Opioid dependence is a serious public health issue associated with significant morbidity and mortality. Over the past few years the amount of opioid users receiving opioid maintenance treatment (OMT) has increased significantly in Norway. As a result, an increasing number of children are being prenatally exposed to long-lasting opioids such as methadone or buprenorphine. While OMT is generally recommended for pregnant opioid-dependent women, few studies have investigated the long-term development of children of women in OMT.
The overall aim of the thesis was to investigate whether children of women in OMT who have been prenatally exposed to methadone or buprenorphine are at an increased risk of developing neurocognitive and psychomotor impairments. Participating in this study was a national cohort of children born to women in OMT during the period January 2005-March 2007 (N=35) and a comparison group (N=32) of non-exposed children, all four-years-old at the time of the study. In order to measure cognitive and psychomotor functioning, several methods were used including standardized cognitive tests, eye tracking, and questionnaires.
The first paper investigated the functioning of the mirror neuron system (MNS), a complex neural circuit involved in learning and social interactions. Since MNS functioning cannot be directly measured without using invasive techniques, it was measured indirectly by measuring children’s ability to predict another person’s action goals by means of their eye movements. Results revealed that children of women in OMT made fewer proactive goal-directed eye movements than children in the comparison group, which could potentially affect their learning and social skills.
The second paper examined executive function (EF), which can be characterized as a group of higher cognitive processes responsible for purposeful, goal-directed, problem-solving behavior. EF was measured with a battery of neuropsychological tests as well as a questionnaire (BRIEF-P) filled out by the child’s parent. Children of women in OMT scored significantly lower than the comparison group on all administered tasks of EF and experienced more EF problems in everyday activities.
The third paper measured visual selective attention, the ability to direct visual attention away from irrelevant sources and towards relevant sources of information, using a spatial negative priming (SNP) paradigm. Results revealed that prenatally exposed children had a smaller SNP effect, longer saccade latencies, and more attention problems. In addition, it was found that
NAS and marijuana exposure significantly predicted saccade latency. These results are noteworthy as deficits in visual selective attention may negatively affect recognition, goal-directed behavior, memory, and perceptual awareness, which are crucial for learning.
Together, the three studies presented in the dissertation demonstrate that children of women in OMT are at an increased risk of experiencing difficulties in neurocognitive functioning. Children of women in OMT should therefore be closely monitored, not only at birth and during the neonatal period, but also throughout childhood.