Prevalence and short-term stability of depressive symptoms in schoolchildren Larsson B, Melin L. Prevalence and short-term stability of depressive symptoms in schoolchildren. Acta Psychiatr Scand 1992: 85: 17-22. This study examined the prevalence of depressive symptoms in a sample of 471 Swedish schoolchildren aged 8-13 years from urban and rural areas. Children self-reported their experience of depressive symptoms on a Swedish version of the Children’s Depression Inventory (CDI). Short-term stability of children’s depressive symptoms was evaluated for a 6- to 9-week period. In addition, the children’s satisfaction with their school, home and leisure time was assessed. The results indicated that the prevalence of depressive symptoms was related to neither location (urban vs rural) nor age. Although girls experienced significantly more depressive symptoms than boys, the clinical importance of this difference is negligible. Approximately 1% of the schoolchildren reported severe suicidal thoughts. As expected, children’s depression was negatively associated with their home and school satisfaction and leisure interest. A cut-off score of 13 on the CDI could identify the upper 10% of the children in the school sample as depressed and, at the follow-up, 44% of these children continued to be depressed. Overall, the total CDI mean scores obtained in this study were lower than those reported in comparative surveys in Anglo-Saxon countries.
During the 1980s, it has been established that the prevalence of depressive disorders among preadolescent children in a general population is less frequent than (1-5) the prevalence of depressive symptoms (6-21). It is particularly important to include self-report measures in the assessment of childhood depression since such key symptoms as sadness, feelings of loneliness, and suicidal thoughts reflect subjective feelings and self-perceptions of the child. One of the most widely used self-report instruments, the Children’s Depression Inventory (CDI) developed by Kovacs (6), is a downward extension of the Beck Depression Inventory (22). The CDI has been used in several epidemiological studies to evaluate the prevalence of depressive symptoms in children in Anglo-Saxon (6-16) as well as in other countries (21). In a recent cross-cultural investigation of schoolchildren, Ollendick & Yule (14) found no differences in depressive symptoms between children in the United Kingdom and the United States. In addition, the total CDI mean scores were almost identical to those reported by Kovacs (6) for a sample of schoolchildren in Canada. However, somewhat higher CDI norms were found for a school sample of children in Australia in comparison with United States populations (12). While test-retest correlations for school-aged children have been reported to be weak for a l-week
B. Larsson’, L. Melin’
’
Department of Child & Youth Psychiatry, University Hospital, Department of Clinical Psychology, Uppsala, Sweden
Key words: childhood: depression, epidemiology
Bo Larsson, Department of Child & Youth Psychiatry, University Hospital of Uppsala, S-75017 Uppsala, Sweden Accepted for publication July 28, 1991
period (Y = 0.38), stronger relationships have been observed for 3- to 4-week periods ( Y = 0.72-0.77) (16). Furthermore, depressive symptoms in schoolchildren as measured by the CDI have been related to lower self-esteem (6, lo), negative self-concept (15, 16), externalized locus of control (15), hopelessness (5) and anxiety (10, 14, 15). In a recent study of 10- to 15-year-old schoolchildren, Larson et al. (13) also found that depressive symptoms covaried with negative affect and family factors, findings that applied in particular to the older children in the sample. The purpose of this study is to estimate: (1) the prevalence of depressive symptoms in schoolchildren; (2) the short-term stability of these symptoms over a 6- to 9-week period; (3) the association between depressive symptoms and children’s home and school satisfaction and their leisure interests.
