Functional Neuroimaging in the Examination of Effects of Prenatal Alcohol Exposure

Abstract

Functional neuroimaging offers the opportunity to understand the effect of prenatal alcohol exposure on the activities of the brain as well as providing a window into the relationship between neural activation and the behavioral outcomes that have been described in affected individuals. Several different methodologies have been used to examine the neurophysiological signal changes associated with different brain functions in prenatally exposed individuals and those diagnosed with fetal alcohol syndrome (FAS) or other fetal alcohol spectrum disorders (FASD). These include electroencephalography (EEG), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI). These studies demonstrate that it is feasible to use these technologies with this clinical population and that the damage to the central nervous system associated with prenatal alcohol exposure has widespread functional implications; however, currently, the literature in these areas is limited and unsystematic. Functional MRI with this clinical population has just begun to explore the implications of prenatal alcohol exposure with the first paper published in 2005. Other methodologies are similarly limited in scope. Nonetheless, these functional neuroimaging studies suggest that prenatal alcohol exposure, or a diagnosis of FAS, may lead to restrictions in neural efficiency or a global decrement in processing resources.

Cerebral Magnetic Resonance Imaging in Children With Prenatal Drug Exposure

“…13,98 Reduction of the overall brain size has been the most consistent finding in children with FASD. 13 Several macrostructural abnormalities, like malformations of the corpus callosum and cerebellar atrophy, have been reported in prenatally alcohol-exposed children.…”

A Bio-Social and Ethical Framework for Understanding Fetal Alcohol Spectrum Disorders

“…While this approach is purportedly less subject to confounding than traditional epidemiological methods, the validity of these inferences still depends on the reliability and validity of self-reported alcohol consumption during pregnancy. Neuroimaging studies have explored the effects of alcohol on neurodevelopment [6,9]. These studies often compare in utero alcohol-exposed persons with 'normal' controls who have had no or low in utero alcohol exposure [9].…”

“…Neuroimaging studies have explored the effects of alcohol on neurodevelopment [6,9]. These studies often compare in utero alcohol-exposed persons with 'normal' controls who have had no or low in utero alcohol exposure [9]. However, there are a number of issues that may affect the validity of these studies: 1) the way in which 'normal' and 'exposed' cases are identified may be subject to a number of systematic biases; 2) studies to date have not followed up subjects over time and, therefore, it is unclear whether observed differences between cases and controls persist, or tend to the population norm, over time; 3) neuroimaging studies can only identify brain differences associated with cognitive deficits between cases and controls; they cannot determine whether prenatal alcohol exposure is the cause of the difference; and finally 4) prenatal alcohol exposure can produce microcephaly, where a significantly smaller brain develops compared with that of non-alcohol exposed individuals.…”

“…However, neuroimaging requires the projection of images onto a standardized brain template. The difference in size between an alcohol affected brain and that of a 'normal' brain may cause skewed projections [9].…”

“…In these latter conditions, the facial deformities that characterise FAS may be absent. Advances in epidemiology, biogenetics and neurobiology are changing how FASD is understood [2,[6][7][8][9] but there are as yet no biomarkers or definitive diagnostic tests for FASD. A diagnosis of FASD is conferred on the basis of clinical judgement according to a number of different diagnostic criteria, and there is some debate as to the validity of different approaches to its diagnosis [10].…”