For a study, researchers sought to determine if pharmacologic therapy for newborn abstinence syndrome (NAS) was linked to changes in DNA methylation (DNAm) of the mu-opioid receptor gene (OPRM1) and improvements in neonatal neurobehavioral outcomes. About 37 infants had buccal swabs taken before and after morphine therapy for NAS. DNAm was tested at four cytosine-phosphate-guanine (CpG) positions within the OPRM1 gene using genomic DNA. The NICU Network Neurobehavioral Scales (NNNS) were also used to assess patients before and after NAS therapy. After that, changes in DNAm (DNAmpost-tx – DNAmpre-tx) and NNNS summary scores (NNNSpost-tx – NNNSpre-tx) were computed. Path analysis was performed to investigate the relationships between pharmacologic therapy (length of treatment [LOT] and total morphine dosage), changes in DNAm, and changes in NNNS summary scores.

At one of four CpG positions within the OPRM1 gene, DNAm was considerably reduced from pretreatment to posttreatment. From pretreatment to posttreatment, neonates showed decreased excitability, hypertonia, lethargy, symptoms of stress and abstinence, and improved movement quality and control. Longer LOT and higher morphine dosage were linked with larger DNAm declines; greater DNAm decreases were associated with increased excitability and hypertonia on the NNNS. Pharmacologic therapy of NAS is linked to lower DNAm of the OPRM1 gene and better infant neurobehavioral outcomes. These alterations in newborn neurobehavior may be influenced by epigenetic modifications.