A large number of drugs pass from the mothers’ blood stream through the placenta to the fetus. Drugs of abuse have a low molecular weight and lipid solubility making it easier to cross the placenta. When drugs or other substances of abuse are taken by the mother equilibrium is established between the materanal and fetal circulations. This in utero equilibrium provides a constant supply to the baby and with the mothers’ excretory and metabolic mechanisms the drug is cleared from the baby’s circulation. During this time, the fetus undergoes a biochemical adaptation to the abnormal in utero environment and as a result the addiction of the mother now becomes the psychological addiction of the fetus. The substance exposed baby is NOT actually addicted, instead it is the psychological cravings that lead to substance seeking behaviors.
The baby’s dependence on the substance continues after birth and with the cutting of the cord the baby’s drug supply is abruptly removed. The baby however continues to metabolize and excrete the substance and when low tissue levels have been reached withdrawl signs occur. Since the drug is no longer available the baby’s central nervous system becomes overstimulated causing the symptoms of withdrawl.
There are two theories on neonatal withdrawl
1. Disuse hypersensitivity theory where the nervous system responds to the depressant drug
by increasing the sensitivity of the target receptors in the brain. The removal of the drug
causes the target receptors to become overwhelmed by input that was previously blocked
by the drug.
2. Neural hyperactivity theory occurs when normal minor activity pathways become more
active when the depressant drug blocks the usual neural pathway. When the depressant
drug is removed, both pathways are active resulting in neural hyperactivity.
Withdrawl symptoms occur from a few hours up to 2 weeks of age. The timing of the withdrawl onset depends on the time of the last drug exposure and the metabolism and excretion of the drug and its metabolites.
The behaviors we see in infants are:
- high pitched cry
- inability to sleep
- frantic sucking of fists
- nasal stuffiness
- poor feeding behaviors
- regurgitation, vomiting and losse stools
- hyperactive moro reflex
What can we do?
- swaddling (deep pressure touch)
- soft pack baby carrier
- smooth slow rocking
- decrease feeding intervals
- reduce environmental stimuli
- lambskin bedding
Although no actual studies have been found to date identifying long term changes to the receptor sites within the nervous system, many therapists report long term sensory processing challenges and arousal issues in this population. What have you observed?