Preschool behavior disorders: Their prevalence in relation to determinants

Preschool behavior disorders: Their prevalence in relation to determinants C h a r l e s P. Larson, MD, MSc, I. Barry Pless, MD, FRCP(C), a n d Olli M i e t t i n e n , MD, PhD From the Department of Epidemiology and Biostatistics, McGill University, and the Department of Community Health, Montreal General Hospital, Montreal, Quebec, Canada

The occurrence of behavior disorders was investigated in a prospectively followed 3-year-old birth cohort. Of 1116 eligible children, the parents of 918 were successfully contacted. All a g r e e d to complete a telephone interview and were mailed a Childhood Behavior Checklist (CBCL) standardized for 2- to 3-year-old children; 756 (82%) returned the CBCL. The prevalence of one or more of the deviant behavior Syndromes Identified b y t h e CBCL was 11.1%. From a number of subject characteristics recorded throughout infancy, age-specific determinants for the occurrence of these deviant behaviors were identified. Characteristics most consistently associated with preschool psychopathology included the mother's ill health and lack of social support, the presence of chronic Illness in the child, a n d the frequent use of hospital e m e r g e n c y services. These and other determinant (risk) indicators were entered into logistic regression (LR) models to derived adjusted relative risk estimates for the occurrence of a behavior disorder. The derived LR equations emphasize the important role of both the mother as well and the father and the health of the child. (J PEDIATR1988;113:278-85)

Over the past two decades, several investigators have studied the occurrence of behavior disorders in preschool children, I-9 with widely varying results. The rePorted prevalence has ranged from 10% to 50%. These discrepancies can ~be largely attributed to differences in the definition and identification of behavior disorders in early childhood. Rates identified on the basis of open-ended observations or reporting--for example, temper tantrums--are relatively high, ',~ whereas rates for behaviors defined on the basis of normative behavior distributions3-5or clustering of related symptoms ~~are consistently lower, and generally less than 10% for moderate to severe behavior disorders. Prevalence studies most frequently apply case identifica-

Supported by National Health Research and Development Program (Canada) grant No. 6605-1878-44 and by the Montreal General Hospital-Department of Community Health Physician Association Research Fund. Submitted for publication Dee. 14, 1987; accepted Jan. 29, 1988. Reprint requests: I Barry Pless, MD, Montreal Childrens Hospital, 2300 Tupper St., Montreal, Quebec H3H 1P3, Canada.

278

tion strategies involving the determination of a total behavior rating and a cutoff score that creates normal and abnormal ranges. 11 An alternative is to identify more or less specific behavior disorder entities based on empirically derived clusters of symptoms. 1~12-15This latter approach has not been used often in children less than 4 years of age because of the lack of valid and reliable measures of preschool behavior disorders. Extensive lists of determinant factors that customarily are grouped under biologic and environmental headings have been published. '61~ Unfortunately, the results of CBCL ED HOME SES TBPS

Child Behavior Checklist Emergency department Home Observation for Measurement of the Environment Socioeconomic status Total behavior problem score

determinant investigations are generally inconsistent.19 These inconsistencies are partially explained by differences

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T a b l e I. Early childhood characteristics considered in the analyses Child Gender Neonatal illness Immunization status Feeding problems Chronic illness Injuries Hospitalizations ED visits Child care Mother Age Parity Education Civil status Prenatal courses Health status Smoking behavior Breast feeding Employment Perceptions of Stress Support Health Rewards Early postpartum stage Delivery Type Father's presence Newborn contact Breast feeding

in the definition of abnormality and the assessments of potential determinants derived from retrospective parental recall. The objectives of this investigation were therefore to determine the prevalence of behavior disorders in a 3year-old, prospectively followed birth cohort and to identify, among a wide range of characteristics of early childhood, those significantly related to the occurrence of psychopathologic conditions. These characteristics were then assessed for their predictive utility in clinical or public health settings. METHODS Design overview. The parents of a 1-year birth cohort (1983) were interviewed at 2 weeks and at 6, 12, and 18 months postpartum to document the time course of a wide range of health, environmental, and social factors characterizing the child and family. This cohort was resurveyed during its fourth year (3-year-old children) by the use of telephone interviews and a mailed behavior checklist. Study population. The source population consisted of all