Material and methods Subjects
A sample of 471 schoolchildren, 23 1 boys and 240 girls aged 8 to 13 years, was randomly selected from 4 rural and 4 urban schools. Using a 40/60% balance for the distribution of subjects by sex in each class, 9 classes from the urban and 13 from the rural 17
Larsson & Melin
schools were randomly recruited. Children were distributed according to location, sex and age as presented in Table 1. At test 1 only a few inventories, 1.8%, were filled out incompletely and at retest 5.3% of the children did not participate, mainly because of school absence. Assessment
Children in grades 2 to 6 completed the measures during a lesson and were retested after a 6- to 9-week period. For children in second grade classes, each item was read aloud by psychology graduate students, who were also available during the lesson to help and respond to all queries. Testing was anonymous and conducted in group format. The children filled out the CDI, (6), a 27-item self-report questionnaire that includes items regarding cognitive, affective, and behavioral aspects of depression in children. On each item, the child is asked to endorse the one of 3 descriptions that best describes the way he or she has been feeling and thinking during the preceding 2 weeks. Responses are scored on a 0-2 scale with 0 representing the absence of a particular symptom and 2 representing the severe form of a depressive symptom. Thus, the CDI total scores range from 0 to 54. The CDI has proven to have a high internal consistency (5, 6, 9, 11, 14, 16) and a moderate test-retest reliability (from 1 week to 1 year) ( 5 , 6, 11, 16, 17, 20) and to distinguish clinic from non-clinic groups of children ( 5 , 7, 16). A cut-off score of 19 representing the 90th percentile has been suggested by Kovacs (6) and others (1 1, 14) to distinguish nondepressed from depressed children. Further, the total CDI score has been found to be unrelated to type of administration of the inventory, i.e. individual vs group format or numbered vs unnumbered inventories (20). Norma-
Table l . Depressive symptoms in schoolchildren by location, sex and age n
%
Mean
SD
P
Location Urban Rural
209 258
45 55
6.2 6.3
5.8 5.4
NS
Sex Girls Boys
238 229
51 49
6.7 5.8
6.2 4.9
< 0.05
44 80 78 112 104 49
9 17 17 24 22 11
5.4 5.7 6.0 6.9 6.3 7.2
5.4 5.3 5.5 5.5 5.1 7.3
NS
Age (years)
8 9 10 11 12 13
18
tive data for children from Anglo-Saxon countries are also available today (6, 11, 12, 14, 15, 17-20). The short-term stability of depression in the schoolchildren was evaluated by retesting the subjects after a 6- to 9-week period. In addition to completing the CDI, children also rated their satisfaction with their home and school situation, and their leisure interests using the same 0-2 scale as the CDI. Finally, on a 0- to 10-cm visual-analogue scale, children assessed their feelings of sadness during the past 2 weeks. Statistical analysis
Differences between group means for continuous data were analyzed by Student’s t-test or analysis of variance (ANOVA). Relationships between continuous variables were evaluated by Pearson productmoment correlations and between categorical variables by chi-square tests (McNemar test for significance of change over time). T o extract factors in the CDI of clinical interest, a principal components procedure was used followed by a varimax rotation. To delineate those CDI items that best distinguished nondepressed from depressed schoolchildren, a discriminant function analysis was used. Results
Depressive symptoms
Children’s depressive symptoms were first analyzed for location, sex and age effects. Thus, a t-test (Table 1) revealed no difference between children from urban and rural schools on the total CDI mean scores. Therefore, the results of the subsequent analyses are presented for all children collapsed into one group. A further analysis of sex and age effects by twoway ANOVA indicated a significant main effect for sex, F(1, 466) = 4.56, P
During the 1980s, it has been established that the prevalence of depressive disorders among preadolescent children in a general population is less frequent than (1-5) the prevalence of depressive symptoms (6-21). It is particularly important to include self-report measures in the assessment of childhood depression since such key symptoms as sadness, feelings of loneliness, and suicidal thoughts reflect subjective feelings and self-perceptions of the child. One of the most widely used self-report instruments, the Children’s Depression Inventory (CDI) developed by Kovacs (6), is a downward extension of the Beck Depression Inventory (22). The CDI has been used in several epidemiological studies to evaluate the prevalence of depressive symptoms in children in Anglo-Saxon (6-16) as well as in other countries (21). In a recent cross-cultural investigation of schoolchildren, Ollendick & Yule (14) found no differences in depressive symptoms between children in the United Kingdom and the United States. In addition, the total CDI mean scores were almost identical to those reported by Kovacs (6) for a sample of schoolchildren in Canada. However, somewhat higher CDI norms were found for a school sample of children in Australia in comparison with United States populations (12). While test-retest correlations for school-aged children have been reported to be weak for a l-week
B. Larsson’, L. Melin’
’
Department of Child & Youth Psychiatry, University Hospital, Department of Clinical Psychology, Uppsala, Sweden
Key words: childhood: depression, epidemiology
Bo Larsson, Department of Child & Youth Psychiatry, University Hospital of Uppsala, S-75017 Uppsala, Sweden Accepted for publication July 28, 1991
period (Y = 0.38), stronger relationships have been observed for 3- to 4-week periods ( Y = 0.72-0.77) (16). Furthermore, depressive symptoms in schoolchildren as measured by the CDI have been related to lower self-esteem (6, lo), negative self-concept (15, 16), externalized locus of control (15), hopelessness (5) and anxiety (10, 14, 15). In a recent study of 10- to 15-year-old schoolchildren, Larson et al. (13) also found that depressive symptoms covaried with negative affect and family factors, findings that applied in particular to the older children in the sample. The purpose of this study is to estimate: (1) the prevalence of depressive symptoms in schoolchildren; (2) the short-term stability of these symptoms over a 6- to 9-week period; (3) the association between depressive symptoms and children’s home and school satisfaction and their leisure interests.
