Cognitive and educational outcomes of maltreated and non-maltreated youth: A birth cohort study

Abstract

Objectives:

Previous research suggests that child maltreatment is associated with adverse outcomes, but the potential impact on cognitive and educational outcomes into adulthood has rarely been studied using a birth cohort design. The aim of this study is to investigate whether child maltreatment is associated with adverse outcomes in cognitive function, high school completion and employment by the age of 21.

Methods:

Longitudinal birth cohort study commencing in the prenatal period, with mothers and infants followed up to age 21. Of the original birth cohort of 7223, 3778 (52.3%) young people participated at age 21. Child maltreatment was identified by linkage with prospectively collected data from the relevant government agency. Associations between child maltreatment (abuse and neglect) and the outcomes were adjusted for relevant sociodemographic and perinatal variables.

Results:

After full adjustment, young people who had been notified as cases of child maltreatment had reduced performance on the Peabody Picture Vocabulary Test by over a quarter of a standard deviation (coefficient = −2.85, p = 0.004). Maltreated young people also had three times the odds of failing to complete high school (odds ratio = 3.12, p < 0.001) and more than twice the odds of not being engaged in either study or employment at age 21 (odds ratio = 2.38, p < 0.001). Both abuse and neglect were similarly associated with adverse outcomes.

Conclusion:

Child maltreatment, including both abuse and neglect, is associated with adverse cognitive, educational and employment outcomes in young adulthood. This adds further impetus to efforts to prevent child maltreatment and assist young people who have experienced it.

Keywords

Cognitive testing educational attainment longitudinal study child abuse child neglect

Introduction

Child maltreatment – including both abuse (physical abuse, sexual abuse and emotional abuse) and neglect – is a major public health issue worldwide. A history of child maltreatment is known to be associated with adverse outcomes in adulthood across a number of domains, including psychiatric and physical health measures (Gilbert et al., 2009). Mood and anxiety disorders, such as major depressive disorder and post-traumatic stress disorder, have been shown in many studies to be associated with a history of prior child maltreatment (Banyard et al., 2001; Cutajar et al., 2010; Mills et al., 2016). Likewise, adolescent and adult substance use has been shown to be strongly associated with maltreatment in childhood (Afifi et al., 2012; Mills et al., 2017; Shin, 2012).

Cognitive and educational outcomes following child maltreatment have traditionally received somewhat less research attention than mood, anxiety and substance use disorders. However, the available evidence suggests that child maltreatment is associated with poorer cognitive and academic outcomes (Eckenrode et al., 1993; Leiter, 2007; Perez and Widom, 1994). The limited literature that is available also suggests that childhood maltreatment is a risk factor for later unemployment (Gilbert et al., 2009). This is relevant because unemployment is an important social determinant of adult mental health (Allen et al., 2014). While an overall picture has emerged from such studies, many have methodological features that may limit the validity of the findings.

The first issue relates to the identification of cases of child maltreatment. Most studies utilise cross-sectional surveys to define exposure to child maltreatment – such retrospective self-report in adulthood of previous child maltreatment leaves open the possibility of recall bias (Lisak and Luster, 1994). Even longitudinal studies have obtained information about child maltreatment cross-sectionally (Boden et al., 2007), or by parent interview (Lansford et al., 2002) – this latter method carries the potential risk of social desirability bias (Bornstein et al., 2014). Use of government agency data to define exposure to child maltreatment has the potential benefit of objectivity and prospectivity. Such linkage between a studied cohort and agency records of maltreatment has been used with cohorts of maltreated children matched with controls, but only rarely with birth cohorts (Eckenrode et al., 1993; Nikulina et al., 2011).

A second issue affecting some studies is the lack of detailed sociodemographic data to permit adjustment for potential socioeconomic confounders (Chandy et al., 1996). Exposure to child maltreatment is known to be strongly associated with markers of socioeconomic disadvantage (Sidebotham and Heron, 2006). A birth cohort allows access to detailed sociodemographic information collected from birth or earlier, thus giving an indication of the child’s social milieu during the influential early years.

A third issue of relevance is the acknowledged tendency to place greater emphasis on studying abuse – particularly childhood physical and sexual abuse – than on child neglect (McSherry, 2007). Specifically in relation to cognitive and academic outcomes, this is being gradually addressed in the literature – for example, Nikulina et al. (2011), in a study of a matched cohort of court-documented neglect cases, found that child neglect, as well as family and neighbourhood poverty, was a predictor of lower academic achievement.

