From the University of Hertfordshire, Department of Psychology, Wolke Research Group, Hatfield Campus, Hatfield/Herts, United Kingdom
| ABSTRACT |
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Methods. Sixty-four infants who were referred for persistent crying in infancy (PC; mean age: 3.8 ± 1.3 months) were reassessed at 8 to 10 years of age and compared with 64 classroom controls (CC). The major outcome measure was pervasive hyperactivity or conduct problems defined as parent, child, and teacher ratings that across informants were within the borderline/clinical range according to the Strengths and Difficulties Questionnaire (SDQ). Ratings of other behavior problems, parent ratings of temperament, and teacher assessment of academic achievement were also obtained.
Results. Ten (18.9%) of 53 PC had pervasive hyperactivity problems (child, parent, and teacher reported) compared with 1 (18.9%) of 62 CC (odds ratio: 14.19 [1.75114.96]). Parents (29 [45.3%] of 64 vs 11 [17.2%] of 64; 4.00 [1.779.01]) and children (30 [46.9%] of 64 vs 17 [26.6%] of 64; 2.44 [1.165.12]) but not the teachers reported more conduct problems. Parents of PC rated the temperament of their children to be more negative in emotionality (PC mean: 3.0 ± 1.0; CC: 2.4 ± 1.0; effect size: 0.6) and difficult-demanding (PC mean: 5.2 ± 1.3; CC: 6.3 ± 0.9; effect size: 1.0). Academic achievement was reported by teachers to be significantly lower for PC than CC, in particular for those children with pervasive hyperactivity problems.
Conclusions. Infants who are referred for PC problems and associated sleeping or feeding problems are at increased risk for hyperactivity problems and academic difficulties in childhood.
Key Words: persistent crying colic hyperactivity conduct disorder academic achievement temperament
Abbreviations: PC, persistent crying CC, classroom control subjects D, dropout NS, not significant df, degrees of freedom CA, Cronbachs
SDQ, Strengths and Difficulties Questionnaire TAAS, Total Academic Achievement Score ES, effect size
| INTRODUCTION |
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Others have speculated that not unexplained crying per se but persistent problems with behavioral control, such as the inability to stop crying and to regulate sleeping or feeding behavior in infancy, are precursors of behavior control difficulties such as hyperactivity or conduct problems in childhood.18,2123 This study prospectively investigated a group of infants who persistently cried in the first 6 months of life and compared them for pervasive hyperactivity and conduct problems and other behavioral and academic difficulties with classrooms control subjects (CC) at the age of 8 to 10 years.
| METHODS |
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2 (degrees of freedom [df]: 1) = 0.83; P = .514, NS). Furthermore, D and PC were compared on 18 sociodemographic factors (birth weight, marital status, family income, housing, employment, etc), 12 feeding variables, 3 sleeping variables, 12 health problem items, total health problems, and infant weight at baseline.25 No differences were found for all but the following variables: dropouts had mothers who were in paid employment more often (9 [24.3%] of 37 vs 2 [3.1%] of 64;
2 (df: 1) = 10.86; P < .001), and the infants were more often in regular day care (6 [16.2%] of 37 vs 3 [4.7%] of 64;
2 (df: 1) = 3.84; P < .05) at baseline. Of the 64 infants who were referred for PC, 5 (7.8%) of 64 had only a PC problem; 10 (15.7%) of 64 also had sleeping problems; 20 (31.2%) of 64 had additional feeding problems; and 29 (45.3%) of 64 had crying, sleeping, and feeding problems.
Twenty-four of the participating children (24 [37.5%] of 64) were referred before 12 weeks of age; 8 of 24 did not qualify anymore as persistent criers according to modified Wessel criteria at the follow-up 3 months later (baseline age: 73 ± 10 days; baseline fuss/cry: 4 hours 41 minutes ± 1 hour 7 minutes; follow-up: 2 hours 9 minutes ± 1 hour 14 minutes), whereas 16 of 24 remained persistent criers 3 months later (baseline age: 66 ± 13 days; baseline: 6 hours 21 minutes ± 1 hour 37 minutes; follow-up: 4 hours 33 minutes ± 1 hour 18 minutes). Forty (62.5%) of 64 were referrals after the age of 12 weeks (baseline age: 136 ± 27 days; baseline: 5 hours 26 minutes ± 1 hour 26 minutes; follow-up: 3 hours 13 minutes ± 1 hour 48 minutes). Of the 40 infants who were referred after 12 weeks, 19 were still persistent criers in the follow-up 3 months later (ie, >6 months of age). Thus, all but 8 infants were persistent criers after the age of 3 months.
