Recent studies have documented the effects of ethanol on miRNAs and the role miRNAs play to mediate ethanol’s teratogenic effects on a developing fetus. By repressing these miRNAs, ethanol induces the expression of the miRNAs’ target mRNAs, which is expected to result in increased translation of proteins, like Jag1 and ELAVL2/HuB in this case. Jag1 promotes the rapid proliferation of NSCs to establish a neuronal identity while ELAVL2/HuB promotes neuronal differentiation 61,62. These data suggest that suppression of these ethanol-sensitive miRNAs may promote premature neuronal differentiation and deplete NSC/NPC population.
The increasing rate of child-bearing-aged women who consume alcohol can be considered to increase the chance of alcohol exposure during pregnancy, whether intentionally or unintentionally. FASD is a range of conditions in the child caused by the mother drinking alcohol during pregnancy. Prenatal alcohol exposure is a leading preventable cause of birth defects and neurodevelopmental disorders in the United States. Women who need help to stop drinking alcohol can talk to their health care provider about treatment options.
What Are the Types of Fetal Alcohol Spectrum Disorders?
Dysregulation is evident at multiple levels of the axis, and appears to reflect changes in both HPA drive and feedback regulation and/or in the balance between drive and feedback. This may be protective for ethanol-exposed animals, minimising enhanced basal pituitary activity in the face of enhanced hypothalamic drive. Finally, the sexually dimorphic effects of PAE suggest a role for the gonadal steroids or possibly an alteration in gonadal–adrenal interactions in mediating the effects of ethanol on HPA activity and regulation.
Prenatal ethanol exposure reprogrammes foetal HPA function
These studies add to the cohort of studies that demonstrate the behavioral and anatomical consequences of miRNA dysregulation. The AAP recommends initial assessment and diagnosis by the child’s pediatrician.12 Referrals for additional evaluation and treatment can be made to other clinicians and health care professionals or, when available, to a specialized multidisciplinary team for a comprehensive evaluation and care. To determine the effects of prenatal exposure on child development, factors such as the timing, dose, and pattern of alcohol exposure must be considered, because growth, morphologic abnormalities, and CNS deficits occur at different points during gestation.
Socioemotional Function
The inconsistencies in human studies have various potential causes and highlight the complicated nature of PAE pathogenesis and pubertal onset. Varied results in human studies could be potentially explained by looking at confounding environmental factors, such as nutrition, socioeconomic standing, and level of stress during pregnancy and during childhood. For example, one study showed prenatal alcohol exposure that mothers who had children diagnosed with FASDs had a lower intake of several nutrients, such as calcium, which is important for bone development, and riboflavin, which plays an important role in vital biochemical reactions 110. This lack of nutrients during the prenatal period also has the potential to affect pubertal onset and a person’s health throughout their life. The effects of PAE are multifactorial and more research is needed to elucidate the effects of PAE so interventions can be made to attenuate debilitating consequences. Even if PAE does not directly affect the onset of puberty, the effect of PAE on the HPG axis is still vital to understand since the reproductive system is intimately connected with the HPG axis.
Summary of HPA changes
CNS abnormalities include microcephaly, tremors, hyperactivity, lack of motor skills, deficits in attention, learning difficulties, intellectual or cognitive impairment, and seizures 12. Facial abnormalities include short palpebral fissures, epicanthal folds, flat midface, hypoplastic philtrum, and a thin upper vermilion border (Fig. 1) 12,13. However, it is often missed or misdiagnosed, preventing affected children from receiving the required services promptly 15. Importantly, gonadectomy unmasked differential HPG influences on HPA activity, as well as differential responsiveness of central components of the HPG axis to androgens in PAE compared to control males.
- If you used any amount of alcohol while you were pregnant, talk with your child’s healthcare provider as soon as possible and share your concerns.
- As a toxicant, alcohol can lead to a variety of physical and neurological anomalies in the fetus that can lead to behavioral and other impairments which may last a lifetime.
- Oestradiol facilitates ACTH release during stress, whereas progesterone inhibits the facilitatory effects of oestradiol (111).
- This misclassification can increase type II error (i.e., false negatives) by increasing risk outcomes in the group considered to have no prenatal alcohol exposure, making it less likely that effects that truly are present will be identified.
- Consequently, attributing poor birth outcomes to pregnancy alcohol consumption is a complicated and ongoing task that requires continued attention to validated methodology and to identifying specific biological mechanisms.
Functional neurodevelopment outcomes
Recent studies have focused on identifying mechanisms that mediate the immediate teratogenic effects of alcohol on fetal development and mechanisms that facilitate the persistent toxic effects of alcohol on health and predisposition to disease later in life. This review focuses on the contribution of epigenetic modifications and intercellular transporters like extracellular vesicles to the toxicity of PAE and to immediate and long-term consequences on an individual’s health and risk of disease. In summary, cases of FAS are characterized by abnormalities in growth, morphology, and CNS development.
The current review revealed a lack of evidence for the utility of neurological or clinically available MRI assessments to determine effects of PAE. Whilst there is variability in how structural brain abnormalities, seizures of unknown origin, hearing and vision impairment, and other neurological conditions are considered, current FASD diagnostic criteria include many of these outcomes. However, we suggest that brain abnormalities and neurological conditions be considered in the assessment process to inform individual support planning and future research to better understand potential associations with PAE. The evidence linking prenatal alcohol exposure to deficits in socioemotional function is based on data from multiple sources, including ratings by parents and teachers and self-reports obtained from adolescents. However, there have been few direct observational studies to identify which specific aspects of socioemotional function are impaired (e.g., empathy, recognition of emotional expression, moral reasoning). It is particularly instructive to consider studies comparing children with FAS with children not exposed to alcohol who have similar low IQ scores.
