Jul 5, 1996 - Beck's Depression Inventory as a screening instrument for adolescent depression in. L. Sweden: gender differences. Olsson G, von Knorring ...
Ada Psychiatr Scand 1997: 95: 277-282 Printed in UK - all rights reserved
Copyright 8 Munksgaard 1997 ACTA PSYCHIATRICA SCANDINAVICA ISSN ooo1-69oX
Beck’s Depression Inventory as a screening instrument for adolescent depression in Sweden: gender differences L
Olsson G, von Knorring A-L. Beck’s Depression Inventory as a screening instrument for adolescent depression in Sweden: gender differences. Acta Psychiatr Scand 1997: 95: 277-282. 0 Munksgaard 1997.
Beck’s Depression Inventory was administered in a study of all students aged 16-17 years in the first year of high school in a Swedish town, and was completed by 93% of them (n=2270).Cronbach’s reliability coefficient alpha was 0.89, and there were strong correlations between item scores and total scores. A diagnostic interview focused on depressive diagnosis during the last year was conducted with 88% (n=199) of all students with high scores (*16), and with the same number of controls with low scores. A depressive diagnosis was confirmed in 73% of high scorers and 13% of low scorers. The questionnaire performed better with girls than with boys. The mean score was significantly higher for girls, and the proposed limit for moderate depression (a score of 16) was reached by 14.2% of girls and 4.8% of boys. All symptoms were significantly more frequent and more severe in girls. It was found that 20% of girls and 6% of boys reported suicidal ideation. In a factor analysis the strongest factor that emerged differed between the sexes. For boys it included sadness, crying and suicidal ideation, and for girls it included failure, guilt, self-dislike and feeling unattractive, combined with 1 suicidal ideation. The gender differences are discussed.
G. Olsson, A . 4 . von Knorring Department of Child and Adolescent Psychiatry* University Hospital of Uppsala, Uppsala, Sweden
Key words: epidemiology; depression; adolescence; gender differences
Gunilla Olsson, Department of Child and Adolescent Psychiatly, University Hospital of Uppsala, S-750 17 Uppsala, Sweden Accepted for publication July 5, 1996
Introduction
Beck constructed the inventory in order to record the characteristic attitudes and symptoms of depressed adult patients (1). It was assumed that the number of symptoms and the intensity of each symptom both increase with the severity of depression. Both the reliability and the construct and concurrent validity were good (2). The aim of the inventory was to register varying degrees of depression, not to distinguish between diagnostic categories. A multiple assessment method was strongly recommended to investigate the diagnosis of depression (3). Depression among adolescents has attracted increasing interest during the last two decades. It is now clear that the core symptoms, with minor variations, are the same as those which occur in adults. The diagnostic manuals have defined depressive episodes among children and adolescents using the same symptom criteria as those for adults (4, 5). Beck’s Depression Inventory (BDI) has been widely used in adolescent populations (2). In ado-
lescent psychiatric in-patients the psychometric properties were acceptable (6), and the same observation was made among adolescent psychiatric outpatients (7); the BDI efficiently differentiated between depressed and non-depressed adolescents (8). The BDI has been used to screen for depressive symptoms in large school populations (9-13). Its psychometric properties have been evaluated in school populations of adolescents, and have been found to be acceptable (14, 15). The primary aim of this study was to evaluate the frequency and severity of depressive symptoms in Swedish mid-adolescents. The secondary aim was to investigate differences in symptomatology between boys and girls. Material and methods Population
Students in their first year of high school and aged 16-17 years were studied. Every class in all of the 277
Olsson and von Knorring nine high schools (university preparatory, creative art and vocational) of Uppsala participated. Dropouts from school, organized by a special unit, were also asked to participate. Uppsala is a university town with approximately 150 000 inhabitants, situated 70 km north of Stockholm in the central part of Sweden.