Finally, only a small number of studies have tracked cognitive and/or academic attainment into adulthood. In studying young adults, employment status becomes an important relevant outcome – both because of its association with prior educational attainment and also because it is an important sociodemographic characteristic that is associated with health and well-being (Autor, 2014; Davey et al., 1998). Youth unemployment – even more so than periods of unemployment later in life – is a significant predictor of mental health problems later in adulthood (Strandh et al., 2014).

This study extends previous work (Mills et al., 2011) that examined cognitive outcome at age 14 and its association with child maltreatment by following the cohort into young adulthood (21 years). This was the first study to our knowledge to examine cognitive outcomes in a birth cohort following different kinds of agency-documented child maltreatment – both abuse and neglect – prospectively. At age 14, both abuse and neglect were associated with lower cognitive function.

The aim of this study was to assess whether exposure to child maltreatment is associated with (1) reduced verbal intelligence in young adulthood (age 21), (2) failure to complete high school education and (3) lack of engagement in either formal study or employment at age 21.

Methods

The study follows participants from birth to age 21. The Mater-University of Queensland Study of Pregnancy (MUSP) is a birth cohort that commenced in 1981. Consecutive pregnant women – numbering 8556 – were invited to participate as they attended the Mater Misericordiae Mothers’ Hospital for their first prenatal visit (Keeping et al., 1989). After excluding multiple births, adoptions, perinatal deaths and withdrawal of consent, the cohort numbered 7223 mother and infant pairs (Najman et al., 2004). The outcomes of this study were collected in the 21-year follow-up phase, at which a total of 3778 (52.3%) offspring completed the main questionnaire. Prior to age 21, staged follow up of mothers and children had occurred at 3–5 days, 6 months, 5 years and 14 years (Najman et al., 2015).

Outcome measures

To examine the cognitive, educational and employment outcomes of the young adults, a number of key measures were recorded at age 21. The Peabody Picture Vocabulary Test (PPVT) is a validated instrument that provides a measure of receptive verbal intelligence. This is an important predictor of academic success, which in turn is associated with increased well-being in adulthood (Hogan et al., 2010). Young adults completed the PPVT in person, administered separately from the main questionnaire. The test is standardised to a mean score of 100, with standard deviation of 10.

In the 21-year questionnaire, young adults were also asked to select their highest level of education completed. For this analysis, a dichotomous outcome was used, based on completion of high school versus failure to complete high school.

Finally, a young person’s status as either being employed or engaged in formal study was considered an important outcome at age 21 given the recognised adverse psychological correlates of unemployment (Fergusson et al., 2014). In the 21-year questionnaire, study subjects were asked, ‘In the last week did you have a full time or part time job of any kind?’ and selected from six options ranging from ‘Yes, worked full time for payment or profit’ to ‘No, did not have a job’. Participants were also asked about their current educational status – ‘Are you attending school or any other educational institution?’ Subjects who selected both ‘No, did not have a job’ and were not attending school or an educational institution were categorised as neither employed nor studying, with the comparison group being all the other young people who had indicated at least part-time work or study.

Child maltreatment variables

The child maltreatment data for this study were obtained from the records of the state child protection agency (Department of Families, Youth and Community Care – DFYCC) in September 2000, when the youngest members of the cohort were 16.5 years old. The MUSP longitudinal data were linked anonymously to the DFYCC records as reported previously (Strathearn et al., 2009). Each time the agency received a notification about possible child maltreatment (e.g. from a school, health professional or the public), an investigation commenced. If the investigation confirmed that abuse or neglect had occurred, or that the child was at unacceptable risk, the outcome was recorded as ‘Substantiated’ or ‘Substantiated, at risk’, along with the type or types of maltreatment – physical, sexual or emotional abuse, and neglect – that were substantiated. In this study, exposure to child maltreatment is defined by the occurrence of one or more substantiated reports to DFYCC prior to September 2000.

The young people who had been subject to notified maltreatment were categorised into one or both of two non-exclusive groups: an abuse group, consisting of all who had been subject to a report for one or more of physical abuse, sexual abuse or emotional abuse; and a neglect group, consisting of all who had been notified as cases of neglect. Non-exclusive categorisation of maltreatment was utilised because it reflects the fact that most children and young people are notified as suspected cases of more than one type of maltreatment – as previously reported in this cohort, more than one type of abuse was documented for two-thirds of those notified (Mills et al., 2013).

