Depression is increasingly being perceived as a global problem and an epidemic. This perspective is widely articulated by the World Health Organization (WHO), and is clearly evident not only in popular media coverage of health issues, depression-related self-help literature and online resources, but also in government-produced public health material. While the term ‘epidemic’ does not tend to be specifically used in clinical literature (or by WHO), there is, nonetheless, a dominant view of dramatically increased depression prevalence within the sphere of psychiatry/psychology.
There is compelling evidence for dramatic rises in prescriptions for antidepressant medication within the last two decades (as is explored in a separate paper; Mental Health Foundation, 2012). However, the assumption that increased diagnosis reflects a rising rate of depression per se deserves scrutiny. Some psychiatric literature has argued that apparent increases in depression rates are an ‘artefact’ of other factors, including expanding diagnostic criteria and an associated trend towards medicalising distress. This has led to a significant tension within psychiatry and related domains over the scale of ‘the depression problem’.
Given this lack of consensus among mental health professionals and researchers, it is important for us to ask how robust the evidence for the epidemic view is and whether more people really are more likely to be depressed now than in previous eras. Only then will we know whether we are responding appropriately to the problem of depression, both in the clinical sphere and more broadly in society.
This paper explores the evidence for the apparent rise in depression rates by surveying psychiatric and psychological literature on depression. It then considerssome key assumptions that currently underlie the way depression has come to be talked about and responded to in the clinical/academic domain and, ultimately, within popular discourse, and examines other factors that have been identified by critics as fuelling the perception that depression has reached epidemic proportions. The discussion identifies a number of ongoing ‘in-house’ professional debates about the nature, cause and appropriate treatment of depression, highlighting what Summerfield (2006a, p. 161) described as ‘a number of under-examined fault lines running through the medical literature on depression’.
There is a growing perception of a global ‘epidemic’ of depression within academic literature and public health material, which frequently citeWHO’s (2001) projection that depression will have become the second most disabling disease globally by 2020. This perception is compounded by the widely held belief that depression is chronically under-diagnosed in the general population, and therefore generally undertreated. This view is evident in the bulk of contemporary psychiatric and public health literature, which often references WHO estimates that only 25% or less of those suffering depression worldwide have access to treatment. As Summerfield (2006a) observed, depression is consequently widely reported as a ‘largely hidden’ contributor to the global burden of disease. This view of the scale of unrecognised depression morbidity is also clearly evident within New Zealand public health material, such as the Ministry of Health’s website on depression (www.depression.org.nz/). The annual prevalence of major depression in New Zealand is currently recorded as 5.7% (Oakley Browne, Wells, & Scotts, 2006).
Proponents of this ‘epidemic’ view of depression (e.g. Hickie, 2007) argue that all efforts should be made to address this level of unmet need (and associated societal and economic burdens) by targeting this under-diagnosed cohort for diagnosis and treatment. It is considered that improved overall diagnosis rates would likely result in a reduced suicide rate, increased productivity, decreased social stigma and discrimination around mental illness, and improved physical health, as well as a reduction in problems that are often associated with depression, such as drug and alcohol abuse. It is argued that more harm is caused by failing to diagnose serious depression (which may lead to suicide) than by ‘over-diagnosis’ and its consequences, such as the use of antidepressant drugs by those who may not need them; indeed, Hickie (2007) argued that there is little evidence to demonstrate that this is a comparable harm. There is however inconclusive evidence about the extent to which depression is a causal factor of suicide Nock et.al(2009).
It is important to note, however, that for at least two decades, the epidemic view of depression has been the subject of debate within the clinical domain, chiefly by academics/clinicians who propose alternative explanations for the apparent world-wide rise in depression. The following section explores each of the counter-arguments to the epidemic hypothesis, which question the extent to which depression can and should be appropriately classified as a distinct ‘disease’.
The DSM manual, published by the American Psychological Association (APA), classifies specific mental disorders according to patterns of symptoms. It is used by clinicians for diagnosing mental disorders, and also by researchers, pharmaceutical companies, policy makers, and health insurers. DSM is the most widely used diagnostic manual in the United States and many other countries (another widely recognised diagnostic guide, the International Classification of Diseases, criteria for mental and behavioural disorders (ICD-10) is produced by WHO).
The diagnostic category ‘major depression’ was first introduced by DSM in 1980 (DSM III) and has only come into frequent use since this time (McPherson & Armstrong, 2006). As Horwitz (2010) noted, prior to the 1970s mental health treatment and research was underpinned by a considerably broader concept of mental health problems, which saw mental distress as substantially grounded in stress and anxiety. This perspective allowed depression to be considered as a reaction, rather than exclusively as an endogenous disorder.
