The dopamine receptor D4 gene (DRD4) 7-repeat allele has been found to interact with environmental factors such as parenting in children and peer attitudes in adults to influence aspects of behavior such as risk taking. We previously found that in toddlers, lower-quality parenting in combination with the 7-repeat allele of the DRD4 gene was associated with greater parent-reported Sensation Seeking (SS), but was unrelated to Effortful Control (EC). We now report findings from a followup assessment with the same sample of children showing that parenting quality interacts with the presence of the 7-repeat allele to predict EC in 3- to 4-year-old children. The change in these patterns of results may reflect the increased role of the executive attention network in older children and adults. However, due to the small sample size (
Many studies suggest that the 7-repeat allele of the dopamine receptor D4 gene (DRD4) interacts with environmental factors to predict sensation seeking and externalizing behaviors in children and adults [
Many studies argue for the hypothesis that variations in DRD4 alter a child’s susceptibility to environmental factors [
In a previously published study of 18- to 21-month-old children, we examined how parenting quality and DRD4 interact to predict two aspects of temperament [
Subsequently, we found that the control system used by toddlers at 18 to 21 months was not the executive system but rather the orienting system [
The procedures in this experiment were approved by the Institutional Review Board of the University of Oregon that assured compliance with ethical considerations of the Helsinki Declaration. All parents signed informed consent forms that included their permission for publication of the overall results without identification of individuals.
Data for the current study are from an ongoing longitudinal study of the development of attention and temperament conducted at the University of Oregon. Families were recruited from the local community, and children were first brought into the laboratory at 7 to 9 months of age, returning at 18 to 21 months, and again at 3 to 4 years of age. These assessments are referred to as the time 1, time 2, and time 3 assessments, respectively. Methods and data reported here are from the time 2 and time 3 assessments. Other aspects of the time 1 and time 2 assessments have been reported in previous publications [
At time 2, caregivers had completed the early childhood behavior questionnaire (ECBQ; [
At time 3, parents were asked to complete the children’s behavior questionnaire (CBQ; [
Parenting quality was assessed at time 2 using a videotaped free-play procedure and a rating scheme adapted from the NICHD Study of Early Child Care (1993; reported previously in [
Genomic DNA was prepared from buccal cell samples taken from each child at time 2 using QuickExtract DNA extraction solution (Epicentre Biotechnologies, Madison, WI). The DRD4 variable number tandem repeat (VNTR) polymorphism was amplified using 0.2
Based on the genotyping procedure, children were divided into either the 7-repeat present group (individuals with 1 or 2 copies of the 7-repeat allele;
Descriptive statistics and correlations are presented in Table
Descriptive statistics and correlations.
Correlations | ||||||
---|---|---|---|---|---|---|
M | SD | (1) | (2) | (3) | (4) | |
Time 2 - parenting observation | ||||||
(1) Parenting quality | 5.21 | .88 | 1.00 | |||
Time 3 - CBQ temperament scales | ||||||
(2) Sensation seeking | 4.86 | .79 | .00 | 1.00 | ||
(3) Effortful control | 4.79 | .90 | −.02 | −.61* | 1.00 | |
(4) Negative affect | 3.87 | .84 | .03 | −.33* | .10 | 1.00 |
Summary of regression models.