251
20
Screening
This was accomplished using the Swedish version of the original Beck’s Depression Inventory (l), which consists of self-evaluative statements arranged in 21 categories. Scores (2) from 0 to 3 are used to indicate the degree of severity. Thus the total possible score will range from 0 to 63. In order to make it more suitable for adolescents, the wording of question number 21, about libido, was changed to ‘loss of interest in the opposite sex’ (13). Screening took place at different times of the year in different schools, and was completed within 2 years. Both written and verbal information about the study was offered to the students, who filled in the questionnaires during one ordinary lesson which the whole class attended together. Those students who were absent were given another opportunity to complete the questionnaire later. Of a total of 2465 adolescents, 2300 individuals could be reached and were willing to participate in the study. Completely answered questionnaires were produced by 2270 students (1062 boys and 1208 girls), i.e. 92% of the population (90% of the boys and 94% of the girls). Of those who did not participate, about 50% belonged to the group that had dropped out of school. Diagnostic interviews
All adolescent with scores of 3.16 and one control of the same sex and in the same class were presented with the Diagnostic Interview for Children and Adolescents in the revised version according to DSM-111-R (DICA-R-A) (16). This is a structured interview that is easy to administer and not too time-consuming. It renders lifetime diagnosis of relevance for children and adolescents, as was necessary for further nososlogical studies. The interviews were conducted as soon as possible after administration of the BDI (70% within 3 months, 27% within the next 3 months and 3% within the following year). Questions about age with regard to depressive symptoms were added in order to ascertain the time of the latest depressive episode. By a thorough examination it was possible to determine whether the depressive episode occurred during the last year before the screening. The diagnosis of dys278
0
5
10
15
20 25 Total score
fig. 1. BDI in 16- to 17-year-old Swedish boys )-( (n=1210): distribution of total scores.
30
35
(n=1062) and girls
-
40
1- - -)
thymia was also re-examined in order to ensure that the symptoms were sufficiently long-lived to justify the diagnosis. Participation
Of 225 high scorers, 199 (88%) subjects were interviewed. Among the 26 subjects who did not participate, 50% refused to be interviewed, and the remaining 50% could not be reached, in most cases because they had left school. Six of these subjects belonged to the special unit for school drop-outs. The rate of non-participation was of the same magnitude among controls. Results
The mean score was 6.12k6.69. It was 7.79k7.30 for girls and 4.23f5.31 for boys, a highly significant difference ( t (2268)=13.11, P 30) were found in 1.2% of girls and 0.4% of boys. Thus high BDI scores, at different levels of cut-off, were three to four times more common in adolescent girls than boys.
BDI and adolescent depression Table 1. BDI in 16- to 17-year Swedish boys and girls: percentage frequency of symptoms at increasing levels of intensity (score of 1-3) ~
~
Boys (n=1062)
Table 2. BDI in 16- to 17year-old Swedish boys and girls: correlation of each item with total score
~~~
Girls (n=1208)
BDI item
BOI item
1
2
3
1
2
3
A. Oepressive mood B. Pessimism C. Failure 0. Dissatisfaction E. Guilt F. Punishment G. Self-dislike H. Self-accusation I. Suicidal ideation J Crying K. Irritability 1. Withdrawal M. Indecision N. Feeling unattractive 0 Work impairment P. Insomnia a. Fatigue R. Anorexia S. Weight loss 1. Health worries U. Loss of interest in the opposite sex
11 7 7 19 4 12 16 28 4 3 26 6 17 2 34 39 29 10 5 6 2
1 4 5 1 3 2 0.3 4 1 0 2 1 3 3 3 2 2 3 1 1 1
0.2 0.8 0.1 0 0.2 1.0 0.4 0.6 0.6 4.3 2.1 0.4 0.1 1.4 0.2 1.3 1.6 0.4 0.4 0.5 0.1
26 11 11 29 12 17 33 42 16 20 36 10 26 4 45 44 45 20 12 11 6
4 8 14
0.6 1.2 0.3 0.1 0.5 0.9 0.6 2.2 1.1 5.4 3.5 0.2 0.9 7.4 0.4 3.5 2.2 1.3 0.7 1.4 0
3 5 4 1.5 8 3 2 2.5 2 9 7 5 5 7 5 2 3 1
The scores for the different items varied widely (Table 1). Mild symptoms of insomnia, fatigue, work impairment, irritability and self-accusation were very common. Withdrawal from friends and loss of interest in the opposite sex were uncommon. All of the symptom categories were more frequent and more severe in girls. The item means showed highly significant differences (P0.60).For boys, feelings of failure, dissatisfaction, pessimism, depression and self-dislike showed the same high degree of correlation (Table 2).
A. B. C. D. E. F. G. H I. J. K.
L. M. N. 0. P.
a. R. S. T.
U.
