Journal of Affective Elsevier
Disorders, 19 (1990) 87-98
87
JAD 00705
Recurrent brief depression: a new subtype of affective disorder J. Angst I, K. Merikangas
*, P. Scheidegger
’
and W. Wicki 1
’ Research Department, Psychiatric University Hospital, 8029 Zurich, Switzerland and 2 Yale University School of Medicine, Department
of Psychiatry,
Genetic Epidemiology
Research
Unit, New Haven, CT 06510-3223,
U.S.A.
(Received 31 October 1988) (Revision received 6 November 1989) (Accepted 13 November 1989)
Summary This paper presents the diagnostic criteria for a new subtype of affective disorder, recurrent brief depression (RBD). Data from a prospective longitudinal cohort of young adults from the general population of Zurich, Switzerland, showed that a substantial proportion met all of the criteria for major depression in current diagnostic systems except duration. The validity of the subtype of RBD was examined according to clinical manifestations, severity, longitudinal course, and family history. RBD was found to be similar to major depressive disorder (MDD) on most of the indicators of validity including symptomatology, association with somatic and psychiatric disorders, age at onset, family history, longitudinal course and levels of impairment, except duration of depressive episodes. This suggests that RBD constitutes a valid subtype of affective disorder. The major implications of these findings are that both recurrence and duration should be considered in developing diagnostic thresholds for depression and in assessing the severity of affective disorders.
Key words: Recurrent brief depression; Major depressive disorder; Validity; Prospective cohort study
Introduction Over the past decades, a number of definitions of major depression have been proposed in standardized diagnostic systems in American psychiatry (Feighner et al., 1972; Spitzer et al., 1978; American Psychiatric Association, 1980, 1987).
Address for correspondence: partment, Psychiatric University Zurich, Switzerland. 0165-0327/90/$03.50
J. Angst, M.D., Research DeHospital, P.O. Box 68, 8029
0 1990 Elsevier Science Publishers
Although the essential components of depression, which include a change in mood for a particular duration accompanied by a specified number of symptoms, have remained stable, different diagnostic thresholds have been used. These definitions were developed from data from clinical samples of depressed patients, primarily from inpatient settings. The utility of these definitions for samples selected from non-treatment settings has not been well established. Although an acceptable degree of reliability has been achieved for most of these definitions, par-
B.V. (Biomedical
Division)
88 titularly those which derive from structured clinical instruments, the validity of these constructs has not been adequately evaluated. This is especially illustrated in general population surveys which have shown that the majority of persons had not been treated for depressive syndromes (Shapiro et al., 1984). On the other hand, application of the current diagnostic criteria for major depression in a representative sample of young adults in Zurich, Switzerland resulted in a substantial number of persons who had received treatment for depression but failed to meet the diagnostic criteria for major depression listed in Table 1. This paper examines the application of a new concept of depression characterized by recurrence of a depressive syndrome of shorter duration than that employed in well-known diagnostic systems, termed recurrent brief depression (RBD) (Angst and Dobler-Mikola, 1985). It was previously shown that only about 50% of a 20-year-old cohort of the normal population who had been treated for depression met diagnostic criteria for major depressive disorder or dysthymia (Angst, 1988). Application of the diagnostic criteria for RBD resulted in more than two thirds of the undiagnosed cases receiving a diagnosis of RBD. The validity of this syndrome will be examined systematically according to the criteria of Robins and Guze (1970) which include the following types of information: inclusion criteria, delimitation from other disorders, family history, and longitudinal course. Methods Subjects The subjects for the study are those of the Zurich Study, a longitudinal epidemiologic cohort study of young adults in Zurich, Switzerland (Angst et al., 1984). A cohort of 292 males and 299 females aged 19-20 from the Canton of Zurich in Switzerland was selected according to scores on the 90-item Hopkins Symptom Checklist (SCL-90R) (Derogatis, 1977) in 1978. Subjects with high scores (i.e., above the 85th percentile) comprised two thirds of the sample. The remaining subjects were randomly selected from those who scored below the 85th percentile on the SCL-90. There were four waves of interviews: 1979, 1981, 1986,
