Date Published: April 4, 2017
Publisher: Public Library of Science
Author(s): Vikram Patel
Abstract: In an Essay to highlight World Health Day 2017, Vikram Patel proposes a staged model, from wellness to distress to disorder, for classifying depressive symptoms.
Partial Text: The past two decades have witnessed the production of a large evidence base from diverse disciplinary perspectives on the human experience that psychiatry classifies as depression. The fundamental problem with this diagnosis is that, in mimicking the model used for classifying other health conditions, a binary classification has been imposed on the continuum of mood to distinguish “cases” from “noncases.” This binary model is unsuitable for depression because there is no clear defining line which discriminates between the miseries of daily life from the “disorder” that can benefit from a clinical intervention. While the hunt for a biomarker to enable the accurate discrimination of those individuals who may require clinical interventions continues apace, there are no promising leads on the horizon. Further, given there is no obvious point in the distribution of symptoms of depression that demarcates the “well” from the “ill,” it is highly unlikely that we will ever find such a biomarker that can neatly distinguish those who are “depressed” from the rest of the population. Thus, the current approach, constrained by binary models of defining when a person may have a disorder, must be content with relying entirely on eliciting symptoms related to the inner emotional worlds of a person (the hallmark ones being feeling miserable, losing interest in things, and feeling profoundly fatigued), assessing the duration and impact of these symptoms, and, based on an arbitrary algorithm, using this information to arrive at a “diagnosis.” Critiques of the binary approach have pointed out that it risks medicalizing normative human responses to adversity and loss (a “category fallacy”) and that applying a binary categorization to a phenomenon that is so obviously continuously distributed in the population is fundamentally unsound . A dimensional approach, consistent with that proposed by the National Institute for Mental Health’s Research Domain Operating Criteria , is proposed as a more valid alternative. However, while dimensions are useful for social and neuroscientists, categories have the greatest utility for health workers and policy makers. Thinking dimensionally helps one understand problems, whereas acting categorically helps one solve them. Both matter to people who are experiencing depressive symptoms. One potential way forwards to find a balance between these two poles is by modifying the binary model into an ordinal one, a hybrid equivalent of the Likert scale, from wellness through distress and disorder of increasing severity or chronicity (Table 1).
A hybrid model is consistent with the “staging” of psychiatric disorders, advocated for more than a decade , in response to the concerns that binary diagnoses mask the heterogeneity of presentations and trajectories within each diagnostic category, and the consequent “one size fits all” approach leads to under- or overtreatment of a significant proportion of individuals with the diagnosis. Indeed, one of the key merits of staging is its direct relevance to the selection of appropriate interventions (Table 1). In the recent trial of the Healthy Activity Program (HAP), a brief psychological treatment based on behavioural activation for severe depression in primary care in India, up to 90% of individuals with depressive symptoms meeting binary criteria for a diagnosis had mild to moderate severity . The staging approach would recategorize these individuals as having a distress syndrome (typically, a mixture of mood, anxiety, and somatic symptoms). The majority of these individuals would do just as well with low-intensity interventions such as self-care, web-based psychological therapy, and social support as with clinical interventions ; indeed, baseline severity is the most consistent moderator of the effectiveness of clinical interventions, which are mostly effective for the severe forms of depression [10,11].
A key barrier to implementing this staged model and integration of the management of a depressive episode in routine health care is the very low rates of detection of these disorders. The traditional approach to improve detection has been through training of primary care workers, despite decades of frontline experience showing that this approach has little sustainable effect. Recent randomized controlled trials in low- and middle-income countries further confirm the limited value of training alone [18,19]. While the low detection rates are likely to be the result of multiple factors, including the lack of skills or resources to respond to a diagnosis and the fear of being overwhelmed by more work, we must recognize that training alone is an inadequate intervention for improving detection. An alternative may be to incorporate screening of adults in primary care and maternal health care platforms using locally validated symptom measures such as the Patient Health Questionnaire-9 (PHQ-9), as has been recommended by the US Task Force on prevention . These measures are brief, acceptable to patients, and their scalability can be enhanced by delivery in graded steps (e.g., asking two “core” questions of the PHQ-9 to all patients and the remainder only to those who respond positively to at least one) or digitally (e.g., through apps while the patient is waiting to see the health worker). Moreover, these tools can also be used to track clinical progress (including remotely through smartphone apps) and for remote supervision of frontline workers, as has been done with high levels of acceptability in the United Kingdom’s Improving Access to Psychological Treatments program . However, screening must always be seen as only the first step of a comprehensive depression care program, for screening alone without any strategies to ensure appropriate response to the results may have limited impact on patient outcomes . Further, the cost-effectiveness of screening may be undermined by false positives , although this limitation may be mitigated by the staging approach.
Reorienting the binary diagnostic model currently in use towards a more nuanced hybrid categorical-dimensional staged model can address several barriers facing global mental health. The first is reducing the potential numbers of people who need clinical interventions. Given that the population point prevalence of depression, based on the binary system, is estimated at about 5% of the adult population —translating to over 200 million people globally—few countries, particularly in the global south, have a health care system that can cope with the massive numbers of people who would meet the current diagnostic criteria. The staged model would dramatically reduce the estimates of the numbers of persons with depressive symptoms who need clinical interventions, offering a better prospect of reducing the treatment gap for disorders both by reducing the denominator of this fraction and by focusing the energies of the health care system to detect and treat these disorders.
It is becoming increasingly commonplace, even trendy perhaps, to talk about depression, not least due to the growing number of celebrities, from Bruce Springsteen to Deepika Padukone, disclosing their personal experiences of struggle and recovery. However, to move this discourse beyond celebrities to the general population, in particular amongst those experiencing social adversities who are disproportionately affected by depressive symptoms, we need to move from a binary classification to a staged model that explicitly recognizes the dimensional nature of this condition. Such a revised framing has potential utility for diverse audiences, including scientists, policy makers, patients, and practitioners, and offers a framework for consensus between diverse disciplines, between the clinical and public health communities, and between professionals and civil society on how to talk sensibly about depression, in one voice. There is no doubt whatsoever that we must talk about depression more openly, but we must ensure that people experiencing depressive symptoms are always at the heart of the discourse.