access to Psychological Therapies [IAPT]) in England was established with the anticipation of economic returns, a model that has been followed by a small number of countries (in specific regions mainly), including Norway, Canada and Australia. Although the rates of symptomatic improvements in these services are well evidenced,^{Reference Clark4} there are fewer data available to assess the economic effects of these treatments. In Spain, the Psychology in Primary Care (PsicAP) randomised control trial was conducted to evaluate the impact of adding a transdiagnostic-CBT (TD-CBT) intervention (akin to much of the treatment within NHS TTad) to treatment-as-usual (TAU), compared with TAU alone in Spanish primary care services. There was greater symptom-related benefit at post-treatment and at 12-month follow-up for TD-CBT + TAU compared with TAU alone,^{Reference Cano-Vindel, Muñoz-Navarro, Moriana, Ruiz-Rodríguez, Medrano and González-Blanch5} with medium effect sizes observed and similar rates of recovery compared with NHS TTad services (near 50%). PsicAP trial participants also reported their income (categorised as ‘<€12 000’, ‘€12 000–€24 000’, ‘€24 000–€36 000’ and ‘>€36 000’ per annum) pre- and post-treatment, and at 3-, 6- and 12-month follow-up time points. We compared the proportion of individuals reporting an annual income of >€24 000 (approximate to the average annual income in Spain) between the treatment groups at each time point (see Fig. 1). The differences between interventions expressed as odds ratios were: 1.13 (95% CI: 0.84–1.52) at pre-treatment; 1.36 (95% CI: 0.94–1.98) at post-treatment and 1.92 (95% CI: 1.21–3.05) at 12-month follow-up. From Fig. 1 we can see that the proportion of TD-CBT + TAU participants earning over €24 000 increased steadily to the point that nearly double the proportion of these people were above this threshold at 12 months, whereas there was very little change for those receiving TAU alone (i.e. not receiving psychological treatment).

Fig. 1 Percentage of patients with an income above €24 000 in the TD-CBT + TAU compared with TAU alone. TAU, treatment as usual; TD-CBT, transdiagnostic cognitive–behavioural therapy.

These findings suggest the potential for psychological treatment delivered in primary care to increase earning ability, and hence the potential that psychological interventions can increase economic growth through increasing income. If services that could deliver such treatments at scale were developed and further expanded internationally, it is likely that they would not only ‘pay for themselves’, but would also lead to a net cost-benefit in the medium-term.^{Reference Layard and Clark6}

At the end of November 2023 the British government committed to a large increase in funding to NHS TTad as part of its ‘Back to Work Plan’,⁷ acknowledging the role of psychological treatment services in supporting people to return to or maintain their employment, and to increase their earnings. As our data show, investing in access to scalable psychological therapies for common mental health problems may not only reduce healthcare costs but can also be a path to economic growth through improved income. Further demonstrating the economic benefits of widespread access to psychological therapies for CMDs is crucial for advocating the expansion of these services, contributing to reducing inequality in access and alleviating the global burden of CMDs.^{Reference Henking8}