Screening:
Questionnaire
1979
Interview
1980
Questionnaire
1981
Interview
1986
Interview
Interview
1988
Fig. 1. Design of the Zurich
study
and 1988. All 591 subjects were interviewed in 1979, of whom 456 were reinterviewed in 1981; 457 subjects, some of whom did not participate in 1981, were re-interviewed in 1986. Ninety percent of the subjects who participated in 1986 were interviewed again in 1988. Additionally, the subjects were contacted by mail in 1980. The dropout rate after the third interview wave, 7 years after the first interview, was 23%. An overview of the design of the study and the participation rates are depicted in Fig. 1. Two subsamples according to the number of interviews were examined in the present analyses: a sample of 457 subjects who were interviewed in both 1979 and 1986 (225 males, 232 females); and a subset of the latter (356 subjects: 164 males, 192 females), who were interviewed at all four times. The total duration of observation of the cohort is now 10 years. Because the 1988 interview was completed so recently, data in the current report will be limited to the major diagnostic categories of the longitudinal cohort. More comprehensive assessment of the features of RBD in the 1988 sample will be presented in subsequent reports. Diagnostic assessment The diagnostic instrument employed in this study was. the SPIKE, a semi-structured instrument which was developed for epidemiological
89 TABLE
1
CRITERIA
FOR DEPRESSION Feighner
Dysphoric mood Duration (weeks) Symptoms Impairment Recurrence Structured instrument a Includes
RDC
DSM-III
DSM-III-R
RBD
+
+
+
2
Major
Minor
+ 4
+ 2
5/g
5/S
+ 1 2/16
IlO
yes
IlO
4/S no
no
no
no
“0
2 5/9 no no
Renard
SADS
SADS
DIS
SCID
Disorders, 19 (1990) 87-98
87
JAD 00705
Recurrent brief depression: a new subtype of affective disorder J. Angst I, K. Merikangas
*, P. Scheidegger
’
and W. Wicki 1
’ Research Department, Psychiatric University Hospital, 8029 Zurich, Switzerland and 2 Yale University School of Medicine, Department
of Psychiatry,
Genetic Epidemiology
Research
Unit, New Haven, CT 06510-3223,
U.S.A.
(Received 31 October 1988) (Revision received 6 November 1989) (Accepted 13 November 1989)
Summary This paper presents the diagnostic criteria for a new subtype of affective disorder, recurrent brief depression (RBD). Data from a prospective longitudinal cohort of young adults from the general population of Zurich, Switzerland, showed that a substantial proportion met all of the criteria for major depression in current diagnostic systems except duration. The validity of the subtype of RBD was examined according to clinical manifestations, severity, longitudinal course, and family history. RBD was found to be similar to major depressive disorder (MDD) on most of the indicators of validity including symptomatology, association with somatic and psychiatric disorders, age at onset, family history, longitudinal course and levels of impairment, except duration of depressive episodes. This suggests that RBD constitutes a valid subtype of affective disorder. The major implications of these findings are that both recurrence and duration should be considered in developing diagnostic thresholds for depression and in assessing the severity of affective disorders.
Key words: Recurrent brief depression; Major depressive disorder; Validity; Prospective cohort study
Introduction Over the past decades, a number of definitions of major depression have been proposed in standardized diagnostic systems in American psychiatry (Feighner et al., 1972; Spitzer et al., 1978; American Psychiatric Association, 1980, 1987).
