The dopamine D4 receptor gene, birth weight, maternal depression, maternal attention, and the prediction of disorganized attachment at 36 months of age: A prospective gene×environment analysis.

BACKGROUND: Efforts to understand the developmental pathways for disorganized attachment reflect the importance of disorganized attachment on the prediction of future psychopathology. The inconsistent findings on the prediction of disorganized attachment from the dopamine D4 receptor (DRD4) gene, birth weight, and maternal depression as well as the evidence supporting the contribution of early maternal care, suggest the importance of exploring a gene by environment model. METHODS: Our sample is from the Maternal Adversity, Vulnerability, and Neurodevelopment project; consisting of 655 mother-child dyads. Birth weight was cross-referenced with normative data to calculate birth weight percentile. Infant DRD4 genotype was obtained with buccal swabs and categorized according to the presence of the 7-repeat allele. Maternal depression was assessed with the Center for Epidemiologic Studies Depression Scale at the prenatal, 6-, 12-, and 24-month assessments. Maternal attention was measured at 6-months using a videotaped session of a 20-min non-feeding interaction. Attachment was assessed at 36-months using the Strange Situation Procedure. RESULTS: The presence of the DRD4 7-repeat allele was associated with less disorganized attachment, ß=-1.11, OR=0.33, p=0.0008. Maternal looking away frequency showed significant interactions with maternal depression at the prenatal assessment, ß=0.003, OR=1.003, p=0.023, and at 24 months, ß=0.004, OR=1.004, p=0.021, as at both time points, women suffering from depression and with frequent looking away behavior had an increased probability of disorganized attachment in their child, while those with less looking away behavior had a decreased probability of disorganized attachment in their child at 36 months. CONCLUSIONS: Our models support the contribution of biological and multiple environmental factors in the complex prediction of disorganized attachment at 36 months.

Preschool children without 7-repeat DRD4 gene more likely to develop disorganized attachment style.

BACKGROUND: The current paper aimed to explore the effects of birth weight and the 7-repeat allele in Exon III of the dopamine D4 receptor (DRD4) gene on the development of disorganized attachment, a potential endophenotype of depression. Infants born with low birth weight have been shown to be at higher risk for later neurological impairments, psychological disorders or behavioural problems. The DRD4 gene is critical for the cognitive and emotional processes that are sub-served by neural circuits in the prefrontal cortex. This paper examined the main effect of birth weight and DRD4 on the development of disorganized attachment. METHODS: Data was used from the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) project. The sample consisted of 251 mother-child dyads with complete data. Attachment style was assessed using the modified separation-reunion procedure. RESULTS: There was no main effect for birth weight on disorganized attachment, (b = -0.001, p = 0.998). There was, however, a main effect for the DRD4 7-repeat polymorphism on disorganized attachment (b = -1.120, p = 0.004). LIMITATIONS: Compared to studies of similar design, the sample size in this study was relatively small. Additionally, a significant number of subjects did not have complete data. CONCLUSIONS: Children without the DRD4 7-repeat allele were more likely to have disorganized attachment than children with the DRD4 7-repeat allele. This indicates that the 7-repeate allele of the DRD4 gene may actually serve as a protective factor against disorganized attachment.