Potential confounding variables

The results of initial bivariate analyses were adjusted for known or suspected confounders, based on their known association with cognitive function and/or child maltreatment. While some degree of mediating function of these covariates cannot be excluded, they were considered more plausible as confounders. The first stage of adjustment was for age and sex. For the second stage, the following relevant sociodemographic variables were added to the adjustment: family income and maximum maternal education level achieved (collected at the first prenatal visit); the child’s birthweight z score and requirement for neonatal intensive care admission; and maternal tobacco and alcohol use during pregnancy. In addition, duration of breast feeding, a characteristic known to be associated with improved cognitive outcome, was added to the analytic model (Kramer et al., 2008).

Statistical analysis

For dichotomous outcomes, associations with child maltreatment are presented as odds ratios, and for the continuous outcome (PPVT) unstandardised regression coefficients are presented. Multivariable logistic regression analysis was performed using SPSS (IBM, New York). The non-exclusive categorisation of agency-notified child abuse (physical, emotional and/or sexual) and child neglect was maintained in the analyses because of the high overlap between the groups as noted above.

To estimate the population impact of child maltreatment on the dichotomous outcomes (failure to complete high school and failure to be employed or studying at age 21), a population attributable risk (PAR) calculation was undertaken – the population prevalence of the risk factor (child maltreatment) was estimated from the prevalence of child maltreatment notification in the entire MUSP cohort (10.9%, n = 7223), and the relative risks of the outcomes calculated from the unadjusted data shown in Table 1. The study was approved by the University of Queensland Behavioural and Social Sciences Ethical Review Committee.

Table 1.

Unadjusted associations between child maltreatment and study outcomes.

	Peabody Picture Vocabulary Test		Failure to complete high school		Failure to be employed or in education at 21
	n	Mean score (SD; p)	n	% (p)	n	% (p)
No notified maltreatment	1998	97.2 (10.2; n/a)	3467	19.0 (n/a)	3454	12.8 (n/a)
Any notified maltreatment	152	92.9 (12.3; <0.001)	283	45.6 (<0.001)	285	31.9 (<0.001)
Abuse	127	91.9 (12.3; <0.001)	241	46.1 (<0.001)	243	31.7 (<0.001)
Neglect	69	93.0 (14.4; 0.002)	146	51.4 (<0.001)	148	32.4 (<0.001)
No substantiated maltreatment	2063	97.1 (10.2; n/a)	3582	19.7 (n/a)	3568	13.5 (n/a)
Any substantiated maltreatment	87	92.1 (13.3; <0.001)	168	48.8 (<0.001)	171	31.0 (<0.001)
Abuse	77	92.0 (12.3; <0.001)	142	48.6 (<0.001)	145	30.3 (<0.001)
Neglect	28	90.7 (19.1; <0.001)	71	56.3 (<0.001)	73	39.7 (<0.001)
Total	2150	96.9 (10.4)	3750	21.0	3739	14.3

SD: standard deviation.

Results

Cohort characteristics

Of the original birth cohort of 7223 mother-infant pairs, 3778 (52.3%) of the young people completed the main 21-year questionnaire. Of these, 3750 (99.3%) answered the question about high school completion, and 3739 (99.0%) the questions regarding current employment and study. The PPVT was completed by a smaller sample numbering 2150 (56.9% of remaining cohort), of whom 1916 – 50.7% of remaining cohort – had complete data available (Table 1).

Among the original cohort of 7223, 7214 had linked child protection data available. Of these, 789 (10.9%) were notified as suspected cases of maltreatment. The number substantiated as cases of maltreatment was 506 (7.0%).

Those who were more socially disadvantaged, and those with histories of child maltreatment, were more likely to be lost to follow-up, as reported previously (Mills et al., 2013). Thus, the rates of notified and substantiated child maltreatment were lower in the remaining cohort at age 21 when compared with the overall cohort – 7.6% and 4.6%, respectively.

