Chapter 8 David S. Baldwin1 and Julia M. Sinclair2 1 Professor of Psychiatry and Head of Mental Health Group, Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, UK 2 Senior Lecturer in Psychiatry, Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, UK Psychiatrists and general practitioners should be aware of the need to distinguish between depressive symptoms, syndromes, and disorders. This awareness arises largely from observations in clinical practice, but also comes from the development of operationalized criteria for diagnosing depression, from early initiatives such as the Feighner criteria [1] and the research diagnostic criteria [2], to current schemes including the clinical descriptions included within the ICD-10 system [3] and the DSM-5 classification [4]. The various diagnostic systems have employed differing definitions for depressive disorders; for example, the criteria for “major” depression have varied with respect to the number and severity of symptoms, the duration of illness, the degree of personal distress, and the functional consequences of the condition (Table 8.1). Table 8.1 Diagnostic criteria for “major” depressive disorders. *ICD-IO depressive episode (F32) requires presence of at least two of three “typical” symptoms (depressed mood, loss of interest and enjoyment, and reduced energy). †DSM-IV and DSM-5 major depressive episode requires presence of at least one of two symptoms (depressed mood, loss of interest or pleasure). ‡ICD-IO depressive episode can be diagnosed earlier than 2 weeks, if symptoms are unusually severe and of rapid onset. §Refers to minimum number of symptoms required for diagnosis. ¶Recurrence required to make diagnosis. Psychiatrists see a poorly representative sample of the wider population of depressed patients, largely those who are most severely ill, with treatment-resistant symptoms, and with co-morbid disorders [5]. As a result, the definitions of depression derived from samples of psychiatric inpatients and outpatients may have limited relevance in primary care settings, where many depressed patients do not fulfill “accepted” criteria for major depressive episodes, because their illness is too mild, or too short, or not especially impairing. To address this problem, the more recent classifications have described a number of parallel depressive conditions, to include these important groups of depressed patients who could not otherwise be allocated a diagnosis. For example, the ICD-10 includes dysthymia to describe a persistent (at least 2 years) but mild depressive state; by contrast the DSM-5 uses “persistent depressive disorder” to describe long-lasting depressive illnesses previously recognised as either chronic but severe (chronic major depression), or chronic but mild (dysthymic disorder). Both ICD-10 and DSM-5 include a description of recurrent brief depression (RBD) within the broad group of depressive disorders. Recurrent brief depression is not a new disorder, created to medicalize unhappiness or to satisfy a pressure for financial reimbursement. Short and mild depressive and hypomanic states were included within the broad category of manic-depressive illness by Kraepelin in 1889 [6], and transient states of severe affective disturbance were described 100 years ago [7, 8]. A condition similar to current conceptions of RBD was outlined shortly afterward [9] and was regarded as being particularly important in primary medical care. Patients were described as experiencing depressive episodes that were short-lived (lasting from a few hours to a few days), but that tended to recur frequently over the course of many years. Further accounts emphasized both the personality characteristics of affected individuals and the increased risk of suicide [10, 11]. However, despite its early recognition and readily apparent clinical importance, the syndrome of RBD was not subject to detailed investigation over the next 40 years. The research diagnostic criteria [2] included a category for diagnosing depressions that were short-lived and intermittent, but classified them as a form of minor depression, indicating that it was a mild disorder, of lesser clinical importance. Many studies of the prevalence of mild and short-lived affective disturbances in the general population have been performed, but there have been relatively few longitudinal studies of their incidence and longer-term course. The Zurich study [12], a prospective epidemiological investigation of depressive, neurotic, and psychosomatic syndromes, was the first modern investigation to lead to a renewed and heightened awareness of the clinical importance of short-lived (brief) but highly recurring and often markedly severe episodes of depression within the general population. In this influential investigation, a representative sample of (initially) young people from the Swiss Canton of Zurich has been interviewed repeatedly over the course of 35 years. Details of the study design and characteristics of the sample have been described elsewhere [12]. Participants within the cohort have been examined on many separate time points, using a specially designed interview schedule known as the SPIKE [13]. This interview covers a range of psychological and somatic syndromes, each of which is assessed according to the presence and number of symptoms; their duration, frequency, and recurrences; any treatment that has been received; and the presence of any family history. Using SPIKE-derived data, the early interview phases showed that approximately one-half of the interviewees who had received treatment for depression did not