Address for correspondence: partment, Psychiatric University Zurich, Switzerland. 0165-0327/90/$03.50
J. Angst, M.D., Research DeHospital, P.O. Box 68, 8029
0 1990 Elsevier Science Publishers
Although the essential components of depression, which include a change in mood for a particular duration accompanied by a specified number of symptoms, have remained stable, different diagnostic thresholds have been used. These definitions were developed from data from clinical samples of depressed patients, primarily from inpatient settings. The utility of these definitions for samples selected from non-treatment settings has not been well established. Although an acceptable degree of reliability has been achieved for most of these definitions, par-
B.V. (Biomedical
Division)
88 titularly those which derive from structured clinical instruments, the validity of these constructs has not been adequately evaluated. This is especially illustrated in general population surveys which have shown that the majority of persons had not been treated for depressive syndromes (Shapiro et al., 1984). On the other hand, application of the current diagnostic criteria for major depression in a representative sample of young adults in Zurich, Switzerland resulted in a substantial number of persons who had received treatment for depression but failed to meet the diagnostic criteria for major depression listed in Table 1. This paper examines the application of a new concept of depression characterized by recurrence of a depressive syndrome of shorter duration than that employed in well-known diagnostic systems, termed recurrent brief depression (RBD) (Angst and Dobler-Mikola, 1985). It was previously shown that only about 50% of a 20-year-old cohort of the normal population who had been treated for depression met diagnostic criteria for major depressive disorder or dysthymia (Angst, 1988). Application of the diagnostic criteria for RBD resulted in more than two thirds of the undiagnosed cases receiving a diagnosis of RBD. The validity of this syndrome will be examined systematically according to the criteria of Robins and Guze (1970) which include the following types of information: inclusion criteria, delimitation from other disorders, family history, and longitudinal course. Methods Subjects The subjects for the study are those of the Zurich Study, a longitudinal epidemiologic cohort study of young adults in Zurich, Switzerland (Angst et al., 1984). A cohort of 292 males and 299 females aged 19-20 from the Canton of Zurich in Switzerland was selected according to scores on the 90-item Hopkins Symptom Checklist (SCL-90R) (Derogatis, 1977) in 1978. Subjects with high scores (i.e., above the 85th percentile) comprised two thirds of the sample. The remaining subjects were randomly selected from those who scored below the 85th percentile on the SCL-90. There were four waves of interviews: 1979, 1981, 1986,
Screening:
Questionnaire
1979
Interview
1980
Questionnaire
1981
Interview
1986
Interview
Interview
1988
Fig. 1. Design of the Zurich
study
and 1988. All 591 subjects were interviewed in 1979, of whom 456 were reinterviewed in 1981; 457 subjects, some of whom did not participate in 1981, were re-interviewed in 1986. Ninety percent of the subjects who participated in 1986 were interviewed again in 1988. Additionally, the subjects were contacted by mail in 1980. The dropout rate after the third interview wave, 7 years after the first interview, was 23%. An overview of the design of the study and the participation rates are depicted in Fig. 1. Two subsamples according to the number of interviews were examined in the present analyses: a sample of 457 subjects who were interviewed in both 1979 and 1986 (225 males, 232 females); and a subset of the latter (356 subjects: 164 males, 192 females), who were interviewed at all four times. The total duration of observation of the cohort is now 10 years. Because the 1988 interview was completed so recently, data in the current report will be limited to the major diagnostic categories of the longitudinal cohort. More comprehensive assessment of the features of RBD in the 1988 sample will be presented in subsequent reports. Diagnostic assessment The diagnostic instrument employed in this study was. the SPIKE, a semi-structured instrument which was developed for epidemiological
89 TABLE
1
CRITERIA
FOR DEPRESSION Feighner
Dysphoric mood Duration (weeks) Symptoms Impairment Recurrence Structured instrument a Includes
RDC
DSM-III
DSM-III-R
RBD
+
+
+
2
Major
Minor
+ 4
+ 2
5/g
5/S
+ 1 2/16
IlO
yes
IlO
4/S no
no
no
no
“0
2 5/9 no no
Renard
SADS
SADS
DIS
SCID