PPVT

Table 1 shows the PPVT results (mean and SD) for the maltreated and non-maltreated subjects. In unadjusted analysis, exposure to agency-notified child maltreatment for any kind of maltreatment was associated with a lower PPVT outcome by nearly half a standard deviation and remained significant at over a quarter of a standard deviation after full adjustment for potential confounders (unstandardised coefficient = −2.85, 95% confidence interval [CI] = [–4.41, –0.82]; Table 2). Narrowing the definition of exposure to only those whose cases were substantiated produced a very similar result (Table 2). In terms of the subgroups, exposure to notified abuse was strongly associated with lower PPVT score, whereas notified neglect was not. However, in relation to substantiated cases, both abuse and neglect were similarly associated with a lower PPVT result (Table 2).

Table 2.

Peabody Picture Vocabulary Test outcomes according to child maltreatment status.

	Unadjusted coefficient [95% CI]	p	Adjusted coefficient^a [95% CI]	p	Adjusted coefficient^b [95% CI]	p
No maltreatment	0.0	n/a	0.0	n/a	0.0	n/a
Any notified maltreatment	−4.49 [−6.28, −2.46]	<0.001	−4.39 [−6.18, −2.37]	<0.001	−2.85 [−4.41, −0.82]	0.004
Abuse	−5.31 [−7.74, −3.56]	<0.001	−5.18 [−7.60, −3.43]	<0.001	−3.77 [−5.74, −1.81]	<0.001
Neglect	−2.71 [−6.76, –1.09]	0.007	−2.73 [−6.77, −1.10]	0.006	−1.94 [−5.26, 0.03]	0.053
No maltreatment	0.0	n/a	0.0	n/a	0.0	n/a
Any substantiated maltreatment	−3.95 [−7.47, −2.51]	<0.001	−3.90 [−7.39, −2.44]	<0.001	−2.52 [−5.31, −0.67]	0.012
Abuse	−3.68 [−7.61, −2.32]	<0.001	−3.59 [–7.49, −2.20]	<0.001	−2.26 [–5.34, −0.38]	0.024
Neglect	−2.93 [−11.51, −2.28]	0.003	−2.97 [−11.57, −2.36]	0.003	−2.14 [−8.97, −0.39]	0.033

CI: confidence interval.

Adjusted for age and sex.

Adjusted for age, sex, race, family income, maternal education, birthweight z score, neonatal intensive care admission, maternal tobacco and alcohol use in pregnancy, breast feeding.

High school completion

Among the entire cohort of young people at age 21, 21.0% had not completed high school (Table 1). Exposure to notified child maltreatment was significantly associated with failure to complete high school, both before and after adjustment for potential confounders – after adjustment the group notified as maltreatment cases had more than triple the odds of incomplete high school education (Table 3). The association was similarly strong when narrowed to only substantiated cases (Table 3). Likewise, exposure to both abuse and neglect were strongly associated with failure to complete high school (Table 3). The proportion of failure of high school completion attributable to notified child maltreatment (PAR) was calculated as 13.2%.

Table 3.

Failure to complete high school according to child maltreatment status.

	Unadjusted odds ratio [95% CI]	p	Adjusted odds ratio^a [95% CI]	p	Adjusted odds ratio^b [95% CI]	p
No maltreatment	1.0	n/a	1.0	n/a	1.0	n/a
Any notified maltreatment	3.54 [2.68, 4.68]	<0.001	3.64 [2.75, 4.82]	<0.001	3.12 [2.33, 4.17]	<0.001
Abuse	3.63 [2.70, 4.88]	<0.001	3.75 [2.78, 5.06]	<0.001	3.22 [2.36, 4.39]	<0.001
Neglect	4.34 [2.96, 6.36]	<0.001	4.39 [2.98, 6.44]	<0.001	3.62 [2.43, 5.38]	<0.001
No maltreatment	1.0	n/a	1.0	n/a	1.0	n/a
Any substantiated maltreatment	4.25 [3.00, 6.02]	<0.001	4.28 [3.01, 6.08]	<0.001	3.59 [2.50, 5.16]	<0.001
Abuse	4.18 [2.87, 6.09]	<0.001	4.33 [2.96, 6.32]	<0.001	3.64 [2.47, 5.39]	<0.001
Neglect	5.40 [3.11, 9.36]	<0.001	5.40 [3.10, 9.38]	<0.001	4.42 [2.51, 7.80]	<0.001

CI: confidence interval.

Adjusted for age and sex.

Adjusted for age, sex, race, family income, maternal education, birthweight z score, neonatal intensive care admission, maternal tobacco and alcohol use in pregnancy, breast feeding.

