Alcohol abuse has long been a major problem affecting more than 300 million people worldwide each year [1]. Alcoholism is a major risk factor for mortality and disability in young adults [2]. Yet, the continued use of this detrimental substance is shockingly prevalent. The lack of awareness and prevention may eventually lead to irreversible damage [2]. Statistics from a UK study in 2012 found that alcohol killed 3,300,000 people as a result of 1 death every 10 seconds [2]. Evidence from several animal studies have portrayed the negative effects of ethanol on the developing brain of neonatal mice (Fig. 1). Consumption of alcohol during pregnancy carries over to the baby through the umbilical cord [3]. Ethanol abuse in the perinatal period can lead to miscarriage, stillbirth, or a wide range of lasting disabilities [3].

Years of research on mice genetics has allowed scientists to explore the neurological effects of ethanol. Exposure to ethanol in the perinatal period has been proved to have deleterious effects on the developing brain, resulting in cognitive and behavioral deficits [5]. Adverse effects were tested in rats by administration of 5.25 g/kg/day of alcohol in postnatal days 23-24 [6]. The brain region that was found to be most affected by the prolonged exposure of ethanol is the central nervous system (CNS). CNS is a crucial brain system that controls behavior, learning, memory, and attention [5]. These defects in the CNS due to fetal exposure to alcohol are collectively described as fetal alcohol spectrum disorders (FASD). The changes shown in the underdeveloped brain of a rat include hyperactivity, difficulty in learning, as well as reduced volume in several brain regions [5]. Drinking during gestation has shown impairment in behavior, and specifically in the tasks regulated by the hippocampal function [5]. Proper functioning of the hippocampus is crucial because this brain region plays a significant role in learning and memory (Fig. 2) [5].

Studies show individuals with FASD have difficulty in the regulation of emotional arousal resulting in increased susceptibility to mental health disorders [7]. The emphasis of the study is on drug development for FASD motivated by the high cases of hyperactivity observed in rodent models [5]. While comparing similar studies, it was concluded that ethanol exposure has adverse effects in the third-trimester of the mouse model [5]. In another study, Green and colleagues noticed a drastic reduction in purkinje cells of the cerebellum in rats [6]. Purkinje cells are neurons that are located in the cerebellar cortex [8]. They appear to have large, branched dendritic trees which are responsible for combining vast amounts of information in the brain (Figure 3).. The main role of these cells is to manage functions, such as movement, cognition, and emotion [8]. The evidence pertaining to reduction in purkinje cells further supports the hypothesis that prolonged exposure to ethanol leads to impairment in behavioral tasks in neonates. Additionally, Magnetic Resonance Imaging (MRI) of the subjects showed an overall decrease in brain size, abnormalities in the basal ganglia, cerebellum, and corpus callosum [6].

Researchers have gained a better understanding of potential treatment options using animal models. Advanced research of FASD allows scientists to manage the precise timing of the two most crucial determinants of the neurotoxic effects on the developing brain. These two determinants are ethanol exposure and blood alcohol concentration. Studies have found the most significant period during which the brain is affected by alcohol-induced neurotoxic effects to be during the first week of the neonate [6]. As a result, slower response time was recorded in neonatal rats in their first week [6]. There is a possibility that the damage caused in certain brain regions due to prolonged ethanol exposure may be irreversible, however further research is required to make definite conclusions. Nevertheless, there is no safe amount of alcohol that can be acquired during pregnancy without detrimental effects in neonates [3]. Thus, it is crucial to have a balanced diet and a healthy lifestyle especially in the perinatal stage to prevent adverse effects in neonates.

References

1. Alcohol. Who.int. (2021). Retrieved from https://www.who.int/news-room/fact-sheets/detail/alcohol.
2. Shah, D. (2017). Awakening to the alcohol epidemic – need of the hour. Indian Journal Of Public Health, 61(3), 205. https://doi.org/10.4103/ijph.ijph_226_16
3. Alcohol Use in Pregnancy. Centers for Disease Control and Prevention. (2021). Retrieved from https://www.cdc.gov/ncbddd/fasd/alcohol-use.html.
4. Your Brain’s Memory Storage Command Center — The Behavior Hub. The Behavior Hub. (2021). Retrieved 18 November 2021, from https://www.thebehaviorhub.com/blog/2020/11/10/the-hippocampus.
5. Xu, W., Hawkey, A. B., Li, H., Dai, L. Brim, H. H., Frank, J. A., Luo, F. J., Barron, S., and Chen, G. (2018). Neonatal Ethanol Exposure Causes Behavioral Deficits in Young Mice. Alcoholism: Clinical & Experimental Research, 42(4), 743-750. https://doi.org/10.1111/acer.13598
6. Green, J. T., Rogers, R. F., Goodlett, C. R., and Steinmetz, J. E. (2006). Impairment in eyeblink classical conditioning in adult rats exposed to ethanol as neonates. Alcoholism: Clinical and Experimental research, 24(4), 438-447. https://doi-org.subzero.lib.uoguelph.ca/10.1111/j.1530-0277.2000.tb02010.x
7. Temple, V. K., Cook, J. L., Unsworth,K., Rajani, H., and Mela, M. (2019). Mental Health and Affect Regulation Impairment in Fetal Alcohol Spectrum Disorder (FASD): Results from the Canadian National FASD Database, Alcohol and Alcoholism, 54(5), 545–550. https://doi.org/10.1093/alcalc/agz049
8. Paul, M. S., and Limaiem F. (2021). Histology, Purkinje Cells. Treasure Island (FL): StatPearls Publishing; Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK545154/
9. Purkinje Cell 2.0. (2021). Neuroscience from Technology Networks. Retrieved from https://www.technologynetworks.com/neuroscience/news/virtual-cerebellar-purkinje-cell-gets-an-upgrade-307326.