Is depression overdiagnosed? No

Abstract

Rates of diagnosis of depression have risen steeply in recent years. Gordon Parker believes this is because current criteria are medicalising sadness, but Ian Hickie argues that many people are still missing out on lifesaving treatment

It is appropriate for the wider community to ask if the benefit of the huge increase in the treatment of depression over the past 15 years has outweighed any harm. If increased treatment has led to demonstrable benefits, and is cost effective, then depression is not yet being overdiagnosed. From a health and economic perspective, we can give a clear answer—more adults are alive and well, and we can easily afford to treat more. Increased treatment of depression reduces suicides^{1 2} and increases productivity.³ The provision of appropriate medical and psychological care is also cost effective.⁴

The increased rate of diagnosis has had other benefits, including reduced stigma, removal of structural impediments to employment and health benefits, increased access to life insurance, improved physical health outcomes, reduced secondary alcohol and drug misuse, and wider public understanding of the risks and benefits of coming forward for care.⁵ We have at last abandoned the demeaning labels of stress, nervous breakdown, and adolescent angst. Most doctors can now differentiate normal sadness and distress from more severe and enduring clinical conditions. A new wave of neurobiological, genetic, and psychosocial risk factor studies has also followed,⁶ and brief informational and psychological interventions delivered in person or through the internet now have wide appeal.⁷ In turn, this has stimulated the social psychiatrists to call for a renewed focus on broader societal determinants⁸ and testing of broad preventive strategies in the postnatal, childhood, and adolescent periods.⁵

Health system reform, particularly in the United States and Australia, has emphasised the use of collaborative teams that deliver high quality interventions and achieve desirable health, social, educational, and vocational outcomes.^{9 10} A new generation of health practitioners recognise that clinical forms of anxiety and depression are real and exist commonly outside of mental hospital environments. Without widespread diagnosis of these common conditions, we would all still distance ourselves, our families, and our communities from the benefits of receiving mental health care.

The promotion of safer antidepressant drugs in the early 1990s was clearly the catalyst for change. It challenged the dominant and century old categorical and specialist diagnostic systems. More interestingly, it also reawakened broader community interest in the experiences of people with depression and in how their lives are changed by drug or psychological treatments.¹¹ Population health studies that assess the effect of disability, increase emphasis on prevention and early intervention, and promote the benefits of treatment have resulted from these new perspectives.¹²

Caveats and concerns

Although those under 18 years old seem to benefit from psychological and drug treatments, the evidence is not as strong as for adults.¹³ The resulting community concern should focus on whether drugs or psychological approaches are given as first line treatments rather than whether depression should be diagnosed in young people. As with adults, among young people with more severe disorders the overall response to treatment is encouraging.¹⁴ Although the media often carry stories of young people who have been harmed by treatment, the stories of those who have benefited receive less dramatic coverage.

Closer examination of prescribing patterns¹⁵ reveals other interesting and health promoting patterns. Firstly, although the number of prescriptions for antidepressant drugs rose sharply during the 1990s, it now seems to have slowed. Secondly, the use of new antidepressant drugs often results in reduced prescribing of less desirable sedatives such as benzodiazepines, as well as the more dangerous tricyclic antidepressants and monoamine oxidase inhibitors.¹⁵ Although there has been much hype and regulatory concern about increased prescribing of the new drugs,¹³ there is little hard evidence of harm to a significant number of people. The real harm, as evidenced by the suicide statistics, comes from not receiving a diagnosis or treatment when you have a life threatening condition like depression.

The real action in managing depression is in primary care settings. Large general practice based audits in the United Kingdom, Australia, and New Zealand do not support the notion that depression is now overdiagnosed or treated exclusively with antidepressant drugs. In fact, substantive personal, demographic, geographical, professional, training, and health system capacity barriers remain in place. The net result seems to be that diagnosis of major depression is largely restricted to people with more severe or persistent disorders, those who present many times, those who request treatment, or those who attempt self harm.¹⁶

New clinical model

Although the critics may be reassured by these findings, these low recognition rates should be quite concerning. Most major mental disorders start before the age of 25 years and result in lifetime reductions in productivity and quality of life.¹⁷ Often the best opportunities for changing this course arise early and before secondary medical, health, educational, and social comorbidity develop. Persistent depression also seems to have specific and enduring effects on brain structure and resultant cognitive function.¹⁸

To respond to these convergent epidemiological and neurobiological trends, modern psychiatry desperately needs a new clinical model¹⁹ that combines early intervention and clinical staging perspectives (analogous to those that have been so successful in cancer care). If this happens, increased rates of diagnosis will be balanced by a move to more overtly dimensional models and less reliance on medical therapies—that is, those with less severe forms or in the early phases of illness will receive the least harmful informational and psychological strategies.

Evidence about the lack of care provided when young people present with psychological disorders to primary care^{16 20} supports the public promotion of the benefits of these more dimensional diagnostic models. We will also need to push for greater access to informational and psychological treatments and concurrent monitoring for possible harms.