Of the 64 PC, 31 had been assigned to a no-treatment control condition (received normal primary care) in infancy and 33 had received telephone contact with a parent volunteer from the self-help group CRY-SIS who herself had previously had an infant who persistently cried.24 Fifteen of 33 shared their feelings and coping strategies with the mother (empathy condition), and 18 of 33 were provided with behavioral management advice. The follow-up findings of the original trial indicated that infants reduced crying significantly more in the behavioral management than in the empathy or control condition.24 However, fuss/cry amounts at 3 months follow-up were still substantially higher than expected in infants at this age in all 3 subgroups.24
The parents who had consented to participation in the follow-up study were asked to consent for the investigators to approach their childrens teacher when the children were 8 to 10 years of age (9.7 ± 0.6 years). The teachers were asked to select 2 children of the same gender in the class closest in age to the target child. Inclusion criteria for CC were same gender and that they had, according to retrospective parental reports, not cried >3 hours per day on 3 days per week during any week in the first 6 months of life. Four CC were excluded because of PC in infancy. When both control parents agreed to participation and were suitable, 1 was randomly selected to obtain a same size control sample (n = 64). Parents and children were sent a set of standard questionnaires for completion (the child questionnaire was in a separate envelope). When applicable, the reliability coefficients for scales (Cronbachs
[CA]26) as determined for the total sample (N = 128) and the 64 PC and 64 CC separately are shown in brackets. The parent questionnaire included detailed questions about sociodemographic characteristics and current health,25 including 6 items on eating behavior (eg, eating too little, too much) and 7 items on current sleeping difficulties (eg, problems with falling asleep). Two questionnaires of child temperament, the Emotionality, Activity, Sociability Temperament Survey27 with the subscales shyness (total sample CA: 0.73; PC: 0.73; CC: 0.65), emotionality (0.87; 0.87; 0.84), activity (0.78; 0.80; 0.76), and sociability (0.58; 0.60; 0.57) and the Childhood Temperament Impression Scale (adapted from Wolke et al24) were also included. Principal components analysis with varimax rotation28 of the 13 Childhood Temperament Impression Scale items rated on 9-cm visual analog scales (eg, mood: very bad tempered/irritable to very happy/cheerful) yielded 2 factors: Difficult-Demanding (items: mood, demanding, difficult, unhappy about childs temperament, stressful; total sample CA: 0.92; PC: 0.92; CC: 0.89) and Adaptability (wariness, adaptability 0.64; 0.62; 0.69). The parents were also asked to complete the Strengths and Difficulties Questionnaire (SDQ29), which consists of 5 subscales: Hyperactivity (CA: 0.79; PC: 0.81; CC: 0.69), Conduct problems (0.67; 0.53; 0.71), Emotional problems (0.81; 0.83; 0.81), Peer problems (0.73; 0.74; 071), and Prosocial behavior (0.76; 0.72; 0.78). A total score based on the first 4 subscales and scale scores for each subscale separately were computed. The SDQ has been shown to be a reliable and valid screening for identifying children who meet Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria and require psychiatric treatment.30,31 A child32 and teacher29 version of the SDQ was also completed by the child and teacher, respectively. The internal consistency coefficients were comparable to those reported for the parents. Furthermore, the total score and each subscale score were dichotomized into normal versus borderline/clinical (score >80th percentile according to Goodman29,33 [replicated by Wolke et al33 for <11-year-olds]). Teachers were also asked to rate the scholastic performance of the child compared with expected standards in the 11 national curriculum subjects English, math, science, technology, geography, history, information technology, art, music, physical education, and religion on 5-point rating scales (1, very below average; 3, average; 5, very above average). Principal components analysis with varimax rotation indicated that the first 7 subjects (English, math, science, technology, geography, history, and information technology) loaded on 1 factor and were combined to give a Total Academic Achievement Score (TAAS; CA: 0.92; PC: 0.91; CC: 0.92). Furthermore, mothers completed the Edinburgh Postnatal Depression Scale34 when their children were 8 to 10 years of age.
Fully completed child and parent questionnaires were available for all PC and CC (N = 128); however, teacher reports for 11 PC and 2 CC were not obtained as parents did not provide consent for completion of teacher ratings. Ethical permission for the study was provided by the University of Hertfordshire Ethical Committee in accordance with the guidelines of the Helsinki Declaration, revised 1983.