Current study or employment

Among the total cohort at age 21, 14.3% were neither studying nor employed. Exposure to notified child maltreatment was significantly associated with failure to be either studying or employed at age 21 – after adjustment, the group notified as cases of child maltreatment had more than double the odds of being neither employed nor studying (Table 4). The results were similar when restricted to substantiated cases of maltreatment (Table 4). Both abuse and neglect were strongly associated with failure to be in either education or employment (Table 4). The PAR was 14.0%.

Table 4.

Failure to be either in education or employment at age 21, according to child maltreatment status.

	Unadjusted odds ratio [95% CI]	p	Adjusted odds ratio^a [95% CI]	p	Adjusted odds ratio^b [95% CI]	p
No maltreatment	1.0	n/a	1.0	n/a	1.0	n/a
Any notified maltreatment	3.01 [2.22, 4.08]	<0.001	2.95 [2.17, 4.01]	<0.001	2.38 [1.73, 3.27]	<0.001
Abuse	2.96 [2.14, 4.10]	<0.001	2.87 [2.07, 3.98]	<0.001	2.29 [1.63, 3.21]	<0.001
Neglect	2.92 [1.93, 4.42]	<0.001	2.92 [1.92, 4.44]	<0.001	2.33 [1.51, 3.59]	<0.001
No maltreatment	1.0	n/a	1.0	n/a	1.0	n/a
Any substantiated maltreatment	2.83 [1.93, 4.15]	<0.001	2.81 [1.91, 4.14]	<0.001	2.22 [1.49, 3.30]	<0.001
Abuse	2.66 [1.75, 4.03]	<0.001	2.56 [1.68, 3.89]	<0.001	1.97 [1.28, 3.03]	0.002
Neglect	3.86 [2.21, 6.75]	<0.001	3.84 [2.18, 6.77]	<0.001	3.13 [1.74, 5.61]	<0.001

CI: confidence interval.

Adjusted for age and sex.

Adjusted for age, sex, race, family income, maternal education, birthweight z score, neonatal intensive care admission, maternal tobacco and alcohol use in pregnancy, breast feeding.

Discussion

This study has shown that exposure to child maltreatment is associated with adverse cognitive, educational and employment outcomes in young adulthood. This is the first study to our knowledge to examine cognitive and educational outcomes into adulthood using a birth cohort design linked with government agency maltreatment data. The strengths of the study include the longitudinal design, detailed information about likely confounders and the objectivity of access to government agency data about exposure to child maltreatment. Furthermore, the ability to examine the outcomes following not just physical or sexual abuse, but also neglect, is important.

The noted associations are strong and statistically significant. The results are also of public health significance – for example, even after adjustment the PPVT in the maltreatment group was more than a quarter of a standard deviation lower than in non-maltreated individuals. By analogy with other standardised tests of intelligence, this approximates to 2–3 IQ points. Likewise, the maltreated group had more than three times the odds of failure to complete high school and more than double the odds of neither working nor studying at age 21. The population risks of failure to complete high school and failure to be employed or studying at age 21 attributable to notified child maltreatment (13.2% and 14.0%, respectively) support the importance of child maltreatment as a major public health issue.

The findings build on the existing child maltreatment literature in a number of ways. Most previous studies on educational outcomes have been limited to the adolescent age group (e.g. Eckenrode et al., 1993; Mills et al., 2011), and occupational outcomes in adulthood have been very rarely studied (Gilbert et al., 2009). In addition, the birth cohort design supports applicability of the findings on a population health basis, whereas several previous studies have followed subjects with documented maltreatment from later childhood and relied on matched controls for comparison (e.g. Eckenrode et al., 1993; Noll et al., 2010; Trickett et al., 2011).

Among the previous studies of cognitive and academic outcomes following child maltreatment, some have found that adjustment for sociodemographic confounders reduced the observed associations to non-significance (e.g. Boden et al., 2007; Nightingale and Walker, 1991), while most others have reported robust associations that persisted after adjustment (e.g. Kerr et al., 2000; Nikulina et al., 2011). This study, with the detailed sociodemographic information available from the MUSP birth cohort, falls into the latter category, albeit with some expected attenuation of the point estimates of association that indicate the important role of social determinants of mental health outcomes (Allen et al., 2014).

