Comparison of spatial working memory in children with prenatal alcohol exposure and those diagnosed with ADHD; A functional magnetic resonance imaging study

Abstract

BackgroundAlcohol related neurodevelopmental disorder (ARND) falls under the umbrella of fetal alcohol spectrum disorder (FASD), but individuals do not demonstrate the facial characteristics associated with fetal alcohol syndrome (FAS), making diagnosis difficult. While attentional problems in ARND are similar to those found in attention-deficit/hyperactivity disorder (ADHD), the underlying impairment in attention pathways may be different.MethodsFunctional magnetic resonance imaging (fMRI) of a working memory (1-back) task of 63 children, 10 to 14 years old, diagnosed with ARND and ADHD, as well as typically developing (TD) controls, was conducted at 3 T. Diffusion tensor imaging (DTI) data were also acquired.ResultsActivations were observed in posterior parietal and occipital regions in the TD group and in dorsolateral prefrontal and posterior parietal regions in the ARND group, whereas the ADHD group activated only dorsolateral prefrontal regions, during the working memory component of the task (1-back minus 0-back contrast). The increases in frontal and parietal activity were significantly greater in the ARND group compared to the other groups. This increased activity was associated with reduced accuracy and increased response time variability, suggesting that ARND subjects exert greater effort to manage short-term memory load. Significantly greater intra-subject variability, demonstrated by fMRI region-of-interest analysis, in the ADHD and ARND groups compared to the TD group suggests that moment-to-moment lapses in attention contributed to their poorer task performance. Differences in functional activity in ARND subjects with and without a diagnosis of ADHD resulted primarily from reduced activation by the ARND/ADHD + group during the 0-back task. In contrast, children with ADHD alone clearly showed reduced activations during the 1-back task. DTI analysis revealed that the TD group had significantly higher total tract volume and number of fibers than the ARND group. These measures were negatively correlated with errors on the 1-back task, suggesting a link between white matter integrity and task performance.ConclusionsfMRI activations suggest that the similar behavior of children with ARND and ADHD on a spatial working memory task is the result of different cognitive events. The nature of ADHD in children with ARND appears to differ from that of children with ADHD alone.

Radiological studies of fetal alcohol spectrum disorders in humans and animal models: An updated comprehensive review

“…In the 1-back task, children with ARND showed broader activation of cortical regions compared to healthy children, which was correlated with decreased accuracy and increased response time variability, indicating increased effort to compensate for cognitive deficiency [103]. Despite similar task performance to children with ARND, children with ADHD showed weak activation of the same network, suggesting that children with ADHD relied on different brain regions compared to children with ARND [103].…”

“…Attention deficit hyperactivity disorder (ADHD) is present in many cases of FASD and was suggested as a core deficit in FASD [100;101]. However, the impairments in adaptive function or cognitive ability in individuals with ADHD and FASD appeared distinct in certain respects [102][103][104].…”

Review of Current Neuroimaging Studies of the Effects of Prenatal Drug Exposure: Brain Structure and Function

“…When examined in relation to family history of alcohol use disorders, prenatal alcohol exposure independently predicted increased activation in left middle and superior frontal brain regions [137]. In a direct comparison of adolescents with prenatal alcohol exposure or ADHD, behavioral profiles were similar but the two groups showed differences in how cortical brain regions were recruited for spatial working memory [138]. Overall, prenatal alcohol exposure was associated with an increased effort to compensate in relation to increasing task demands compared to the ADHD group.…”

Cerebral Magnetic Resonance Imaging in Children With Prenatal Drug Exposure

“…143 Image processing and analysis using the SPM12 software package (or earlier versions) has been widely used in previous pediatric samples. 127,[144][145][146] Typical whole brain fMRI analyses using voxel-based methods, like the present study, include more than 50.000 voxels, resulting in numerous statistical tests. Consequently, corrections for multiple comparisons are important in all statistical analyses of fMRI data.…”

“…117,120 The number of prenatally opioid-exposed children included in analyses of BOLD response in paper III (n =11) was also similar to numbers of exposed children included in previous fMRI studies of children with prenatal exposure to alcohol, amphetamines, and tobacco (n = 7-23) reporting group differences in BOLD response during working memory. 145,146,174,175 5.2 Discussion of the results…”