Statistics
Comparisons between PC and CC were conducted using independent sample t test for interval-scaled dependent variables. Effect size (ES) for mean comparisons was computed as Cohens d35 (ie, expressed as standard deviation unit differences using g-power software).36 Comparisons on categorical dependent variables were cross-tabulated, and crude odds ratio with 95% confidence interval were determined by logistic regression within SPSS version 10. T tests, odds ratios, and 95% confidence intervals with
2 statistics are presented with corresponding 2-sided P values (P < .05, < .01, or < .001). Post hoc analyses of mean differences in hyperactivity and conduct scale scores between treatment groups (behavior management, empathy, no-treatment control subjects) were conducted using 1 factorial analysis of variance.
| RESULTS |
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2 (df: 1) = 0.05; P = .50, NS).
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2 (df: 1) = 9.89; P < .01), the parents (25 [39.1%] of 64 vs 8 [12.5%] of 64; 4.49 [1.8310.98];
2 (df: 1) = 11.80; P < .001), and the teachers (13 [24.5%] of 53 vs 5 [8.1%] of 62; 3.71 [1.2211.22];
2 (df: 1) = 5.87; P < .05; Fig 1). Ten of 53 PC (18.9%) had pervasive hyperactivity problems in the borderline/clinical range (child, parent, and teacher reported) compared with 1 of 62 of the CC (1.6%; odds ratio: 14.19 [1.75114.96];
2 (df: 1) = 9.84; P < .01). When the stricter criterion of pervasive hyperactivity scores >90th percentile was applied, it just failed to be significantly different between groups (5 [9.4%] of 53 vs 1 [1.6%] of 62; 7.8 [0.9066.9];
2 (df: 1) = 3.54; P < .07). Parents (29 [45.3%] of 64 vs 11 [17.2%] of 64; 4.00 [1.779.01];
2 (df: 1) = 11.78; P < .001) and children (21 [32.8%] of 64 vs 5 [7.8%] of 64; 2.44 [1.165.12];
2 (df: 1) = 12.36; P < .001) also reported more conduct problems in the borderline/clinical range (Fig 2).
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No differences in Hyperactivity or Conduct scores were found according to treatment in infancy (Hyperactivity: Behavioral management [M = 4.7 ± 3.2], Empathy [M = 4.7 ± 3.8], no-treatment control subjects [M = 4.7 ± 2.7], F2,61 = 0.10; P = .91, NS; Conduct problems: Behavioral management [M = 2.2 ± 1.7], Empathy [M = 2.5 ± 2.5], no-treatment controls [M = 2.4 ± 1.7], F2,61 = 0.11; P = .89, NS).
In the secondary outcome measure TAAS (N = 112), 2 CC had a geography rating missing (CC n = 60) and 1 PC had a technology rating missing (PC n = 52); the PC scored lower, on average, than CC (PC grand mean: 3.1 ± .8; CC grand mean: 3.4 ±.6; t (110) = -2.41; P < .05; ES: 0.4). Comparisons on the individual items of the TAAS showed that persistent criers in infancy scored lower in science (PC mean: 3.2 ± 0.9; CC mean: 3.6 ± 0.7; t (113) = -2.63; P < .01; ES: 0.5), English (PC mean: 3.1 ± 1.1; CC mean: 3.5 ± .8; t (113) = -2.08; P < .05; ES: 0.4), geography (PC mean: 3.1 ± .8; CC mean: 3.4 ± 0.7; t (111) = - 2.27; P < .05; ES: 0.4), and history (PC mean: 3.1 ± 0.8; CC mean: 3.4 ± 0.6; t (113) = -2.04; P < .05; ES: 0.4).
Higher SDQ Hyperactivity and Total Deviance scores of child, parent, and teacher ratings were consistently correlated with lower TAAS scores (Table 3). Furthermore, child and parent ratings of emotional problems, child ratings of peer problems, and teacher ratings of conduct problems were significantly correlated with lower academic achievement (Table 3). The PC with pervasive hyperactivity (10 of 52; 1 TAAS score missing) had much lower academic achievement scores (TAAS means: 2.5 ± 0.8) than the CC (n = 60; 3.4 ± 0.6; t (68) = 4.58; P < .001: ES: 1.1) or PC without pervasive hyperactivity (n = 42; 3.3 ± 0.7; t (50) = 3.16; P < .01; ES: 1.1).