fulfil the then-current DSM-III [14] criteria for major depression. These patients tended to experience depressive episodes that were short-lived but otherwise indistinguishable from major depressive episodes. In addition, around half of this group of patients experienced brief depressions that recurred at least monthly, and were associated with substantial social and occupational impairment. The early phases of the study revealed that approximately 5.0–10.0 percent of the general population experience intermittent brief depressions within any 1 year [15], and the period prevalence over the first 10 years (when the sample was aged between 20 and 30 years) was approximately 11 percent. The findings from this study subsequently led to the development of proposed diagnostic criteria for RBD. The Zurich criteria, first delineated by Angst and colleagues [16, 17], stipulated that RBD is akin to DSM-III major depression with respect to symptoms, and similar to research diagnostic criteria [2] with respect to occupational impairment. However, RBD was distinguished from those two conditions, in requiring that depressive episodes last less than 2 weeks, but recur at least monthly over 1 year (Table 8.2). Broadly similar criteria for RBD are included within the ICD-10 and DSM-5: depressive episodes must last less than 14 days and should recur approximately monthly for at least 1 year. ICD-10 lists RBD within the group of “other recurrent mood [affective] disorders” [F38.1]. The DSM-5 places RBD within the group of “other specified depressive disorder” (311) (Table 8.3). Table 8.2 Recurrent brief depression: the Zurich study criteria (from Angst and Dobler-Mikola [16]). Table 8.3 Recurrent brief depression in ICD-10 and DSM-5. Further support for the concept of RBD came from the findings of the World Health Organization study of psychological disorders in primary care [18]. From a group of 9697 consecutive general practice attenders, a sample of 1911 underwent a structured psychiatric interview. RBD was found to have a point prevalence of 3.7 percent, women being more commonly affected, and was seen to be a highly co-morbid condition, especially with major depression and generalized anxiety disorder, with a high (14 percent) lifetime rate of suicidal behaviour. Subsequent studies provided further support. For example, a sample of 300 primary care patients in Germany was assessed with respect to the number and duration of depressive symptoms: brief depression was diagnosed according to Zurich criteria, and found to have a point prevalence of 30 percent, more strictly-defined RBD having a point prevalence of 5.4 percent, the validity of brief depression appearing greater than that of “minor” depression (characterised by the presence of 3 or 4 depressive symptoms) [19]. Another study, performed in rural and urban Sardinia, and using a structured clinical interview, found that RBD had a lifetime prevalence of 6.9 percent, was frequently co-morbid with other mental disorders (particularly major depression), and associated with an increased risk of suicidal behaviour (9.1 percent), this being most marked in those with both major depression and RBD [20]. The Zurich study findings indicate that RBD is as stable a diagnosis as major depression: approximately 20 percent of people with RBD develop major depressive episodes when followed up, and a similar proportion show a change in the opposite direction (Angst, [15, 17]). The term combined depression has been suggested as suitable to describe the group of patients whose depressive episodes vary in length, typically with prolonged (i.e., more than 2 weeks) episodes becoming “superimposed” on a background of intermittent brief depressive episodes. It is therefore possible to compare individuals with RBD alone to those individuals with major depression alone, and to those with combined depression [17].
Recurrent brief depression: “This too shall pass”?
Introduction
Feighner et al. [1]
RDC Spitzer et al. [2]
DSM-III APA 1980
DSM-III-R APA 1987
ICD-10 WHO [3]
DSM-IV APA 1994
DSM-5 APA [4]
major
minor
Low or dysphoric mood
+
+
+
+
+
–*
–†
–†
Duration (weeks)
4
2
1
2
2
2‡
2
2
Symptoms§
5/8
5/8
2/16
4/8
5/9
5/9
5/9
5/9
Impairment
No
Yes
No
No
No
Yes
Yes
Yes
Recurrence¶
No
No
No
No
No
No
No
No
Development of the concept of recurrent brief depression
Arrival of modern diagnostic criteria: The Zurich study
ICD-IO F38.I0 Recurrent brief depressive disorder
Recurrent brief depressive episodes, occurring approximately once a month over the past year. The individual depressive episodes all last less than 2 weeks (typically 2–3 days, with complete recovery) but fulfill the symptomatic criteria for mild, moderate, or severe depressive episode (F32.0, F32.1, F32.2).
Differential diagnosis
In contrast to those with dysthymia (F34.1), patients are not depressed for the majority of the time. If the depressive episodes occur only in relation to the menstrual cycle, F38.8 should be used with second code for the underlying cause (N94.8, other specified conditions associated with female genital organs and menstrual cycle).
DSM-5 311 Other specified depressive disorder
Recurrent brief depression: The concurrent presence of depressed mood and at least four other symptoms of depression for 2–13 days at least once per month (not associated with a menstrual cycle) for at least 12 consecutive months in an individual whose presentation has never met criteria for any other depressive disorder or bipolar disorder and does not currently meet active or residual criteria for any psychotic disorder.
Further epidemiological observations