One of the key findings of an earlier study of this cohort at age 14 was that both child abuse (physical, sexual and/or emotional) and neglect were associated with adverse cognitive outcomes at age 14 (Mills et al., 2011). This theme continues to be supported by the present findings at age 21, with the caveat that mutual adjustment of abuse for neglect and vice versa was not undertaken at 21 (as it was at age 14) due to the high overlap of the groups and falling numbers of cases – especially neglect – with further cohort attrition between the 14- and 21-year follow-up. The ‘neglect of neglect’, that is, the tendency to orient research efforts towards physical and sexual abuse to the relative exclusion of child neglect (Kendall-Tackett and Eckenrode, 1996), continues to be relevant in the literature, and this study adds further impetus to study child neglect as an important public health issue.

Despite the significant association between child maltreatment and adverse outcomes in young adulthood, the direction of the association requires consideration. Rather than adverse cognitive outcome simply being a consequence of child maltreatment, it is possible that children with lower genetic potential for cognitive development are at higher risk of experiencing abuse or neglect, for example, because of particular behavioural features. This possibility is suggested by existing literature indicating that children with disability of any kind (physical, cognitive or emotional) are at increased risk of maltreatment (Hibbard et al., 2007). Nevertheless, based on the existing literature, and the population base of the present study, it is likely that the principal direction of association is that child maltreatment may lead to reduced cognitive outcomes due to lack of stimulating environments and attentive parenting (Eckenrode et al., 1993; Leiter, 2007; Maguire et al., 2015).

Despite the robust methodology, there are a number of limitations that require acknowledgement. The ability to adjust for important potential confounders such as socioeconomic status and neonatal variables is a strength of the study, but there remains the possibility that unmeasured confounders still exist. One example is detailed information about the fathers – paternal education may be relevant to a child’s academic outcomes, and particularly so in the present context given that fathers and step-fathers may be implicated as perpetrators of child maltreatment in a proportion of cases.

The reliance on government agency child maltreatment data, while conferring prospectivity and objectivity to the allocation of subjects to maltreatment groups, brings with it some potential limitations. Most notably, reports to government agencies almost certainly underestimate the true incidence of child abuse and neglect. Thus, it is likely that there is some degree of misallocation in this study, particularly with maltreated children being included in the non-maltreated group. While this is a potential limitation, the effect of such misallocation is to reduce the size of observed associations. This suggests that our point estimates of association are likely to be conservative.

Finally, while the overall rate of follow-up at the 21-year phase (52.3%) is reasonable for a birth cohort, any possible effect of the non-random increased attrition of socially disadvantaged and maltreated young people requires consideration. Recent research suggests that such differential attrition makes little difference to the reliability of point estimates of association among the remaining subjects (Wolke et al., 2009), and previous experience in the MUSP cohort suggests that the addition of statistical techniques such as multiple imputation makes little difference to either the estimates or their precision (Najman et al., 2015).

This study lends further support to research and policy goals that aim to prevent, and mitigate the effects of, child maltreatment. Programmes to help prevent child maltreatment can include preventive nurse home visiting programmes (Olds et al., 1997) and early years parenting training (Prinz et al., 2009). Mitigation of the adverse educational and employment outcomes experienced by maltreated young people can commence early in life when maltreatment has already been identified. For example, the relatively simple measure of enrolling a maltreated young child in high quality early childhood education has been shown in a national US survey to have efficacy in improving the children’s language scores when compared with maltreated children not enrolled in such a programme (Merritt and Klein, 2015). This is despite the effects of trauma experience and pre-existing developmental impairments on their ability to engage with the educational curriculum (Merritt and Klein, 2015).

Improving the educational and occupational attainment of maltreated adolescents may be more achievable than previously suspected, in the context of recent research confirming that verbal intelligence is subject to more change in adolescence than previously thought (Ramsden et al., 2011). An example of a programme promoting post-secondary education for youth in foster care is Better Futures, a randomised trial of a programme of interventions such as a Summer school and educational mentoring, described by Phillips et al. (2015). The early findings are promising, and particularly relevant, because the youth had high rates of mental health problems – almost three quarters were receiving mental health services. This suggests that even in the context of the multiple disadvantage (cognitive, educational and mental health) experienced by maltreated youth, a focus on continuing education is worthwhile.

