Buck without bang: getting mental health investments to scale

ONE of the most puzzling features of recent Australian mental health investments and reform has been the apparent stability of the prevalence of mental illness. Total expenditure on mental health services in Australia (public and private) more than doubled from $5.8 billion in 2008–09 to $11 billion in 2019–20. Over the same period, the Australian Government expenditure on mental health-related services rose from $120.38 per capita to $149.63. Most of this increase was due to the inclusion of psychology services under Medicare, as part of the Council of Australian Governments National Action Plan on Mental Health, established in 2006. The impact of this increase in spending has been to lift the rate of public access to mental health care from 35% in 2007 to 47% in 2020–21. Eleven per cent of Australians (2.9 million people) accessed 14 million Medicare-subsidised mental health-specific services in 2020–21, an increase from 7% in 2010–11.

Although substantial increases in the provision of care and public access have occurred, they have not necessarily been equitable, with access to mental health care varying depending on where people live and many Australians facing considerable out-of-pocket costs.

The prevalence of mental illness also appears to have changed very little. The Australian Bureau of Statistics (ABS) found that one in five Australians had a 12-month mental disorder in 2007 and again in 2020. Evidence from Australia and overseas suggests this is unsurprising, with little observable relationship between increased provision of care and reduced prevalence.

This has led some to question the effectiveness of increasing access to current treatments as a means of improving population mental health, instead calling for greater emphasis on primary prevention of common mental disorders. Mental health receives just over 7% of the total health budget in Australia but accounts for around 12% of the burden of disease. Arguments to close this gap are hard to sustain when evidence for the impact of spending is wanting.

So how to reconcile this puzzle, where more mental health treatment does not seem to result in lower prevalence?

We developed a system dynamics model of mental disorder incidence and treatment-dependent recovery to assess two potential explanations. The first was that there has been an increase in the individual-level risk of disorder onset – in other words, that while overall prevalence may be unchanged, this stability masks an increased level of high to very high psychological distress. The second explanation was to consider declining effectiveness of care resulting from insufficient services capacity growth.

Bayesian statistical methods were used to fit the system dynamics model to key Australian datasets (ABS; Australian Institute of Health and Welfare; the Household, Income and Labour Dynamics in Australia [HILDA] Survey) for the period 2008–2019. Estimates of yearly rates of increase in the per capita incidence of high to very high psychological distress and the proportion of patients recovering when treated indicate that the individual-level risk of developing high to very high levels of distress increased between 2008 and 2019.

However, we found no evidence for declining treatment effectiveness. Simulation analyses suggest that the prevalence of high to very high psychological distress would have decreased from 14.4% in 2008 to 13.6% in 2019 if per capita incidence had not increased over this period, which equates to a 5.47% reduction in the number of people with high to very high psychological distress in 2019.

The conclusion arising from this dynamic modelling analysis is therefore that an increase in the prevalence of high to very high psychological distress in Australia from 2008 to 2019 is attributable to an increase in the per capita incidence of higher levels of distress, rather than declining treatment effectiveness.

So, although the overall prevalence of mental illness may be stable in the community, our modelling suggests problems may be becoming more severe. Even though the causes of this are unclear, there are several relatively recent economic and social phenomena that could plausibly contribute, including increasing underemployment, declining employment security, increasing household debt, a decline in the frequency of social interaction, and increasing loneliness.

What these results show, contrary to previous contributions to the treatment-prevalence puzzle, is that if the per capita incidence of high to very high psychological distress had remained stable over the study period, increasing treatment-dependent recovery associated with a substantial increase in access to mental health care would have in fact produced a modest but significant decrease in the proportion of people with high to very high K10 (Kessler Psychological Distress Scale) scores.

System dynamics modelling offers an opportunity to better grasp and respond to the complex, fluid nature of mental health, and to advance the contentious debate (prevention versus treatment) by providing a platform for exploring the robustness of our hypotheses. The implications arising from this work are significant.

The work suggests that while there has clearly been increased mental health treatment provision in Australia from 2008 to 2019, the scale of the investment was insufficient to offset a concurrent increase in the incidence of high to very high psychological distress. New funding has failed to deliver the desired, palpable impact on community mental health but for reasons of scale, not target. Although attention to mental health has grown, commitments to reform and funding have been sporadic, with significant national investments made roughly every five years since 2006. Mental health remains characterised by underinvestment.

In fact, an earlier study provides evidence that the current pattern of severe underinvestment in public mental health services in Australia, and particularly in more effective early intervention services, perpetuates a grossly inefficient and more costly mental health care system. It concluded that “if we persist with ‘business as usual,’ nearly three times the number of mental health services currently provided per year will be required to ensure that all Australians seeking mental health care receive timely and effective treatment”. The modelling demonstrated that actual expenditure on mental health services in 2018−19 was $14.4 billion less than the $22.7 billion needed.

The modelling justifies addressing this underinvestment, suggesting there is merit not only in continued spending on mental health services but in expanding it as a legitimate and effective contribution to population mental health strategies. Addressing the substantial and persistent ‘treatment gap’ for mental disorders should remain a global and Australian public health priority, particularly for young people.

This renewed investment should be part of a broader strategy here in Australia, aimed at delivering equitable and affordable mental health care, boosting targeted prevention and earlier intervention activities, dealing with the psychosocial aspects of good mental health, and delivering genuine accountability to drive systemic quality improvement.

Dr Sebastian Rosenberg is Senior Lecturer at the Brain and Mind Centre, University of Sydney

Associate Professor Jo-An Occhipinti is the Head of Systems Modelling, Simulation and Data Science; and Co-Director of the Mental Wealth Initiative at the Brain and Mind Centre, The University of Sydney. She is also the Managing Director of Computer Simulation and Advanced Research Technologies (CSART) Ltd.

Dr Adam Skinner is a mathematical modeller and statistician at the University of Sydney’s Brain and Mind Centre. His research focuses on the development of computer simulation models designed for use as decision support tools by health policy makers.

Professor Hickie is a Professor of Psychiatry and the Co-Director of Health and Policy, Brain and Mind Centre, University of Sydney. He has led major public health and health services developments in Australia, particularly focusing on early intervention for young people with depression, suicidal thoughts and behaviours and complex mood disorders.

The statements or opinions expressed in this article reflect the views of the authors and do not necessarily represent the official policy of the AMA, the MJA or InSight+ unless so stated.

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