Cognitive outcomes in prenatal methamphetamine exposed children aged six to seven years.

BACKGROUND: Methamphetamine use among pregnant women has become a significant problem. Research delineating the cognitive outcomes of prenatal methamphetamine exposure (PME) in early childhood is limited, however. The aim of this study was to examine effects of PME on cognition in six-to-seven-year-old children. METHODS: PME children (n=23) and unexposed controls (n=22) completed a battery of neurocognitive tests, which included the Kaufman Assessment Battery for Children, Boston Naming Test, Beery Developmental Test of Visual-Motor Integration, and Grooved Pegboard Test. RESULTS: Independent samples t-tests revealed that PME children scored significantly worse than controls on the measures of IQ, learning and memory, confrontation naming, visual-motor integration, and fine motor coordination. Hierarchical regression analyses that included potential confounding sociodemographic, co-exposure and anthropometric variables confirmed that PME impacts negatively on cognitive performance. CONCLUSIONS: The study confirms that PME has deleterious effects on cognition in several broad cognitive domains, likely by altering underlying brain circuitry in development. These effects may be particularly pronounced at the time when children enter formal schooling. Extended follow-ups into late childhood might help elucidate the developmental trajectory of cognitive dysfunction in PME, and subsequent effects on everyday functioning.

White matter integrity and cognitive performance in children with prenatal methamphetamine exposure.

There is emerging evidence on the harmful effects of prenatal methamphetamine (MA) exposure on the structure and function of the developing brain. However, few studies have assessed white matter structural integrity in the presence of prenatal MA exposure, and results are inconsistent. This investigation thus used diffusion tensor imaging (DTI) to investigate white matter microstructure and cognitive performance in a group of prenatal MA exposed (or MA) children and controls of similar age. Seventeen MA children and 15 healthy controls (aged 6-7 years) underwent DTI and assessment of motor function and general cognitive ability. Whole brain analyses of white matter structure were performed using FSL's tract-based spatial statistics comparing fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD). Mean diffusion values were extracted from white matter regions shown to differ across groups to determine whether variations in FA predicted cognitive performance. Analyses were controlled for maternal nicotine use. MA children showed significantly lower FA as well as higher MD, RD and AD in tracts that traverse striatal, limbic and frontal regions. Abnormal FA levels in MA children were significantly associated with poorer motor coordination and general cognitive ability sub-items that relate to aspects of executive function. Our findings suggest that, consistent with previous studies in older children, there are disruptions of white matter microstructural integrity in striatal, limbic and frontal regions of young MA exposed children, with prominent cognitive implications. Future longitudinal studies may clarify how prenatal MA exposure affects white matter structural connectivity at different stages of brain maturation.

Effects of prenatal methamphetamine exposure: a review of cognitive and neuroimaging studies.

Prenatal methamphetamine exposure (PME) is a significant problem in several parts of the world and poses important health risks for the developing fetus. Research on the short- and long-term outcomes of PME is scarce, however. Here, we summarize present knowledge on the cognitive and behavioral outcomes of PME, based on a review of the neuroimaging, neuropsychology, and neuroscience literature published in the past 15 years. Several studies have reported that the behavioral and cognitive sequelae of PME include broad deficits in the domains of attention, memory, and visual-motor integration. Knowledge regarding brain-behavior relationships is poor, however, in large part because imaging studies are rare. Hence, the effects of PME on developing neurocircuitry and brain architecture remain speculative, and are largely deductive. Some studies have implicated the dopamine-rich fronto-striatal pathways; however, cognitive deficits (e.g., impaired visual-motor integration) that should be associated with damage to those pathways are not manifested consistently across studies. We conclude by discussing challenges endemic to research on prenatal drug exposure, and argue that they may account for some of the inconsistencies in the extant research on PME. Studies confirming predicted brain-behavior relationships in PME, and exploring possible mechanisms underlying those relationships, are needed if neuroscience is to address the urgency of this growing public health problem.