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2 (df: 1) = 5.93; P < .05) or eating wrong foods more frequently (PC: 15 [23.4%] of 64; CC: 6 [9.4%] of 64; 3.0 [1.078.20];
2 (df: 1) = 4.61; P < .05). | DISCUSSION |
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Significant associations of difficult temperament in the second or third year of life with externalizing and hyperactivity problems have been reported previously.23,37,38 These findings suggest that pervasive problems of behavior regulation (hyperactivity) and poorer academic achievement are related to problems of controlling behavioral states (eg, crying) detectable already in the first 6 months of life. This is in contrast to previous reports that found only small effects of prolonged crying in early infancy on behavior in the toddler and preschool years.5,8,10,18,39 The differences in findings may be accounted for by differences in the populations studied. First, the infants with prolonged unexplained crying in previous studies were identified when they were well below 3 months of age at a time when cry amounts generally show an increase and mostly reduce spontaneously by 3 months (ie, colic crying40). In this study, all but 8 of the children were still fussing and crying >3 hours a day after 3 months of age when the expected average fuss/cry amount is <1 hour 15 minutes a day in UK infants of comparable age.3 A comparison of the 8 infants who ceased PC after 3 months to the rest with infants in the PC group was not meaningful because of a lack of statistical power. Second, none of the previous longitudinal studies reported on co-associations of PC with sleeping or feeding problems. This self-referred sample showed a high co-association with sleeping and feeding problems that has also been reported for other self-referred samples.41,42 Only 5 infants had just a PC problem, and statistical comparison of these 5 with the 59 infants with multiple behavior problems lacked power. The prevalence of infants with multiple behavior difficulties in infancy is unknown. According to a community study of 5-month-olds, it may be approximately 2% in the infant population.18 Third, although behavioral management did lead to more reduction in fussing/crying in infancy compared with no or empathy intervention, all infants in this study still cried more than normative infants of 4 to 7 months of age.24 There were no differences on behavioral outcome in childhood according to treatment in infancy. The sample thus consisted of infants with highly persistent crying and mostly multiple behavior problems in infancy. The reduced variation in extreme groups may explain that the amount of fussing/crying at baseline did not correlate significantly with Hyperactivity or Conduct scores at 10 years.
The pattern of previous findings and results here leads us to speculate that although colic that resolves by 3 months (ie, is transient) has no or few long-term adverse effects,6,811,13,14 those infants with PC and multiple behavior difficulties are at increased risk for externalizing and hyperactivity problems. This is consistent with findings from another recent study of infants who were referred in the first 6 months and had a history of several months of unexplained crying.42 According to parent reports at 30 months, behavior problems were much more frequent in these infants than expected according to the scales norms. However, in the previous study, maternal bias in reporting on behavior could not be excluded. In contrast, our follow-up extends into middle childhood and used several informants, including teachers. Unfortunately, subgroup analysis in our study to test whether single versus multiple infant problems or the persistence of crying problems beyond 3 months of age are more strongly associated with hyperactivity was not possible because of sample size restrictions. Furthermore, although this study used multiple informants to define pervasive hyperactivity problems with a valid screening instrument,2931 more detailed clinical and neurobehavioral assessment would have been desirable for a firm diagnosis of attention-deficit/hyperactivity disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition or hyperkinetic syndrome according to the International Classification of Diseases, 10th Revision.
Alternative pathways may explain the association between infant difficulties in behavior regulation and childhood hyperactivity and warrant future exploration. The heritability of hyperactivity is moderate to high43,44 and has recently been linked to specific genes.45 We may speculate that the individual characteristics of state regulation are stable over time as a result of genetic liability44 or, alternatively, because of underlying neurodevelopmental problems that were not detected in routine examination.46,47 For example, a higher rate of PC as well as more hyperactivity-attention problems have been reported in neurologic at-risk groups such as very low birth weight children.48,49 The neurobiological underpinnings for poorer state regulation may be sought in the biological targets of stimulants, the dopaminergic and noradrenergic system. Alternatively, the early problems with PC and state regulation are challenging to parents. They form negative views5,6,16 that maintain parenting difficulties and the problems that these infants have in state and behavior regulation.50 Thus, the behavior outcome may be a result of a self-fulfilling prophecy related to the earlier labeling.
Whatever the reasons, health professionals should be aware that those with PC problems that last more than several months in infancy and often associated feeding or sleeping difficulties seem to be at increased risk for hyperactivity problems in childhood. Identification of infants and families that are slow to recover from colic and the development of appropriate interventions for these families remain important clinical challenges.22,41,51
| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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Reprint requests to (D.W.) University of Hertfordshire, Department of Psychology, Wolke Research Group, Hatfield Campus, College Lane, Hatfield/Herts AL10 9AB United Kingdom. E-mail: d.f.h.wolke{at}herts.ac.uk
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