Preschool behavior disorders

279

T a b l e I. Cont'd

Mother-newborn Contact in hospital Sleep or crying problem Mother-newborn Separation Family and social support Father's role Help from friends Social services Number of children Number of younger siblings Demographic and economic Community of residence Ethnicity Immigration status Occupation Yearly family income SES (Green~1) Home observation Home22 Emotional/verbal responsivity Avoidance restriction-punishment Organization of home Play materials Maternal involvement Variety in routine Maternal behavior23 Positive emotional involvement Attitudes toward child Caretaking skill Responsiveness Mother-infant contact Appropriateness

children born in 1983 to women residing within a designated community health district of Montreal. Excluded from admissibility into the study were children with a teenage mother (less than 18 years of age), those whose mother or themselves were hospitalized longer than 10 days postpartum, and those without a parent able to speak French, English, Greek, Portuguese, or Spanish. The source population consisted of 2214 newborn infants, and 2075 of these families were contacted. Of these, 360 denied consent and another 160 were excluded, for an initial enrollment of 1548 infants (75%). After the telephone interview at 18 months, the families were informed that they would be recontacted in the future. Telephone numbers at home, at work, and of a relative were recorded. Cooperation at future contacts was enhanced by birthday cards mailed at ages 2 and 3 years. Over a 3-week period in ktte 1986, an effort was made to contact all families who had completed the 18-month interview and all those who had last completed an interview at 12 months and had not formally exited from the

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Table II. Prevalence of particular bahavior disorders, aggregate prevalence for any one or more, and the proportion also having an abnormal total behavior problem score Prevalence Disorder

Emotional Depression Withdrawal Sleep problem Somatic problem Conduct Aggressive Destructive Any one or more

%

No.

% With a b n o r m a l TBPS

1.3 1.2 3.2 4.0

10 9 34 44

70 89 50 55

0.8 1.4 11.1

6 11 83

100 100 55

study. Of the 1116 families thus targeted, 918 (82%) were contacted. All agreed to complete a telephone interview and a mailed questionnaire. Those interviewed during the fourth postpartum year relative to those interviewed at entry tended to be somewhat more established in terms of education, income, and marriage; however, statistically significant differences (p <0.05) were limited tO family income. Outcome assessment. Parents received by mail, and were asked to complete, the Child Behavior Checklist for 2- to 3-year-old children.2~ Within 2 weeks after the mailing, parents were telephoned to confirm receipt of the questionnaire and to encourage its completion. CBCLs were accepted up to 6 weeks after the final mailing, at which point 756 questionnaires (82%) had been returned and properly completed. The questionnaire contains 99 behavior items, scored 0 (not true), 1 (somewhat true), or 2 (very or often true), according to how well the parent judges the items to describe their child. This wide range of behaviors has been empirically grouped according to symptom clusters found in children with varied psychopathologic conditions. This allows for the identification of six deviant behavior syndromes: depression, withdrawal, sleep problems, somatic problems, aggressiveness, and destructive behavior. Based on application among "normal" children, a T score of 70 (>90th percentile) defines deviance for any of the six syndromes. In addition, raw scores are summed to create a total behavior problem score, with the upper 10% of scores in the study population defined as abnormal. Determinant data. Demographic, health, social, and behavioral characteristics were recorded at each follow-up survey throughout infancy. Included were social and demographic data, obstetric and perinatal histories obtained at 2