Time 3 - CBQ temperament scales | |||
---|---|---|---|
Dependent variables | Sensation Seeking | Effortful Control | Negative Affect |
Step 1 | |||
Adjusted |
−.03 | −.04 | −.03 |
Degrees of freedom | 2, 49 | 2, 49 | 2, 49 |
Sig. |
.71 | .87 | .70 |
Sex of child | |||
Standardized beta | −.04 | −.05 | −.04 |
Significance | .80 | .71 | .81 |
Age of child at T3 | |||
Standardized beta | .11 | .05 | −.12 |
Significance | .44 | .71 | .42 |
Step 2 | |||
Adjusted |
−.01 | −.05 | −.02 |
Degrees of freedom | 2, 47 | 2, 47 | 2, 47 |
Sig. |
.29 | .57 | .32 |
DRD4 7-repeat status | |||
Standardized beta | −.20 | .14 | .22 |
Significance | .16 | .33 | .14 |
Parenting quality | |||
Standardized beta | .10 | .07 | .03 |
Significance | .51 | .65 | .83 |
Step 3 | |||
Adjusted |
−.02 | .08 | −.04 |
Degrees of freedom | 1, 46 | 1, 46 | 1, 46 |
Sig. |
.44 | .008* | .66 |
DRD4 7-R X parenting quality | |||
Standardized beta | −.14 | .47 | .08 |
Significance | .44 | .008* | .66 |
At time 3, there was no evidence of significant DRD4 × Parenting quality interaction predicting either SS or Negative Affect. There was, however, a significant interaction predicting EC. This interaction is plotted in Figure
Gene by environment interaction showing EC ratings as a function of quality of parenting and the presence or absence of the 7-repeat allele of the DRD4 gene. Parenting quality is a continuous variable in the analyses. The shape of this interaction is illustrated here using the overall mean, parenting below the 25th percentile (lower-quality parenting) and parenting above the 75th percentile (higher-quality parenting).
We found a significant G × E interaction indicating that parenting quality was positively associated with EC in the presence, but not the absence, of the DRD4 7-repeat allele. This was the relationship we had failed to find at the age of 18 to 21 months, but now it seems to be present in children at 3 to 4 years of age. It should be noted, however, that due to the small sample size and the novelty of the results, these findings should be treated with caution and considered preliminary until they are replicated in an independent sample. Additionally, since the results are preliminary, the discussion that follows is speculative.
The observed interaction may provide a possible mechanism by which the DRD4 7-repeat allele interacts with environmental influences. EC as measured in childhood has been repeatedly found to correlate with the child’s ability to resolve conflict during cognitive tasks [
Recently, we argued that control mechanisms shift during early childhood [
How could the executive network be influenced by parenting, peers, and other diverse environmental factors? The DRD4 gene encodes a dopamine receptor, and the 7-repeat allele is associated with reduced expression [
On the other hand, in this study, we did not find the G × E interaction relating the presence of the DRD4 gene and parenting to SS that was found earlier. However, there was a significant negative correlation between EC and SS, perhaps indicating that by this age, the executive attention system related to EC serves to regulate behaviors relating to SS. These findings could reflect developmental changes in control mechanisms that take place between 18 months and 4 years.
Our conceptualization of the DRD4 gene and the development of the executive network has broad implications for studying self-regulation and associated difficulties such as attention deficit hyperactivity disorder (ADHD). Recent studies of ADHD children using the Attention Network Test have shown abnormalities in the alerting and executive networks [
If the DRD4 gene is moderating the influence of socialization practices, then we might expect that associations between the 7-repeat and phenotypic outcomes will change as the child develops, and the focus of parenting efforts is altered to meet new challenges. There is considerable development of EC between 2 and 4 years of age [
Intervention studies have attempted to examine how individual differences, including genetic variation, influence early child development [
EC and executive attention [
At the age of 18 to 21 months, a G × E interaction was not found for children’s EC as measured by questionnaire. However, in this paper, we report that parenting quality interacts with the presence of the 7-repeat allele to determine EC in 3-4-year-old children. The change between 21 months and 3-4 years may reflect the increased connectivity and separation of the executive network in older children and adults. However, due to the small sample size and the novelty of the results, these findings should be treated with caution and considered preliminary until they are replicated in an independent sample.
B. E. Sheese ran the study, analyzed the data, and wrote a first draft of the paper; M. I. Posner and M. K. Rothbart conceived and designed the study and rewrote the paper; P. M. Voelker performed the genotyping, helped with the genetic analysis, and helped write the paper.
This paper was supported by NICHD Grant HD 060653 to Georgia State University and by an Illinois Wesleyan University ASD grant to the first author.