The purpose of this study was to examine the predictive relationship between early parenting stress and later child disruptive behavior in a high-risk sample of children, including children with prenatal cocaine exposure. Results suggest that early parenting stress at 4 months significantly predicted child disruptive behavior at 36 months over and above several covariates, including maternal age, SES, child gender and race, prematurity status, and infant temperament. Both infant temperament and parenting stress had unique and independent effects on disruptive behavior suggesting that while early child characteristics are related to later child behavior, parenting stress may also maintain or perhaps exacerbate behavior. Follow-up analyses using other subscales of infant temperament led to similar findings. Parenting stress at 4 months accounted for an additional 2% of the variance in caregiver-reported child disruptive behavior above the several covariates.
These results are similar to previous research demonstrating the relationship between parenting stress and child behavior in a typically developing sample [8
] and extend these findings to a sample of high-risk children. Maternal report of child behavior, however, was not different between children exposed to cocaine and matched controls. This finding was inconsistent with previous results of MLS [26
], but the current study excluded children from unstable home placements that may have influenced the development of disruptive behavior. There was no difference in the relationship between parenting stress and child behavior among children prenatally exposed to cocaine and matched controls, suggesting that cocaine exposure does not influence the impact of early parenting stress on later child behavior in this sample. The lack of a significant difference between exposed and unexposed groups may be due to the high-risk nature of the sample. For example, rates of CBCL scores in the clinically significant range across the entire sample were considerably higher than would be expected in a normative sample. Similar to previous research [19
], cocaine effects in this sample may not be visible in the face of multiple and cumulative risk factors. Overall, the results illustrate the development of disruptive behavior in a high-risk sample of children and highlight the fact the prevention and early intervention efforts can build directly on work in other populations.
Caregivers of the children in the cocaine-exposed group did not report higher levels of parenting stress than caregivers of children in the control group. However, rates of clinically significant scores on the parental distress subscale across the entire sample were relatively high (i.e., 25% ≥ 85th
percentile). Despite the high rates overall, the lack of differences between groups were surprising and inconsistent with a previous study demonstrating significantly higher levels of parenting stress among substance-abusing mothers [10
]. These conflicting findings may be due to potential differences between biological mothers and caregivers of children prenatally exposed to cocaine. The biological mothers who abused substances may experience unique stressors that are not evident in non-biological caregivers. However, the majority of caregivers in both groups were the biological mothers, and follow-up analyses suggested this factor did not affect our findings.
Additionally, mothers in the comparison sample in the current study had a history of other drug use (e.g., alcohol, marijuana, and nicotine) whereas mothers in the former study [10
] had no known history of substance abuse. The use of other substances puts the comparison sample at further risk, and it would be difficult to find a unique effect of cocaine between two groups with multiple risk factors and overall high levels of parenting stress. Warner and colleagues [18
] demonstrated similar findings with caregiver depression. Although depression predicted child disruptive behavior at 36 months, there was no significant difference in caregiver depression between cocaine-exposed and comparison groups. We conducted follow-up analyses in the current study and also found no differences in caregiver depression. In sum, the inconsistent findings in the literature highlight the need for future research examining differences in parenting stress among high-risk exposed and comparison samples.
For this study, we delineated specific criteria for the inclusion of participants drawn from the larger MLS sample. Caregivers changed frequently in this sample due to out-of-home placement and other related factors. This poses a methodological challenge to examining the specific effects of parenting stress of a single caregiver over time. Thus, we only included children who had the same caregiver at both 4 and 36 months without any evidence of change in caregiver status between those time points. Although this decreased our sample size from the full MLS sample, the resulting sample was large enough to allow for sufficient statistical power. One potential limitation, however, is that the selection of the analysis sample for this study could reduce the generalizability of our findings. Nonetheless, the consistent caregivers over time lend greater credence to the relationship between early parenting stress and later child behavior. Other strengths of the study include a large sample size, use of well-validated measures of parenting stress and child behavior, and inclusion of a control group matched on prematurity, race, and sex.
Despite the methodological strengths of the current study, there are some limitations that need to be addressed. First, children who were excluded from this study were more likely to be in the cocaine-exposed group. In addition, the primary caregivers excluded from the study had lower SES and higher rates of two specific domains of parenting stress (i.e., parental distress and parent-child dysfunctional interaction). These differences may explain the non-significant interaction effect between cocaine exposure and parenting stress because the most severe dyads may have been excluded. However, we re-ran the regression with the entire sample and found the same results in that early parenting stress predicts later child externalizing behavior but is not influenced by cocaine exposure.
Second, the use of caregiver report of child disruptive behavior is subject to rater bias and only represents one of many modes to assess child behavior. Direct observation of child behavior could provide more objective data, and teacher report could help confirm the presence of disruptive behavior in a preschool setting. A third limitation of the current study is the inability to control for all potential predictors of later child disruptive behavior. For example, genetics may play a significant role in the development of disruptive behavior disorders and was not measured in the current study. In addition, the current study does not include infant data prior to 4 months, which may also impact parenting stress and child behavior. Finally, the entire sample was primarily low income and African American limiting the generalizability of these findings to other populations.
In sum, this study demonstrates a predictive relationship between early parenting stress and later child behavior in high-risk children with and without drug exposure. These findings help describe the development of disruptive behavior over the first 3 years and highlight the impact of parental experience on child outcome. Parents who report greater stress have been found to be more authoritarian and negative in their interactions with their child [27
], which increase the frequency of disruptive behaviors. Two large reviews of the past 40 years of the psychosocial treatment literature indicated parent-training interventions are the first line approach for the treatment of young children with disruptive behavior disorders [28
], and a parent training intervention has been shown to lead to decreases in parenting stress in other at-risk child populations [30
]. Given the current findings, parenting stress may be an important target of treatment that may impact on the transactional process and represents an important area of future research. Overall, the results highlight the need for early detection and intervention among parents with elevated levels of stress, regardless of history of substance abuse.