weeks postpartum, and a health and social status inventory completed at 6, 12, and 18 months postpartum. Estimation of socioeconomic status was based on the mother's education and the occupation of the head of household (GreenEl). For families on welfare, a minimum score of 21 was assigned. A 50% random sample of families were also visited at home at 6 weeks and at 6, 12, and 18 months postpartum. During these visits the Home Observation for Measurement of the Environment22 and the Maternal Behavior Scale 23 were completed. The former provides information about the physical and social environment of the child at home; the latter more specifically focuses on the mother's caretaking skills and interaction with her child. The potential determinants were grouped under the six headings listed in Table I. Analysis. The prevalence of each deviant behavior syndrome and the aggregate prevalence of one or more deviant behaviors were calculated. Because of small absolute numbers, the withdrawal and depression syndromes were combined to form an "emotional disorder" category, and the aggressive and destructive syndromes were combined to form a "conduct disorder" category. Chi-square or t test statistics were calculated for bivariate associations between earlier childhood characteristics and the resultant four deviant behavior categories: emotional disorder, sleep problem, somatic problem, and conduct disorder. Statistically significant associations (p_ <0.05) were adjusted for confounding by SES, mother's education, and other extraneous determinants)4 Logistic regression models were fitted to relate the occurrence of each of the four deviant behavior categories and abnormal TBPS to the set of its identified determinants.25 From the logistic regression models, adjusted relative risk estimates, including confidence intervals, were calculated. 26 RESULTS The prevalence of each deviant behavior syndrome, whether occurring alone or in combination with others, and the aggregate prevalence f6r one or more deviant behaviors are summarized in Table II. The aggregate prevalence was found to be 11.1%. Also shown in this table is tLe proportion of children found to have any given deviant behavior syndrome who also had an abnormal TBPS. A high proportion of children with a conduct disorder (15 of 19) or with an emotional disorder (17 of 17) had an abnormal TBPS. Nonetheless, when one includes sleep and somatic problems, only just over half of the children with any particular deviant behavior syndrome would have been identified as abnormal on the basis of the TBPS alone. The mean TBPS score was 32.9 (SD = 18.8), and a total score

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2 81

Table III. S u m m a r y table of d e t e r m i n a n t s significantly (p <0.05) associated with each b e h a v i o r outcome Outcomes Determinant factor Relatively general determinants Mother's ill health Minimal caretaking role, father Frequent ED visits Lack of perceived support, mother Determinants with specific effect Neonatal Mother's postpartum health Home, 6 wkT Maternal behavior score, 6 wkJ" Lack of help at 2 wk Father at delivery Parental competence Maternal behavior score, infancy* Incomplete immunizations Positive injury history Maternal smoking Other maternal descriptors Breast-feeding history1" Increased perceived stress, mother Decreased perceived rewards, mother Decreased perceived health, mother Primiparity Multiparity Other child descriptors Chronic illness in child Home, infancyJ" Alternative child care Demographic factors Mother's education Family income SES

Emotional Disorder

Sleep problem

Somatic problem

Conduct disorder

Any behavior*

Abnormal TBP$

x

x x

x x

x x

X

X

X

X

x x

x

x x

X

X

x

X

X

x

x

X

X

x x

x x

X

X

x x

X

x x

X

x

X

X

x

X

X

X

X

X

X

x x

x

x

x x

x

x x x x x

x x

X

X

x

X

X

X

X

*One or more deviant behaviors. ~'Negative association.

of 56 or greater represented the upper 10% r a n g e of scores. Characteristics t h a t were significantly (p < 0 . 0 5 ) associated with the specific disorders identified, a n a b n o r m a l T B P S , or t h e aggregate entity of any one or m o r e deviant behaviors are s u m m a r i z e d in T a b l e I l l . Characteristics are grouped according to w h e t h e r they were significantly associated with the behavior outcomes in a relatively

general m a n n e r or were relatively specific. Those found to be specific are further subgrouped according to what or w h o m they are descriptive of. All five "neonal~al" characteristics were significantly associated with the occurrence of an emotional disorder. Similarly, t h e four factors reflecting on p a r e n t a l c o m p e t e n c e were all associated wtih the occurrence of somatic problems. T h e f i n a l fitted logistic regression models relating t h e

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T a b l e IV. Logistic regression analyses of each behavior disorder in relation to its determinants: point estimates, s t a n d a r d errors (SE) and their associated p values, a n d relative risk estimates Model Emotional disorder intercept ED visits, 12-18 mo None* One or two Three or more Mother: help from others by 2 wk Yes* None Sleep problems intercept Parity Multiparous* Primiparous Father's role, 12 mo Shared to equal* None to minimal ED visits, 12-18 mo None* One or two Three or more Somatic problem intercept ED visits, 12-18 mo None* One or two Three or more Father at delivery No* Yes Injury by 18 mo No* Yes Conduct disorder intercept Mother's smoking if 25 cigarettes/day Chronic illness, 12 mo No* Yes Mother: emotional problem, 18 mo No* Yes Father's role, 12 mo Shared to equal* None to minimal

Point estimate

$E

-2.72

0.65

p value

Relative rlsk (95% Cl)

