**5.3 Results**

146 Epidemiology Insights

of the study were 1) to assess the prevalence of emotional and behavioural problems from different informants in children aged 3-6 years old, and 2) to investigate factors which may be

The study population comprised 474 families and their children attending preschools in the city of Braunschweig (Germany), a moderately sized city with 250,000 inhabitants. Families were recruited for universal and selective prevention efficacy studies of child behaviour problems. Study details for recruitment were described by Hahlweg et al. (2010) and Heinrichs (2006). Data reported here were collected at the first (pre) assessment point. The age of the parents ranged between 23 and 47 years (mothers: *M* = 34.5, *SD* = 5.3; fathers: *M* = 36.4, *SD* = 6.1). The families had between one and four children (*M* = 2.0, *SD* = 0.9). The average age of the target children was 4.5 years (*SD* = 1.0), and 53% (*n* = 253) were boys. Seventy-eight percent (*n* = 219) of the couples were married, and 27 % (*n* = 127) were single parents. 200 fathers (91 % participation rate) completed the questionnaire assessment at pre-test. Forty-two percent of mothers (51 % of fathers) had a higher-track school school leaving qualification (= 13 years of schooling), and 37 % (22 %) had completed medium-track school (= 10 years of schooling). The net family income was equivalent to the German average; 35 % of the families were receiving social security benefits, and 7 % of mothers (5 % of fathers) were immigrants.

To assess psychopathology in children the German translation of the ASEBA Preschool Forms & Profiles (Achenbach & Rescorla, 2000) was used. The CBCL/1½-5 and the C-TRF are similarly constructed to cover an empirical range of behavioural, emotional and social function problems. Both forms comprise 99 items, and the respondent is requested to rate each item, based on the preceding two months, as 0 for *not true*, 1 for *somewhat or sometimes true* or 2 for *very true or often true*. The CBCL/1½-5 was completed by the mothers and

The CBCL/1½-5 consists of three problem scales (Internalizing, Externalizing, and Total Problems) and seven syndrome subscales (Emotionally Reactive, Anxious/Depressed, Somatic Complaints, Withdrawn, Sleep Problems, Attention Problems, and Aggressive Behavior). The C-TRF consists also of three problem scales (Internalizing, Externalizing, and Total Problems) and six syndrome subscales (Emotionally Reactive, Anxious/Depressed, Somatic Complaints, Withdrawn, Attention Problems, and Aggressive Behavior). Studies on the German versions of the ASEBA Preschool Forms have supported the psychometric properties, showing good reliability and validity in both clinical and non-clinical populations (e.g. Plück et al., under review). Since there are no German norms available for the ASEBA Preschool Forms &

Prevalence rates of problem scales and syndrome subscales were calculated for mothers, fathers and caregivers based on the norms provided by Achenbach and Rescorla (2000). Prevalence rates were calculated as a proportion of children with *subclinical* behaviour

fathers, whereas the kindergarten teachers completed the C-TRF.

Profiles, we used the norms provided by Achenbach and Rescorla (2000).

associated with prevalence such as demographic and socio-economic factors.

**5.2 Methods** 

**5.2.1 Participants** 

**5.2.2 Measures** 

**5.2.3 Statistical analysis** 

Table 1 reports the prevalence rates of problem scales and syndrome subscales for different informants. In this sample, the prevalence rate of *Internalizing* problems varied from 7.3 % (fathers) to 12.0 % (mothers) in the borderline range. Across informants, about 12 - 13% of the children met the criterion of the clinical range. For internalizing syndrome scales, 5 - 6 % prevalence rates were obtained for predominantly clinically relevant somatic complaints, anxious depressive behaviour, and withdrawn behaviour. Prevalence rates of *Externalizing* problems ranged from 4.9 % (fathers) to 9.7 % (caregivers) in the borderline range. Across informants, 6 - 9% of the children met the criterion of the clinical range. For externalizing syndrome scales, marginally higher rates of aggressive behaviour (4 - 5% clinically relevant) than attention problems were found. In summary, the results indicate higher prevalence rates on internalizing than externalizing problem behaviour across informants. For *Total Problems*, rates varied from 6.9 % (mothers) to 10.8 % (caregivers) in the borderline range. For the clinical range, 5.8 % (fathers) to 11.0 % (caregivers) of the children met the criterion. Overall, total problems were more frequently indicated by caregivers compared to parents.


Table 1. Prevalence rates in percentage for syndrome scales and *broad-band scales*, and different informants.

