Elsevier

The Lancet Psychiatry

Volume 3, Issue 2, February 2016, Pages 171-178
The Lancet Psychiatry

Personal View
Estimating the true global burden of mental illness

https://doi.org/10.1016/S2215-0366(15)00505-2Get rights and content

Summary

We argue that the global burden of mental illness is underestimated and examine the reasons for under-estimation to identify five main causes: overlap between psychiatric and neurological disorders; the grouping of suicide and self-harm as a separate category; conflation of all chronic pain syndromes with musculoskeletal disorders; exclusion of personality disorders from disease burden calculations; and inadequate consideration of the contribution of severe mental illness to mortality from associated causes. Using published data, we estimate the disease burden for mental illness to show that the global burden of mental illness accounts for 32·4% of years lived with disability (YLDs) and 13·0% of disability-adjusted life-years (DALYs), instead of the earlier estimates suggesting 21·2% of YLDs and 7·1% of DALYs. Currently used approaches underestimate the burden of mental illness by more than a third. Our estimates place mental illness a distant first in global burden of disease in terms of YLDs, and level with cardiovascular and circulatory diseases in terms of DALYs. The unacceptable apathy of governments and funders of global health must be overcome to mitigate the human, social, and economic costs of mental illness.

Introduction

Mental health is defined by WHO as “a state of well-being in which every individual realizes his or her own potential, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a contribution to her or his community”.1 This state, however, is disrupted in one of every three individuals—or more—during their lifetimes.2, 3

Worldwide the magnitude of mental illness has been emphasised by studies on the global burden of disease.4 Yet, in spite of the very considerable burden and their associated adverse human, economic, and social effects, global policy makers and funders have so far failed to prioritise treatment and care of people with mental illness.5, 6 Consequently, people with mental illness worldwide are largely neglected.6 Pervasive stigma and discrimination7, 8 contributes, at least in part, to the imbalance between the global burden of disease attributable to mental disorders, and the attention these conditions receive. Stigma, embodied in discriminatory social structures, policy, and legislation, produces a disparity between services geared to physical health and mental health, with lower availability, accessibility, and quality of services for the latter.9

Globally, rapid economic, demographic, and epidemiological transitions mean a growth in populations that are living longer, but with greater morbidity and disability.10, 11, 12, 13 Mental disorders are a major driver of the growth of overall morbidity and disability globally.14, 15

Five types of mental illness appear in the top 20 causes of global burden of disease (GBD): major depression (second), anxiety disorders (seventh), schizophrenia (11th), dysthymia (16th), and bipolar disorder (17th) were leading causes of years lived with disability (YLDs) in 2013.11 In this context, this Personal View aims to: offer a constructive critique of current estimates of GBD related to mental illness; argue that in aggregate mental illness is underestimated; and explore an alternative approach to produce more realistic GBD estimates of mental disorders worldwide. We do not propose a different nosology of disorders, but aim to better gauge the disease burden of mental illness. An important benefit of a new GBD estimation is to inform prioritisation of health needs and resource allocation, so our aim is to provide decision makers, who rely on specialists to design and implement policies, with a new set of assumptions and tools to produce more accurate estimations using existing data.

Section snippets

Burden of mental illness: measurement challenges

We argue that the burden of mental illness has been underestimated due to five reasons: the overlap between psychiatric and neurological disorders; the grouping of suicide and behaviours associated with self-injury as a separate category outside the boundary of mental illness; the conflation of all chronic pain syndromes with musculoskeletal disorders; the exclusion of personality disorders in mental illness disease burden calculations; and inadequate consideration of the contribution of severe

The psychiatric–neurological interface

Traditionally, disorders both affecting the central nervous system and producing mental disorders were divided between psychiatric and neurological conditions: if the syndrome had a clear neuroanatomical or neurophysiological basis it was considered neurological; if not, it was deemed psychiatric. However, this dual distinction has more to do with professional areas of competence than scientific logic. For example, schizophrenia, considered a psychiatric disorder, affects the brain's anatomy

Categorising suicide and intentional self-harm

In 2013, mental illness accounted for 21·2% of the YLDs worldwide—higher than any other group of conditions.11 However, using the composite measure disability-adjusted life-years (DALYs), the burden of mental illness accounted for 7·1%, ranking fifth overall in terms of GBD.18, 19 The gap between the burden of mental illness as measured by years lived with disability and that measured by DALYs is explained by the fact that DALYs underestimate mental illness mortality due to suicide, to the

Chronic pain syndromes

Musculoskeletal conditions were the second major cause of YLDs11 and seventh ranked cause of DALYs in 2013 globally.26 These conditions include anatomically based disorders (such as osteoarthritis and rheumatoid arthritis), and also syndromes and symptoms (eg, fibromyalgia, low back pain) characterised by pain but without specific anatomical correlates. The allocation of the burden corresponding to these syndromes in total to the musculoskeletal aggregation is problematic because: a substantial

Including people with personality disorders

Personality disorders are common (4–15% in point prevalence community surveys)27 and when severe impose a substantial burden both at personal, family, community, and population levels. People with personality disorders have shorter life expectancy and higher comorbidity with other general and mental illnesses than the general population.27 However, due to the inconsistent quality of the evidence, personality disorders were not included in GBD 2013 estimates within the overall category of mental

Premature mortality

People with severe mental illness have up to 60% higher chances of dying prematurely from non-communicable diseases29 that are neglected because of the underlying mental condition. They die 10–20 years younger than their peers in high-income countries, and 30 years younger in low-income countries.30, 31, 32 Charlson and colleagues33 estimate that up to 8% of years of life lost globally corresponded to excess deaths due to mental health-related conditions including dementia, epilepsy, and

Revising DALYs (2013) estimates for mental illness

For the reasons set out above we propose that when estimating disease burden, certain neurological syndromes (ie, the dementias, epilepsy, tension-type headache, and migraine) should be aggregated within the overall category of mental illness. This adjustment would move the total rank of mental illnesses in the GBD tables from fifth to third place overall, accounting for 9·8% of DALYs globally (table 1). Repositioning all DALYs related to self-harm from the category of injuries to mental health

Revising YLDs (2013) estimates for mental illness

In 2013, mental illness accounted for 21·2% of global YLDs, 3·5 times greater than the disability associated with all infectious diseases (6·0% of YLDs), four times that for all injuries combined (5·0% of YLDs), eight times the disability associated with all cardiovascular and circulatory diseases (2·8% of YLDs), and 24 times the disability associated with all cancers (0·9% of YLDs). Musculoskeletal disorders (plus fractures and soft tissue injuries) accounted for 20·8% of total YLDs.11 As we

Disproportionately weak global response to mental illness

The global development assistance for health allocated to mental illness is far below the levels warranted by the effect of these disorders. The Millennium Development Goals (MDGs)34 prioritised child health (MDG 4), maternal health (MDG 5), and communicable diseases (MDG 6), which collectively accounted for 46·9% of DALYs 25 years ago,18 and attracted most of the development assistance for health reaching 68·0% of the $35·9 billion disbursed in 2014.35, 36 Despite the changing burden of

Discussion

The recent GBD (DALY and YLD) estimates produce an underestimate of the true effect of mental disorders on populations due to: the overlap between psychiatric and neurological disorders; the grouping of suicide and behaviours associated with self-injury as a separate category outside the boundary of mental illness; the conflation of all chronic pain syndromes with musculoskeletal disorders; the exclusion of personality disorders in mental illness disease burden calculations; and inadequate

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