0.004 -0.59 -2.38

0.57 0.69

10.8 (5.4-21.5) 0.04

-1.89 -2.18

0.64 0.66

6.6 (3.5-12.5) 0.002

-2.14

0.66

8.5 (4.4-16.4) 0.008

-1.38

0.50

4.0 (2.4-6.5) 0.064

-0.05 -1.80 -5.16

0.49 0.76 1.03

6.1 (2.8-13.0) 0.019

-0.59 -1.63

0.38 0.57

5.1 (2.9-9.0) 0.048

-2.14

1.02

8.5 ~3.1-23.7) 0.086

-0.67 -4.04 -0.07

0.37 0.70 0.02

2.0 (1.4-2.8) 0.005

6.2 (3.2-11.9)

0.006 -2.17

0.76

8.8 (4.1-19.1) 0.006

-1.82

0.66

6.2 (3.2-12.0) 0.009

-1.89

0.72

6.6 (3.2-13.5)

cI, Confidence interval. *Reference category for relative risk calculations.

occurrence of each behavior disorder to various determin a n t factors are given in T a b l e IV. Only d e t e r m i n a n t characteristics fitted into each model at a p value <0.10 are presented. T h e adjusted relative risks estimate a child's risk for a particular deviant behavior between the presence

a n d absence of a particular d e t e r m i n a n t realization, conditional on all other d e t e r m i n a n t s in the model. T h e confidence intervals provide the r a n g e of values within which the true relative risk will fall 95% of the time. L a r g e increases in relative risk for a b e h a v i o r disorder were

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consistently found among children frequently visiting an emergency department, among children whose father had a minimal caretaking role, and among children whose mother lacked social support or reported emotional problems. DISCUSSION The object of investigation in this study was the occurrence of preschool behavior disorders. The CBCL was chosen as the basis of outcome classification because of its suitability for survey used and its orientation to particular deviant behavior syndromes in addition to a total abnormal behavior score. E~The empirically derived deviant behaviors are not to be regarded as equivalent to psychiatric diagnoses. However, in comparison to diagnoses, these deviant behaviors provide relatively more reliable ratings of psychopathologic conditions among children in the age group studied.Z~ 27-31 The aggregate prevalence of one or more deviant behaviors in this cohort of 3-year-old children was 1 1.1%. This rate is higher than those reported from previous investigations of moderate to severe behavior disorders among preschoolers, 35 but it is consistent with reported rates for school-aged children? 2 In this study, only about half of those with a specific deviant behavior would have been identified as abnormal on the basis of a TBPS in the upper 10%. This finding indicates that investigations identifying abnormality on the basis of an abnormal total score may miss a significant proportion of children with specific disorders (i.e., those who do not manifest a wide range of deviant behaviors). Conversely, one difficulty with the identification of specific deviant behaviors is that the rates for each are inevitably low. In this investigation, specific rates of prevalence varied between 0.8% for aggression and 4.0% for somatic problems. With such low rates, instability of the prevalence estimates will occur and is manifest in their relatively wide corresponding confidence intervals. How valid are the rate estimates from this investigation? Within the cohort, the prevalence estimates are probably conservative. Despite a 37% dropout between birth and the fourth-year follow-up, the study base is similar to the cohort at entry. They differ in a somewhat higher educational or income status among the children retained; therefore the SES was higher overall. However, higher occurrence rates have not consistently been found in lower SES preschool populations? ,4,17 In the search for determinants of childhood behavior disorders, other investigators have commented on the problems that occur with nonspecific measures, from which only general predispositions or vulnerabilities can be

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283

identified?3; 34 In this investigation, the search for determinants of the four specific categories of disorder resulted in the identification of several characteristics associated in a relatively general manner with all four deviant behavior syndromes, the TBPS, and the aggregate occurrence of a disorder. In other instances, relatively specific associations between determinant characteristics and a particular outcome Were identified. Determinant characteristics significantly associated with most or all the behavior outcomes included ill health in the mother, father's lack of help with caretaking, and frequent use of hospital emergency department services. The association of psychopathologic disorder with the mother's health has been reported in several previous investigations?, 7,13,35 However, other studies that have prospectively followed up children of mentally disordered parents have not Consistently found increased rates of behavior disorder) 6-38 The role of frequent ED use as a determinant may reflect parental insecurity or lack of support. During the fourth-year follow-up interview, mothers were asked about their perceived level of support from others relative to support received before the birth of the child. Less support was associated with three of the four deviant behavior syndromes. Lack of social support has been associated consistently with the occurrence of preschool deviance. 3,4,6,39,4~No evidence of an association between ED visits and acute or chronic illness in the child was found, so the child's health alone does not explain such frequent use.