Depressive mood Pessimism Failure Dissatisfaction Guilt Punishment Self-dislike Self-accusation Suicidal ideation Crying Irritability Withdrawal Indecision Feeling unattractive Work impairment Insomnia Fatigue Anorexia Weight loss Heath worries Loss of interest in the opposite sex
Total (n=2270)
Boys (n= 1062)
Girls (n= 1208)
0.69 0.60 0.66 0.64 0.63 0.56 0.65 0.60 0.63 0.58 0.52 0.44 0.57 0.51 0.57 0.54 0.60 0.50 0.31 0.49 0.39
0.61 0.62
0.70 0.58
0.65 0.64 0.58 0.55 0.60 0.54 0.53 0.51 0.52 0.42 0.52 0.46 0.59 0.54 0.59 0.50 0.29 0.42 0.35
0.65 0.63 0.64 0.57 0.65 0.60 0.67 0.59 0.51 0.46 0.56 0.49 0.54 0.53 0.58 0.48 0.29 0 51 0.41
The inter-item correlation was 0.06-0.50 (0.040.48 for boys and 0.05-0.52 for girls). In all correlations below 0.10 the item ‘losing weight’ was involved. This symptom was not very common, and could be a deliberate goal rather than a depressive symptom. A Cronbach’s reliability coefficient alpha of 0.89 (0.87 for boys and 0.88 for girls) indicates a high level of internal consistency. A factor analysis with varimax rotated factor matrix was performed for the entire sample and for the sample divided into two halves. The same factors emerged in all of the three different samples. Thus the reliability of the factor analyses was excellent. A factor matrix of >0.6 yielded four factors: depression, fatigue, withdrawal and anorexia (Table 3). The first factor differed between the sexes. For boys it was constructed by the items ‘depressed mood’, ‘crying’ and ‘suicidal ideation’. This factor accounted for 28.6% of the total variation. For girls, the first factor was a combination of ‘self-depreciation’, ‘guilt’ and ‘suicidal ideation’, and it accounted for 31.8% of the total variation. Self-depreciation was a separate factor for boys, accounting for 5.7% of the total variation. Factors 2 to 5 emerged in different orders but were almost equally strong (accounting for 5.0-6.6% of the total variation). The four factors for girls accounted for 49% of the variation and the five factors for boys accounted for 50.4%. 279
Olsson and von Knorring Table 3. BDI in 16- to 17-year-old Swedish boys and girls: factor analysis (rotated factor matrix >0.6y
Table4. BDI in 16- to 17-year-old Swedish boys and girls: depressive diagnosis (DICA-RA) during the last year in adolescents with high and low BDI scores BD121
BD1>16
Total Girls Boys . BOI item Failure Guilt Self-dislike Feeling unattractive Suicidal ideation Mood Crying
Work impairment Insomnia Fatigue
Withdrawal Loss of interest in the opposite sex
Anorexia Weight loss
Factor 1
Factor 1
0.65 0.68 0 69 0.64 0.64
0.65 0.68 0.69 0.67 0.60
-
-
Factor 1
0.67 0.62 0.67
Factor 2
Factor 3
Factor 2
0.68 0.67 0.68
0.71 0.64 0.66
0.62 0.68 0.65
Factor 3
Factor 2
Factor 5
0.72 0.75
0.70 0.76
0.67 0.79
Factor 4
Factor 4
Factor 4
0.79 0.66
0.76 '0.69
0.80 0.61 Factor 3
Self-accusation Feeling unattractive a
-
-
-
-
0.64 0.70
Factor 1 accounts for 32% of the variation (28.6% for boys; 31.8% for girls). Factors 2-5 each account for 5.0-6.6% of the variation.
An attempt was made to determine whether the responses in the BDI were sufficient to establish the diagnosis of depressive episode according to DSM criteria. A total of 14 items were referred to the nine different symptoms of depressive episode in DSM-IV (18). At least one response with a score of 2 was requested for each of five symptoms. According to this definition, 2.2% of the subjects (1.3% of the boys and 3.1% of the girls) fulfilled the criteria for major depressive episode. If responses with scores as low as 1 for each symptom were accepted, 24.7% of the subjects (15.4% of the boys and 32.8% of the girls) fulfilled the criteria. Interviews (DICA-R-A) with high scorers (216) confirmed a depressive diagnosis during the last year in 73% of cases (Table 4). Low scorers received a depressive diagnosis in 13% of cases. A higher cut-off value, at a score of 21, would increase the specificity to 81%, but would lead to the loss of 50% of the true cases. The BDI performed better for girls than for boys at both cut-off values. 280
Interviewed (n) Diagnosis (n) MDD"
Boys
Girls
Boys
Girls
Boys
Girls
43
156
43
156
16
78
4 3
8 11
20 8
77 40
11 1
38 26
16
12
65
15
75
82
Da
Depression (%) a
MDD, major depressive episode; D, dysthymia.