Conclusion

Child maltreatment, as defined by government-agency notification and substantiation, is associated with poorer verbal cognition, lower rates of high school completion and higher rates of being both unemployed and not studying at age 21. These findings demonstrate that previous findings of lower cognitive function among maltreated young people in this cohort at age 14 are sustained into young adulthood and have social and educational consequences. The findings add impetus to efforts to prevent child maltreatment and implement programmes to ameliorate adverse cognitive outcomes in children who have been exposed to child maltreatment.

Footnotes

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

This study was primarily funded by the National Health and Medical Research Council (NHMRC), Australia. The content is solely the responsibility of the authors and does not necessarily represent the official views of the US National Institutes of Health, the Australian National Health and Medical Research Council, or the other supporting agencies.

ORCID iD

Lane Strathearn

References

Afifi

Henriksen

Asmundson

GJG

et al . (2012) Childhood maltreatment and substance use disorders among men and women in a nationally representative sample. Canadian Journal of Psychiatry 57: 677–686.

Allen

Balfour

Bell

et al . (2014) Social determinants of mental health. International Review of Psychiatry 26: 392–407.

Autor

(2014) Skills, education, and the rise of earnings inequality among the ‘other 99 percent’. Science 344: 843–851.

Banyard

Williams

Siegel

(2001) The long-term mental health consequences of child sexual abuse: An exploratory study of the impact of multiple traumas in a sample of women. Journal of Traumatic Stress 14: 697–715.

Boden

Horwood

Fergusson

(2007) Exposure to childhood sexual and physical abuse and subsequent educational achievement outcomes. Child Abuse & Neglect 31: 1101–1114.

Bornstein

Putnick

Lansford

et al . (2014) Mother and father socially desirable responding in nine countries: Two kinds of agreement and relations to parenting self-reports. International Journal of Psychology 50: 174–185.

Chandy

Blum

Resnick

(1996) Female adolescents with a history of sexual abuse: Risk outcome and protective factors. Journal of Interpersonal Violence 11: 503–518.

Cutajar

Mullen

Ogloff

JRP

et al . (2010) Psychopathology in a large cohort of sexually abused children followed up to 43 years. Child Abuse & Neglect 34: 813–822.

Davey

Hart

Hole

et al . (1998) Education and occupational social class: Which is the more important indicator of mortality risk? Journal of Epidemiology and Community Health 52: 153–160.

10.

Eckenrode

Laird

Doris

(1993) School performance and disciplinary problems among abused and neglected children. Developmental Psychology 29: 53–62.

11.

Fergusson

McLeod

Horwood

(2014) Unemployment and psychosocial outcomes to age 30: A fixed-effects regression analysis. Australian and New Zealand Journal of Psychiatry 48: 735–742.

12.

Gilbert

Widom

Browne

et al . (2009) Burden and consequences of child maltreatment in high-income countries. Lancet 373: 68–81.

13.

Hibbard

Desch

American Academy of Pediatrics Committee on Child Abuse and Neglectet al. (2007) Maltreatment of children with disabilities. Pediatrics 119: 1018–1025.

14.

Hogan

Parker

JDA

Wiener

et al . (2010) Academic success in adolescence: Relationships among verbal IQ, social support and emotional intelligence. Australian Journal of Psychology 62: 30–41.

15.

Keeping

Najman

Morrison

et al . (1989) A prospective longitudinal study of social, psychological and obstetric factors in pregnancy: Response rates and demographic characteristics of the 8556 respondents. British Journal of Obstetrics and Gynaecology 96: 289–297.

16.

Kendall-Tackett

Eckenrode

(1996) The effects of neglect on academic achievement and disciplinary problems: A developmental perspective. Child Abuse & Neglect 20: 161–169.

17.

Kerr

Black

Krishnakumar

(2000) Failure-to-thrive, maltreatment and the behavior and development of 6-year-old children from low-income, urban families: A cumulative risk model. Child Abuse & Neglect 24: 587–598.

18.

Kramer

Fombonne

Igumnov

et al . (2008) Effects of prolonged and exclusive breastfeeding on child behavior and maternal adjustment: Evidence from a large, randomized trial. Pediatrics 121: e435–e440.

19.

Lansford

Dodge

Pettit

et al . (2002) A 12-year prospective study of the long-term effects of early child physical maltreatment on psychological, behavioral, and academic problems in adolescence. Archives of Pediatrics & Adolescent Medicine 156: 824–830.

20.