Material and methods Subjects
A sample of 471 schoolchildren, 23 1 boys and 240 girls aged 8 to 13 years, was randomly selected from 4 rural and 4 urban schools. Using a 40/60% balance for the distribution of subjects by sex in each class, 9 classes from the urban and 13 from the rural 17
Larsson & Melin
schools were randomly recruited. Children were distributed according to location, sex and age as presented in Table 1. At test 1 only a few inventories, 1.8%, were filled out incompletely and at retest 5.3% of the children did not participate, mainly because of school absence. Assessment
Children in grades 2 to 6 completed the measures during a lesson and were retested after a 6- to 9-week period. For children in second grade classes, each item was read aloud by psychology graduate students, who were also available during the lesson to help and respond to all queries. Testing was anonymous and conducted in group format. The children filled out the CDI, (6), a 27-item self-report questionnaire that includes items regarding cognitive, affective, and behavioral aspects of depression in children. On each item, the child is asked to endorse the one of 3 descriptions that best describes the way he or she has been feeling and thinking during the preceding 2 weeks. Responses are scored on a 0-2 scale with 0 representing the absence of a particular symptom and 2 representing the severe form of a depressive symptom. Thus, the CDI total scores range from 0 to 54. The CDI has proven to have a high internal consistency (5, 6, 9, 11, 14, 16) and a moderate test-retest reliability (from 1 week to 1 year) ( 5 , 6, 11, 16, 17, 20) and to distinguish clinic from non-clinic groups of children ( 5 , 7, 16). A cut-off score of 19 representing the 90th percentile has been suggested by Kovacs (6) and others (1 1, 14) to distinguish nondepressed from depressed children. Further, the total CDI score has been found to be unrelated to type of administration of the inventory, i.e. individual vs group format or numbered vs unnumbered inventories (20). Norma-
Table l . Depressive symptoms in schoolchildren by location, sex and age n
%
Mean
SD
P
Location Urban Rural
209 258
45 55
6.2 6.3
5.8 5.4
NS
Sex Girls Boys
238 229
51 49
6.7 5.8
6.2 4.9
< 0.05
44 80 78 112 104 49
9 17 17 24 22 11
5.4 5.7 6.0 6.9 6.3 7.2
5.4 5.3 5.5 5.5 5.1 7.3
NS
Age (years)
8 9 10 11 12 13
18
tive data for children from Anglo-Saxon countries are also available today (6, 11, 12, 14, 15, 17-20). The short-term stability of depression in the schoolchildren was evaluated by retesting the subjects after a 6- to 9-week period. In addition to completing the CDI, children also rated their satisfaction with their home and school situation, and their leisure interests using the same 0-2 scale as the CDI. Finally, on a 0- to 10-cm visual-analogue scale, children assessed their feelings of sadness during the past 2 weeks. Statistical analysis
Differences between group means for continuous data were analyzed by Student’s t-test or analysis of variance (ANOVA). Relationships between continuous variables were evaluated by Pearson productmoment correlations and between categorical variables by chi-square tests (McNemar test for significance of change over time). T o extract factors in the CDI of clinical interest, a principal components procedure was used followed by a varimax rotation. To delineate those CDI items that best distinguished nondepressed from depressed schoolchildren, a discriminant function analysis was used. Results
Depressive symptoms
Children’s depressive symptoms were first analyzed for location, sex and age effects. Thus, a t-test (Table 1) revealed no difference between children from urban and rural schools on the total CDI mean scores. Therefore, the results of the subsequent analyses are presented for all children collapsed into one group. A further analysis of sex and age effects by twoway ANOVA indicated a significant main effect for sex, F(1, 466) = 4.56, P
