Depression. Aaron T. Beck, M.D.

conclusions could be drawn. The following statistics for the decade of peak incidence may serve as a rough guide: 20–30, Kraepelin¹; 30–39, Stenstedt,¹² Cassidy et al.,¹³ Ayd¹⁴; 45–55, Rennie⁵; 50 and older, Lundquist.⁶

Remission and Chronicity

      There was considerable variation among the authors on the proportion of patients remaining chronically ill following the onset of depressive illness. It is difficult to make comparisons among the various studies because different diagnostic criteria were used, the definition of chronicity varied, the periods of observation varied, and in many studies, no distinction was made between those who became chronic after the first attack and those who became chronic only after multiple attacks.

      The relatively well-designed retrospective study by Rennie indicated that approximately 3 percent were found on long-term follow-up to be chronically ill. Kraepelin reported that 5 percent of his cases became chronic. Lundquist reported that 79.6 percent of the depressives recovered completely from the first attack. Age of onset was a factor: the remission rate ranged from 92 percent for patients less than 30 years old to 75 percent in the 30–40 age group. It is probable that his percentages are lower than those of the others because of his more stringent definition of complete remission.

      Astrup et al.¹¹ divided their group of manic-depressive patients into the categories of “chronic,” “improved,” and “recovered.” Of the 70 “pure” manic depressives, 6 (8.6 percent) were still chronically ill at the time of follow-up. The majority had recovered completely, and a minority showed residual “instability” and were classified as improved. (Precise figures for the improved and recovered categories are not available because of the lumping together of manic-depressive and schizoaffective patients.) The follow-up period was five years or more.

      It is noteworthy that a patient may have an initial manic or depressive episode from which she or he recovers completely and, after a long symptom-free interval, may relapse into a chronic state. Rennie reported the case of a patient who had an initial episode of mania followed by depression, the entire cycle lasting about a year. He was symptom-free for 23 years afterward and then lapsed into a state of manic excitement lasting 22 years.

      Kraepelin¹ indicated that a patient may have chronic depression of many years’ duration and still have a complete remission. He presented an illustrative case (p. 143) with a single attack lasting 15 years, from which the patient had made a complete remission.

Remission from Dysthymic Disorder

      More recently, study of chronic, low-grade depression—referred to as “dysthymic disorder”—was reported by Klein et al.¹⁵ The diagnostic criteria for dysthymic disorder are listed in Table 3-1. (More detailed information on the classification of the various mood disorders is provided in Chapter 4.)

      To study recovery in dysthymic disorder, Klein et al.¹⁵ used a prospective design and a naturalistic 5-year follow-up. Participants were 86 outpatients with early-onset dysthymic disorder, and 39 outpatients with episodic major depressive disorder. Follow-ups were conducted at 30 and 60 months. Only about half (52.9 percent) of the patients with dysthymic disorder had recovered after five years. Over an average of 23 months of observation, the relapse rate for this disorder was 45.2 percent.

      Klein compared patients with dysthymic disorder and those with episodic major depressive disorder. The former spent 70 percent of the time over the 5-year follow-up meeting the criteria for a mood disorder; the latter spent less than 25 percent of the time meeting mood disorder criteria.

TABLE 3-1. Diagnostic Criteria for Dysthymic Disorder

A)	Depressed mood for most of the day, for more days than not, as indicated by subjective account or observation by others, for at least 2 years. Note: In children and adolescents, mood can be irritable and duration must be at least 1 year.
B)	Presence, while depressed, of two (or more) of the following:
	(1) poor appetite or overeating (2) insomnia or hypersomnia (3) low energy or fatigue (4) low self-esteem (5) poor concentration or difficulty making decisions (6) feelings of hopelessness
C)	During the 2-year period (1 year for children or adolescents) of the disturbance, the person has never been without the symptoms in Criteria A and B for more than 2 months at a time.
D)	No Major Depressive Episode has been present during the first 2 years of the disturbance (1 year for children and adolescents); i.e., the disturbance is not better accounted for by chronic Major Depressive Disorder, or Major Depressive Disorder, in Partial Remission.
E)	There has never been a Manic Episode, Mixed Episode or Hypomanic Episode, and criteria have never been met for Cyclothymic Disorder.
F)	The disturbance does not occur exclusively during the course of a chronic Psychotic Disorder, such as Schizophrenia or Delusional Disorder.
G)	The symptoms are not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition (e.g., hypothyroidism).
H)	The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.

      Those with dysthymia had more symptoms, lower functioning, and higher probability of attempting suicide and being hospitalized than those with major depressive disorder. By the end of the 5-year follow-up, 94.2 percent (81 of 86) of the dysthymic disorder group had at least one lifetime major depressive episode. This figure includes the 77.9 percent (67 of 86) of this group who had already experienced superimposed major depression at the onset of the study. Among those patients with dysthymic disorder who had not reported a major depressive episode before the study (19 of 86), the estimated risk of having a first lifetime major depressive episode was 76.9 percent (14 of 19). Overall, these findings suggest that dysthymic disorder is a chronic, severe condition with a high risk of relapse.¹⁵

Remission from Functional Impairments

      Buist-Bouwman et al.¹⁶ addressed the question of whether people who remit from a major depressive episode also recover from functional impairments. These impairments were assessed by the Short-Form-36 Health Survey and included things like physical functioning, vitality, pain, social functioning, and general health.

      The study used data from the Netherlands Mental Health Survey and Incidence Study, and depression was diagnosed using the hierarchical rules of DSM-III-R. Those who suffered major depressive episodes during the course of psychotic or bipolar disorders were excluded. A total of 165 people were included in the study.

      Results showed that 60 to 85 percent of the respondents did better or showed no change in functioning after recovery from depression, compared to their functioning prior to depression. Still, the average levels of functioning after depression were lower compared to people from a nondepressed sample, people who had never been depressed. Those who suffered from substance abuse and anxiety disorders, physical illness, and low social support showed poorer functioning. The authors suggested that a limitation of the study was that nonprofessional interviewers were used to determine the diagnosis of depression by structured interviews, and functioning was obtained by self-report.

Duration

      Some idea of the average or expected duration of an episode of depression is obviously important so that the physician can adequately prepare the patient and family psychologically and give them a basis for making decisions about