Leiter

(2007) School performance trajectories after the advent of reported maltreatment. Children and Youth Services Review 29: 363–382.

21.

Lisak

Luster

(1994) Educational, occupational, and relationship histories of men who were sexually and/or physically abused as children. Journal of Traumatic Stress 7: 507–523.

22.

McSherry

(2007) Understanding and addressing the ‘neglect of neglect’: Why are we making a mole-hill out of a mountain? Child Abuse & Neglect 31: 607–614.

23.

Maguire

Williams

Naughton

et al . (2015) A systematic review of the emotional, behavioural and cognitive features exhibited by school-aged children experiencing neglect or emotional abuse. Child: Care, Health and Development 41: 641–653.

24.

Merritt

Klein

(2015) Do early care and education services improve language development for maltreated children? Evidence from a national child welfare sample. Child Abuse & Neglect 39: 185–196.

25.

Mills

Alati

O’Callaghan

et al . (2011) Child abuse and neglect and cognitive function at 14 years of age: Findings from a birth cohort. Pediatrics 127: 4–10.

26.

Mills

Kisely

Alati

et al . (2016) Self-reported and agency-notified sexual abuse in a population-based birth cohort. Journal of Psychiatric Research 74: 87–93.

27.

Mills

Kisely

Alati

et al . (2017) Child maltreatment and cannabis use in young adulthood: A birth cohort study. Addiction 112: 494–501.

28.

Mills

Scott

Alati

et al . (2013) Child maltreatment and adolescent mental health problems in a large birth cohort. Child Abuse & Neglect 37: 292–302.

29.

Najman

Aird

Bor

et al . (2004) The generational transmission of socioeconomic inequalities in child cognitive development and emotional health. Social Science & Medicine 58: 1147–1158.

30.

Najman

Alati

Bor

et al . (2015) Cohort profile update: The Mater-University of Queensland Study of Pregnancy (MUSP). International Journal of Epidemiology 44: 78–78f.

31.

Nightingale

Walker

(1991) The impact of social class and parental maltreatment on the cognitive functioning of children. Journal of Family Violence 6: 115–130.

32.

Nikulina

Widom

Czaja

(2011) The role of childhood neglect and childhood poverty in predicting mental health, academic achievement and crime in adulthood. American Journal of Community Psychology 48: 309–321.

33.

Noll

Shenk

Yeh

et al . (2010) Receptive language and educational attainment for sexually abused females. Pediatrics 126: e615–e622.

34.

Olds

Eckenrode

Henderson

et al . (1997) Long-term effects of home visitation on maternal life course and child abuse and neglect. JAMA 278: 637–643.

35.

Perez

Widom

(1994) Childhood victimization and long-term intellectual and academic outcomes. Child Abuse & Neglect 18: 617–633.

36.

Phillips

Powers

Geenen

et al . (2015) Better futures: A validated model for increasing postsecondary preparation and participation of youth in foster care with mental health challenges. Children and Youth Services Review 57: 50–59.

37.

Prinz

Sanders

Shapiro

et al . (2009) Population-based prevention of child maltreatment: The U.S. Triple P System population trial. Prevention Science 10: 1–12.

38.

Ramsden

Richardson

Josse

et al . (2011) Verbal and non-verbal intelligence changes in the teenage brain. Nature 479: 113–116.

39.

Shin

(2012) A longitudinal examination of the relationships between childhood maltreatment and patterns of adolescent substance use among high-risk adolescents. American Journal on Addictions 21: 453–461.

40.

Sidebotham

Heron

(2006) Child maltreatment in the ‘children of the nineties’: A cohort study of risk factors. Child Abuse & Neglect 30: 497–522.

41.

Strandh

Winefield

Nilsson

et al . (2014) Unemployment and mental health scarring during the life course. European Journal of Public Health 24: 440–445.

42.

Strathearn

Mamun

Najman

et al . (2009) Does breastfeeding protect against substantiated child abuse and neglect? A 15-year cohort study. Pediatrics 123: 483–493.

43.

Trickett

Kim

Prindle

(2011) Variations in emotional abuse experiences among multiply maltreated young adolescents and relations with developmental outcomes. Child Abuse & Neglect 35: 876–886.

44.

Wolke

Waylen

Samara

et al . (2009) Selective drop-out in longitudinal studies and non-biased prediction of behaviour disorders. British Journal of Psychiatry 195: 249–256.