The ‘global burden’
The ICD and DSM classifications have continued to consider mental illnesses as ‘disorders’. Indeed, the World Health Organization’s ‘Global Burden of Disease Study 2010’ (the findings from which were released in 2012), indicated that a substantial proportion of the world’s ‘disease’ burden came from mental, neurological and substance use disorders: 10.4% of global disability-adjusted life years (DALYS), 2.3% of global years lost to premature mortality (YLLs) and 28.5% of global years lived with disability (YLDs). Mental disorders accounted for the largest proportion of DALYs (Whiteford et al., 2015). Anxiety and depressive disorders made a significantly disproportionate contribution to the overall burden of ‘disease’ – the figures were striking, as detailed below. (See also Section 4.4 and Box 9.)
In their analysis published in 2015, Whiteford and colleagues estimated that anxiety disorders (mild, moderate and severe states) accounted for more than 272 million cases (derived from estimates of point prevalence, i.e. the number of new and pre-existing cases at a specified point in time), close behind major depressive disorder (at 298 million). These figures were far greater than for other mental, neurological and substance use estimates (alcohol dependence being next in the order at ~95 million) with the exception of tension-type headaches and migraine, which topped the billion mark for prevalence estimates (Table 1 in Whiteford et al., 2015). After standardising for age, major depressive disorder and anxiety disorders had the highest DALYs with rates for women consistently higher than for men (Table 2 in Whiteford et al., 2015). Aggregating the DALYs across all countries, gender and age groups for the 2010 data (Table 3 in Whiteford et al., 2015) identified major depressive disorder as representing 2.5% (63.2 million DALYs) and anxiety disorders 1.1% (26.8 million DALYs) of all cases of the global burden of disease, and 24.5% and 10.4% respectively of the burden of DALYs attributable solely to ‘mental, neurological and substance use’ – the greatest proportions by far in either category amongst the conditions listed.
Whiteford and colleagues (2015) noted that 'although these disorders exist in all countries, cultures also influence their development and presentation' and that 'the predominantly Western-based definitions of mental, neurological and substance-use disorders can be in conflict with cultural contexts, leading to challenges in assembling data on global epidemiology' (Whiteford et al., 2015). Clearly then, the cultural context in which a diagnosis is made is an important factor for epidemiological studies based on diagnostic classifications. Fortunately, this is acknowledged in DSM-5. Box 4 lists some of the significant changes from the previous edition of the DSM that are relevant to anxiety.
Box 4 Major changes from DSM-IV-TR to DSM-5 focusing on anxiety disorders
(American Psychiatric Association, 2013)
‘Culture’ is discussed more explicitly to bring greater attention to cultural variations in symptom presentations.
DSM-5 has moved to a nonaxial documentation of diagnosis (formerly Axes I, II, and III), with separate notations for important psychosocial and contextual factors (formerly Axis IV) and disability (formerly Axis V). This approach is consistent with WHO and ICD guidance to consider the individual’s functional status separately from their diagnoses/symptom status.
‘Social Phobia’ is now termed ‘Social Anxiety Disorder’.
‘Panic Disorder’ and ‘Agoraphobia’ have been unlinked and each now has its own separate criteria (on the basis that many patients experience agoraphobia without panic symptoms).
‘Separation anxiety disorder’ and ‘selective mutism’ are now classified as anxiety disorders (instead of Disorders of Infancy, Childhood or Adolescence, which has been eliminated).
Age criteria for Separation Anxiety Disorder have been changed to allow onset after age 18, with a duration criterion added of ‘typically lasting 6 months or more’.
For Agoraphobia, Specific Phobia, and Social Anxiety Disorder, the 6 month duration criterion has been extended to all ages (formerly just individuals under age 18) to minimise overdiagnosis of transient fears. The anxiety must be out of proportion to the actual danger or threat, but the requirement that individuals over age 18 years recognise their anxiety as excessive or unreasonable has been eliminated.
Panic attack descriptors have changed to identify 'unexpected and expected' panic attacks. Panic attacks function as a prognostic factor for severity of diagnosis, course, and comorbidity across many anxiety and other disorders, and thus can be listed as a specifier that is applicable to all DSM-5 disorders.