The 1980 revision of DSM saw a shift from the recognition of generalised conditions to the classification of specificdisease categories, based on the assumption that conditions such as depression ought to be recognised as distinct, clearly identifiable syndromes, with a basis ‘in the brain’ (Mulder, 2008). This attempt to impose diagnostic uniformity and to produce a standardised diagnostic language has often been attributed to psychiatry’s attempts in previous decades to ‘professionalise’ itself through closer alignment with the discipline of science (Greenberg, 2010). As Horwitz (2010) noted, this resulted in a radical shift away from the psychoanalytic model of psychiatry, which had previously been the dominant therapeutic approach.
Previous editions of DSM had reflected a view of mental health as a continuum of behaviour, without clear distinctions between ‘normal’ and ‘abnormal’. However, the 1980 revisions foregrounded a medical model of mental illness, a shift which many have subsequently held responsible for an overly-medicalised response to depression, including the ascendance of pharmaceutical therapies over previously popular psychotherapeutic approaches within psychiatry.
Those who question current diagnostic protocols argue that attempts to definitively categorise depression are based on a fallacious assumption that depression is a ‘distinct and recognizable syndrome’ (Mulder, 2008, p. 239). For example, as Parker (2005, p. 469) noted:
While major depression is commonly viewed as a ‘valid’ psychiatric diagnosis, it fails to meet any of the orthodox criteria for validity. It does not have a clear-cut clinical picture (a depressed mood state being the only obligatory component), its boundaries are unclear (because they reflect dimensional rather than natural cleavages), its natural and treatment history are difficult to predict at an individual level, while cause and response to treatment are again more related to factors in the individual sufferer than being integral to the disorder
Mulder (2008) argued that reliance on descriptive, symptom-based diagnostic criteria is problematic as it does not take into account the significance of contextin contributing to individual mental distress (for example, the presence of environmental stressors), and the relevance of this knowledge for determining an appropriate response. As he noted, the symptoms of depression listed in DSM are in fact commonly experienced in the community, not only by those who are diagnosably ill, but also by those who are experiencing levels of distress commensurate with their circumstances. Thus, as he suggests, ‘the evidence does not support a distinct homogenous illness called DSM depression’ (Mulder, 2008, p. 241), and therefore the usefulness of a standardised treatment response is questionable, as inappropriate diagnosis may be given (or appropriate diagnoses missed).
Critics of DSM also argue that current diagnostic categories set the threshold of diagnosis too low. The reliance on a symptom-counting approach to diagnosis (what Mulder (2008, p. 244) referred to as a ‘checklist mentality’) is seen as creating arbitrary distinctions between categories of disorder, failing to take into considerationdegreesof distress and impairment. Thus, according to this view, apparent increases in specific disorders such as major depression may in fact simply be an artefact of the expansion of diagnostic criteria (Mulder, 2008).
Mulder (2008) argued that to avoid the inappropriate classification of normal distress as mental illness, DSM needs to be refined, with useful changes including a move from the use of simple yes/no questions towards a more in-depth, unstructured interview format. As he noted, ‘The ultimate goal is to more clearly separate the depressed patient from the distressed one’ (Mulder, 2008, p. 245), and this may be better achieved through placing greater emphasis on subjectivesymptoms (i.e. an individual’s own qualitative assessment of their own mood and degree of distress).
There is a need to scrutinise the evidence base for the widespread view of depression as a contemporary worldwide ‘epidemic’. As Mulder (2008) suggested, the orthodox response to depression is underpinned by three assumptions: that there is a clearly definable illness called ‘major depression’, that this illness is increasing and that a medical solution is the most appropriate response. These assumptions need to be revisited and the approaches currently taken to address depression at the level of individual treatment and care, as a public health concern, and at the broader social policy level need to be assessed.
Greenberg (2010, p. 125) argued that depression is an illness whose understanding and treatment still rests firmly ‘in the hands of the medical elite’, even though it is a disease that continues to lack a known biomedical cause. Thus, while the public may assume that there is medical consensus about the ‘facts’ of depression, this is not the case. There is much ongoing debate within psychiatry and related domains about how depression should be defined.
The existence of professional ‘fault lines’ beneath the orthodox view of depression therefore deserves recognition, as it raises the possibility that current diagnostic and treatment protocols may not necessarily provide the best guidance for responding to the problem of depression. As many critics of the ‘epidemic’ view argue, it is time to revisit the diagnosis and measurement of depression, and debate the dominance of a medical model solution for depression. This would require not only serious intellectual and financial investment in therapeutic alternatives to antidepressants (to produce a more balanced evidence base), but also a political and professional will to address issues of context and social structure, and their significance for public mental health policy. As Mulder (2008) argued, whether or not depression is conceptualised as an epidemic, more attention needs to be given to the reasonsfor high rates of depression in the population, rather than exclusively resourcing ‘containment’ strategies such as clinical research, treatment and anti-stigma campaigns.
Citations
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