Fetal Alcohol Spectrum Disorders (FASDs)
Importantly, we show that, although alterations in HPA responsiveness and regulation are robust phenomena, occurring in both male and female offspring, sexually dimorphic effects of ethanol are frequently observed. Studies investigating the mechanisms underlying differential effects of ethanol on male and female offspring are discussed, with special emphasis on altered modulatory influences of the hypothalamic-pituitary-gonadal (HPG) hormones and serotonin on offspring HPA function. Finally, possible mechanisms underlying foetal programming of the HPA axis, and the long-term implications of increased exposure to endogenous glucocorticoids for offspring vulnerability to illnesses or disorders later in life, are discussed. This review is based, in part, on previously published reviews (14, 15), and on published and ongoing studies. However, this review presents both a new perspective and new data on sex differences following PAE, and their potential implications for later life outcomes.
There is no known safe amount of alcohol use during your pregnancy or when you are trying to get pregnant. Both environmental factors and genetic factors have been shown to influence the HPG axis and therefore the onset of puberty (created with BioRender.com; accessed on 7 July 2021). The criteria used in this study corresponded to the criteria for alcohol abuse and dependence listed in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. In general, the terms “alcoholic” and “alcoholism,” as used in this article, encompass both diagnoses.
- All authors have had full access to all data in the study and had final responsibility for the decision to submit for publication.
- Animal studies, tightly controlled human studies, and studies that have examined structural and chemical alterations would suggest, at least in part, a direct physiological mechanism.
- Furthermore, PAE females but not males exhibit blunted ACTH responses to 8-OH-DPAT, but increased ACTH responses to DOI compared to controls, suggesting an altered interaction between the HPA axis and the 5-HT system in PAE animals (182).
- Microvesicles, on the contrary, are produced through outward budding of the plasma membrane, while apoptotic bodies result from cell fragmentation during programmed cell death 81.
- Finally, PAE animals exhibit altered neurotransmitter regulation of HPA activity, particularly in the serotonergic system (55, 182, 215, 216), suggesting altered serotonergic influences on HPA activity similar to those seen in depression.
Links to NCBI Databases
Fetal alcohol syndrome is a condition in a child that results from alcohol exposure during the mother’s pregnancy. Drinking alcohol during pregnancy can cause the child to have disabilities related to behavior, learning and thinking, and physical development. Fetal alcohol spectrum disorders (FASDs) are a group of conditions that can occur in a person exposed to alcohol before birth. People with FASDs can have lifelong effects, including problems with behavior and learning as well as physical problems.
In the brain, kisspeptin neurones are most numerous in the arcuate nucleus (ARC), and two major populations are also found in the periventricular and anteroventral periventricular (AVPV) nuclei (163, 164). Interestingly, there are sex differences in the expression of kisspeptin in the AVPV, with female rats having a 10-fold greater KISS-1 expression than males (165). One way to gauge CNS functioning is to use neuropsychological measures designed to assess brain functioning. Using such measures, Mattson and colleagues (1996a) found that 5- to 16-year-old children with FAS had significant verbal learning and memory deficits. Similarly, Kodituwakku and colleagues (1995) reported memory deficits in 13-year-old children with FAS, and Coles and colleagues (1997) found that children with FAS had deficits in problem-solving, information processing and storage, and visual and spatial skills. Overall, evidence from this systematic review provides direction regarding which components should currently be considered for inclusion in diagnostic criteria for FASD.
There was a lack of evidence from studies examining PAE to support inclusion of non-sentinel dysmorphic features, social cognition, speech-sound impairments, neurological conditions, seizures, sensory processing or structural brain abnormalities (via clinical MRI) in diagnostic criteria. In view of the above findings, we examined the modulatory effects of the gonadal hormones and the 5-HT system on HPA regulation in adult PAE females tested across the oestrous cycle under basal conditions (183). We hypothesised that an MR/GR imbalance may underlie the HPA hyper-responsiveness observed in PAE females, manifested differentially as a function of the oestrous cycle. Our data demonstrate, for the first time, long-lasting consequences of prenatal ethanol exposure on basal levels of hippocampal MR, GR and 5-HT1A mRNA as a function of oestrous cycle stage, supporting a role for the gonadal hormones in mediating these effects. In addition, 5-HT1A receptor mRNA levels were increased in PAE compared to PF and control females in dioestrous (Table 1).
Interestingly, removal of circulating ovarian steroids prior to puberty attenuated the differences in ACTH released by PAE and control females. The authors concluded that these findings suggest the presence of a functional relationship between the pathways influenced by prenatal ethanol and those influenced by female sex steroids, both of which are important in regulating HPA activity. Although the hypothalamus appears to represent a major site of prenatal ethanol effects (85), some studies suggest a possible role for the pituitary in mediating effects of PAE on HPA activity, and similar to studies on the hypothalamus, indicate a marked sexual dimorphism in the effects of PAE. For example, studies report increased pituitary pro-opiomelanocortin (POMC) mRNA in PAE males but not females (88), and a reversal of this effect by maternal adrenalectomy.