GABAa receptor density alterations revealed in a mouse model of early moderate prenatal ethanol exposure using [18F]AH114726

Recent breakthroughs in understanding the cerebellum's role in fetal alcohol spectrum disorder: A systematic review

Exposure to alcohol during fetal development can lead to structural and functional abnormalities in the cerebellum, a brain region responsible for motor coordination, balance, and specific cognitive functions. In this systematic review, we comprehensively analyze a vast body of research conducted on vertebrate animals and humans over the past 13 years. We identified studies through PubMed and screened them following PRISMA guidelines. Data extraction and quality analysis were conducted using Covidence systematic review software. A total of 108 studies met our inclusion criteria, with the majority (79 studies) involving vertebrate animal models and 29 studies focusing on human subjects. Animal models included zebrafish, mice, rats, sheep, and non-human primates, investigating the impact of ethanol on cerebellar structure, gene/protein expression, physiology, and cerebellar-dependent behaviors. Additionally, some animal studies explored potential therapeutic interventions against ethanol-induced cerebellar damage. The human studies predominantly adopted cohort designs, exploring the effects of prenatal alcohol exposure on cerebellar structure and function. Certain human studies delved into innovative cerebellar-based diagnostic approaches for fetal alcohol spectrum disorder (FASD). The collective findings from these studies clearly indicate that the cerebellum is involved in various neurophysiological deficits associated with FASD, emphasizing the importance of evaluating both cerebellar structure and function in the diagnostic process for this condition. Moreover, this review sheds light into potential therapeutic strategies that can mitigate prenatal alcohol exposure-induced cerebellar damage.

High-resolution diffusion tensor imaging identifies hippocampal volume loss without diffusion changes in individuals with prenatal alcohol exposure

BACKGROUND

Magnetic resonance imaging (MRI) studies of prenatal alcohol exposure (PAE) commonly report reduced hippocampal volumes, which animal models suggest may result from microstructural changes that include cell loss and altered myelination. Diffusion tensor imaging (DTI) is sensitive to microstructural changes but has not yet been used to study the hippocampus in PAE.

METHODS

Thirty-six healthy controls (19 females; 8 to 24 years) and 19 participants with PAE (8 females; 8 to 23 years) underwent high-resolution (1 mm isotropic) DTI, anatomical T1-weighted imaging, and cognitive testing. Whole-hippocampus, head, body, and tail subregions were manually segmented to yield DTI metrics (mean, axial, and radial diffusivities-MD, AD, and RD; fractional anisotropy-FA), volumes, and qualitative assessments of hippocampal morphology and digitations. Automated segmentation of T1-weighted images was used to corroborate manual whole-hippocampus volumes.

RESULTS

Gross morphology and digitation counts were similar in both groups. Whole-hippocampus volumes were 18% smaller in the PAE than the control group on manually traced diffusion images, but automated T1-weighted image segmentations were not significantly different. Subregion segmentation on DTI revealed reduced volumes of the body and tail, but not the head. There were no significant differences in diffusion metrics between groups for any hippocampal region. Correlations between age and volume were not significant in either group, whereas negative correlations between age and whole-hippocampus MD/AD/RD, and head/body (but not tail) MD/AD/RD were significant in both groups. There were no significant effects of sex, group by age, or group by sex for any hippocampal metric. In controls, seven positive linear correlations were found between hippocampal volume and cognition; five of these were left lateralized and included episodic and working memory, and two were right lateralized and included working memory and processing speed. In PAE, left tail MD positively correlated with executive functioning, and right head MD negatively correlated with episodic memory.

CONCLUSIONS

Reductions of hippocampal volumes and altered relationships with memory suggest disrupted hippocampal development in PAE.