Sensitivity cannot be calculated exactly, since we did not interview a randomized sample, A direct extrapolation from 13% false-negatives would be incorrect, but the sensitivity was clearly not very high. Discussion
Self-reports have shown that depressive symptoms are even more common among adolescents than in adults (19). Our study confirms the BDI mean scores and the prevalence of scores of a16 from an earlier study bf a Swedish adolescent population (13). American studies have reported the same high symptom frequency (9,10,15), and sometimes even a much higher frequency (14) (Table 5). The gender difference, with a higher prevalence of depression among female subjects, -appears after puberty with the same pattern as that observed in adults (20). Our study, like the earlier Swedish investigation, showed a significant preponderance of depressive symptoms in girls. Such a difference was also found in the Canadian study ( l l ) , but not in most of the studies from the USA (9, 14, 15), in which the boys had high scores close to those of the girls. Validation of the BDI by DICA-R-A and depressive diagnosis during the last year revealed a higher specificity for girls than for boys (75% vs. 65%) Table 5. BDI results in adolescent population studies Participation Study (year) Hammen (1974) Teri (1982) Kaplan (1984) Baron (1986) Larsson (1990) Roberts (1991) Present study
n
%
2272 568 385 291 574 1710 2270
75 87 93 91 61 92
Mean score Age (years) 18-1 9 14-17 11-18 13-17 13-18 15-18 16-17
16
Total
Boys
Girls
-
5.95 7.96 5.16 7.83 4.20 6.49 4.23
6.34 8.80 6.44 12.30 8.50 1.78 7.78
8.5 6.0 10.3 6.3 7.2 6.1
(%I
9.0 32.0 8.6 10.0 13.1 9.7
BDI and adolescent depression and fewer false-negatives for girls (12% vs. 16%). The exact sensitivity could not be calculated, but could not possibly be very high for either sex. The drop-out between screening and interview was lower for girls than for boys (10.3% vs. 15.7%), and so was the dropout in the first screening (6% vs. 10%). Screening a school population for depression by self-rating questionnaire and reaching a correct point prevalence is a difficult task, even with a good instrument such as the BDI. The problems were greater with boys than with girls, due to both higher levels of drop-out and less reliable answers. In the present study, 6.9% of the 2465 adolescents in the population were shown by interview to have fulfilled the criteria for a depressive diagnosis during the last year. If the adolescents who dropped out during the two different stages of the study had not differed from those evaluated, the prevalence during the last year would have been about 8%. We have reason to believe that this figure is not too high, since a large proportion of the drop-out in both screening and interview stages could be attributed to a problematic group of youngsters among whom depression is probably frequent. Boys and girls showed different symptom patterns in depression. The more physical symptoms, such as insomnia, anorexia, fatigue and work impairment, did not differ much between the sexes, but the cognitive content did. Depression in girls was characterized by depreciation of themselves, and in boys it was characterized by depressive mood. These differences might be linked to the way in which boys and girls are brought up and taught the social expectations of their gender. The hormonal changes which occur at puberty increase the frequency of depression and herald the dominance of depression in women (20). It seems less plausible that the sex hormones per se should influence the cognitive content of depression so strongly. The two patterns of depressive symptoms revealed here are consistent with the common social differences between the sexes in western society (21). Young women also tend to ruminate about their depressive feelings more often than young men, a factor which might contribute to more severe and longlasting periods of depression (22). Negative evaluation of self does play a significant role in the development of depression (23), and it delays recovery (24). Thus the tendency for selfdepreciation among girls might be a contributory cause of depression and not only a symptom. Adolescent depression is still not correctly diagnosed often enough. It is essential to describe the symptoms of depression in adolescents, and how they differ from those of adult depression. Knowledge of the differences between the sexes could also aid the search for the correct diagnosis.
Acknowledgements This study was supported by grants from the Swedish Medical Research Council, the Soderstrom-Konigska Foundation, the Thuring Foundation, the Gillberg Foundation, the First of May Flower Annual Campaign and the Sven Jerring Foundation. The authors wish to thank A. Fredriksson, S. Fredriksson, M. von Knorring and C. Jonson for assistance with data collection, H. Anne11for assistance with data analysis, P. Moreno-Hultman for editorial assistance and U. Jonson for secretarial help.
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