Several differences in determinants among the behavior disorder outcomes were apparent. The absolute number of children with a particular deviant behavior was small, and this limits the power to detect weaker associations. Nonetheless, the associations identified lend further support to the influence of early childhood experiences on the differential development of preschool psychopathologic conditions. ,Emotional disorders" were associated with all five descriptors of the neonatal period, including measures of the home environment and maternal behavior ratings at 6 weeks postpartum. Many of these early characteristics are descriptive of the mother and her early patterns of interaction with the child. Emotional disorders were also associated with perceived lack of support, with ill health in the mother, and with minimal or no help from the father in caretaking. It appears therefore, that the occurrence of emotional disorders in these children is influenced by several neonatal experiences that reflect maternal caretaking and social support. The occurrence of "conduct disorders" was similarly associated with several neonatal characteristics but also

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with later negative maternal perceptions of stress, support, and personal reward. However, these maternal perceptions may be the result of the child's behavior, rather than related to its cause. Several characteristics indicative of parental competence were included in the analyses4~: incomplete immunization, maternal smoking, lower maternal behavior scores during infancy, and higher injury rates. The occurrence of "somatic problems" was uniquely associated with each of these factors. It has been suggested that there may be a reporting bias resulting in ostensibly more somatic complaints among low SES populations, but somatic problems were not more common among the lower SES families in this cohort. Reported sleep problems were especially frequent among firstborn children of mothers with high levels of perceived stress. The lack of experience and insecurity frequently present in new parents may lead them to give greater attention to their child's sleep patterns and therefore may lead to relative overreporting of sleep problems. Demographic characteristics such as SES, family income, and maternal education were not associated with any particular behavior disorder. They were, however, associated with the more g l o b a l TBPS and aggregate prevalence outcomes. This latter finding suggests that with larger numbers of subjects within the particular behavior disorder entities, significant associations may have been found. The potential association of demographic characteristics with preschool behavior disorder has been frequently studied, with inconsistent results. 8,42-44 With the exception of the father's presence at delivery, none of the early postpartum experiences were significantly associated with the subsequent occurrence of a behavior disorder. There is no obvious explanation for the strong negative association of the father's presence with emotional and somatic disorders. Hence, this factor should be considered in future analyses for confirmation of the unexpectedly strong association with withdrawal-depression and somatic disorders. The logistic regression analyses were conducted with a view to the prediction of particular psychopathologic profiles. The value of these analyses is in their potential for quantitative risk asseSsment of children or their families on the basis of combinations of specific characteristics, and the subsequent targeting of families for prevention. For each of the behavior disorders identified, the fitted logistic regression models retain characteristics as apparent determinants of their occurrence. One characteristic repeatedly retained in the equations was frequent ED use. This lends support to the idea of targeting frequent users, but only if an effective intervention can be provided.

The Journal of Pediatrics August 1988

The applicability of these results to the prediction of deviance within general preschool-aged populations is limited by two important factors. First, the prevalence rates for individual disorders is low, and therefore even a 10-fold excess risk will be relatively small in absolute terms. Second, the standard errors around each estimate result in unacceptable levels of accuracy. If, in fact, one of ten 3-year-old children has a behavior problem, one must then ask, what are the long-term implications? Further follow-up is needed to Confirm whether these behaviors persist and, if so, what impact they have on the child, family, and community. Achenbach et al 2~reported that 1-year stabilitY is greatest for aggres: sive and destructive syndromes (r = 0.71 and 0.72) and lowest for depression ( r - - 0 . 5 6 ) . This is consistent with other follow-up studies of childhood psychopathologic conditions, which also report high Stability for aggressive or conduct disorders) ~,45-4sOn the other hand, emotional problems such as withdrawal or depression often remit spontaneously.46.48 This investigation, from its inception, proceeded under the premise that early psychosocial experiences are important determinants of mental health. The results indicate that different conclusions can be drawn from analyses of particular deviant behaviors versus holistic measures of behavior disorder, with the former providing useful insights into the varied etiologic contributions of early childhood experiences. REFERENCES

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