For all informants, there were no significant associations between children's age and gender in terms of prevalence of problem and syndrome subscales. Odds ratios ranged between 0.99 and 1.28 and were not significant. Chi-square analysis showed that *Internalizing* problems reported by mothers were overrepresented among mothers with lower education (< 9 years) compared to those with higher education levels (35.1% vs. 26.4 and 16.9%; *χ*2 (2) = 12.31, *p* < .01). Fathers reported significantly more *Total Problems* with lower maternal

The Epidemiology of Child Psychopathology: Basic Principles and Research Data 149

When compared with other studies of older children, many similarities are seen concerning the associations between prevalence and demographic factors. In the current study, parental education, income, and immigrant status were also significantly associated with mental health problems of preschool children. In contrast to earlier studies, we observed effects specific to internalizing problem behaviour. In this context, it is essential to underline the fundamental longitudinal results of Wadsworth and Achenbach (2005), who found more interactions of SES over time, indicating increasing socioeconomic differences for child behaviour problems. The results for odds ratios are consistent with those reported by

The results of the present study revealed that the psychopathology of preschool children was already as high as has been found in studies of school children and adolescents. An increased utilization of child mental health services by older children, who already show disturbance in preschool years, has important implications for early preschool recognition of child mental health problems and indicates the need for the prevention and development of a differentiated delivery of child mental health services for preschool children. Clinicians working in primary care, day care, or school systems need to be attentive to opportunities for early detection and intervention regarding preschoolers' emotional and behavioural problems, particularly since efficacious prevention and treatment exists for the

Within the last century, considerable changes in the health and illness patterns of young children have been observed. One characteristic of this phenomenon, which is referred as the "new morbidity', is the growing importance of mental health concerns (Palfrey et al., 2005). Externalizing problem behaviours are the most common and persistent forms of childhood maladjustment (Campbell, 2006). Kraemer et al. (2000) reported that, at the same time, externalizing behaviours change so much in expression and frequency over the course of development that studies at any single point in development will provide only limited information or misrepresent the phenomenon. Therefore, there is a growing agreement that externalizing behaviour must be studied from a developmental perspective (Costello & Angold, 2006). The present article aims to describe the development of externalizing

Previous studies have investigated the development of externalizing behaviour in the general population (e.g. Bongers et al., 2004; Hofstra et al., 2000; Loeber et al., 2000). However, these studies used two different diagnostic approaches to describe externalizing problem behaviour. The *empirical approach* utilized multivariate statistical techniques to identify sets of problems that tend to occur together. This approach starts with empirical data derived from different informants who describe the behaviour of children and forms the basis of the empirical syndromes of rating scales such as the Child Behavior Checklist (CBCL; Achenbach, 2009) or the Conners' Rating Scales (Conners, 1997). The *diagnostic approach* is to take the diagnostic categories of one of the international nosological systems, the fourth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) or the World Health Organization's International Classification of Diseases (ICD). Instead of disregarding one approach for the other,

Harland et al. (2002) for a larger range of children's age.

psychopathology of young children (e.g. Weisz et al., 2005).

**6. Continuity and change of externalizing behaviour** 

behaviours from preschool age to primary school.

**6.1 Background** 

education compared to higher maternal education (28.3% vs. 6.5 %; *χ*2 (2) = 15.82, *p* < .001). Rates of total problem behaviour were also significantly more common with lower education of fathers (< 9 years) in comparison to fathers with a higher education level (24.7% vs. 8.6 %; *χ*2 (2) = 12.72, *p* < .01). Caregivers reported no significant associations between parents' education and child behaviour problems.

The prevalence of *Internalizing* problems reported by both parents was higher in low-income families (mothers: 35.5 %, fathers: 32.7 %) than in the group with an income of over 3,000 € per month (10.8 % and 9.2 %; *χ*2 (2) = 20.71, *p* < .001; *χ*2 (2) = 12.14, *p* < .01). The prevalence of *Total Problems* reported by mothers is comparable in this context: Children from low-income households (24.3 %) were overrepresented compared to children from higher-income families (3.2 %; *χ*2 (2) = 18.67, *p* < .001). In contrast to these findings, caregivers reported more *Externalizing* problems for children from lower-income families. The results narrowly failed to reach statistical significance.

The immigrant children's adjustment reported by informants was as follows: Non-German children (rated by their mothers) had higher prevalence rates on internalizing problems than those reported for native-German preschool children (48.5 % vs. 20.3 %; *χ*2 (2) = 24.23, *p* < .001). The odds ratio was 3.0 (95 %-CI 1.82-4.96). There were no significant associations between immigrant status, problem behaviour and other informants. There were also no significant discrepancies between parental marital status and prevalence rates of problem scales. The odds ratio for *Internalizing* problems in single-parent families versus dual-parent households was 1.96 (95 %-CI 1.07-2.68). The odds ratio for scoring T ≥ 60 on *Total Problems* was 1.80 (95 %-CI 1.08-3.00) for children with single parent versus dual-parent families.
