Neurological alterations in fetal alcohol spectrum syndrome
The role of ethanol as a teratogenic agent has been widely recognized for decades; it is considered the main identifiable and preventable cause of cognitive deficits and congenital malformations that directly involve the central nervous system.
Prenatal alcohol exposure can lead to a group of conditions collectively known as fetal alcohol spectrum disorders (FASDs). This umbrella term conceptually encompasses a wide range of physical, mental, behavioral, and cognitive impairments resulting from damage to the central nervous system caused by alcohol exposure during intrauterine life.
Diagnosing FASD requires knowledge, expertise, a thorough pediatric and neurological evaluation, and a multidisciplinary approach; therefore, it must be carried out by a team of professionals with training and experience in this field.
Clinical features of fetal alcohol spectrum disorders
Although fetal alcohol spectrum disorders are lifelong and there is no cure as such, it is of fundamental importance to be able to identify children who suffer from it early, in order to help them improve their abilities and reach their full potential.
| Key concepts to take home |
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FASDs only occur when a pregnant woman consumes alcoholic beverages during pregnancy, so it is a completely preventable disorder. |
| Alcohol concentrates in the blood of the developing baby in higher quantities than in the mother, since the fetus metabolizes alcohol much more slowly than the adult. |
It can cause damage not only to the central nervous system, but also to other organs, so there is currently no amount of alcohol that is considered safe during pregnancy. |
It should be noted that the problems arising from this disorder are irreversible and the symptoms vary greatly from person to person. |
Alcohol-related neurodevelopmental disorders
The fact that alcohol ingested by the mother easily passes through the placenta, that the fetus does not have the mature mechanisms to metabolize and eliminate it (consequently increasing the exposure time of the nervous system to this teratogen), and that during pregnancy (especially in the first trimester), brain structures are forming and developing; means that irreversible damage can occur during these crucial periods of nervous system development.
As we have previously discussed, children with FASD may present with a range of brain abnormalities that lead to problems in academic performance and daily living activities. However, there is no single pathognomonic behavioral profile or cognitive-behavioral pattern that manifests in all individuals in the same way; the damage caused by alcohol consumption during pregnancy can be modulated by multiple factors, both genetic and environmental.
While in some cases the clinical expression can be severe, in others not all symptoms may be present, or they may be much milder (to the point of not being recognized as a direct consequence of alcohol consumption during the embryonic stage). Therefore, no two children with FASD are alike, and each case must be analyzed individually.
However, thanks to advances in neuroimaging techniques, structural and volumetric abnormalities have been identified from a neurological point of view in several regions of the brain; these include the basal ganglia, the cerebellum (especially in the vermis), the hippocampus and the corpus callosum (total or partial agenesis).
Psychiatric manifestations of fetal alcohol spectrum disorders
The important role these brain areas play in human cognitive and behavioral performance would partly explain the neuropsychological dysfunction profile present in these patients. For example, alterations in the basal ganglia and their connections to the frontal lobe would be implicated in the executive control difficulties and ADHD-like behaviors experienced by many of these individuals, and hippocampal involvement would be directly related to impairments in certain memory functions. Similarly, cerebellar involvement (a structure involved in balance, coordination, and learning) would underlie the difficulties these children demonstrate in these particular areas.
The deleterious effects of alcohol on neuronal migration processes that begin in the early stages of pregnancy have also been widely documented (and which can cause malformations of cortical development and in some cases epilepsy).
The implications of all these anatomical alterations therefore have a functional impact; and clinically they manifest themselves through a variable cognitive-behavioral functioning profile depending on the individual characteristics of each particular case.
For example, while many of these children may have a normal IQ, it is known that they are more likely to have lower average cognitive functioning compared to their healthy peers (since they do not reach their full intellectual potential, for which they are genetically predisposed). Or, at the most severe end of the spectrum, they may present varying degrees of intellectual disability (generally moderate, with a variable IQ score between 50 and 80).
However, as we have previously described, from a neuropsychological point of view other domains may also be affected (regardless of overall intellectual performance); such as executive function (organizational ability, self-management, planning), attention, learning, memory, language, visuospatial ability and motor function (motor coordination).
Main deficits presented by TEAF |
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Deficit in executive functioning:
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Visuospatial impairments, motor coordination problems, balance issues, and dexterity problems. |
Learning difficulties, working memory impairments, language impairments, or difficulties in specific areas such as mathematics. |
Children with FASD may exhibit ADHD symptoms, including hyperactivity, inattention, and impulsivity. They are generally very active children with significant attention deficits, poor reflective capacity, and impulsivity. |
Some cases present difficulties in social skills with their peers, or conflictive socialization. In addition, they sometimes exhibit emotional lability, behavioral disorders, irritability, and associated psychiatric comorbidity. |
There may be atypical behaviors (flapping, rocking, screaming, unproductive repetitive movements such as smelling certain things, hair pulling, without apparent purpose). |
Furthermore, these children may exhibit behavioral problems with ADHD symptoms, adaptive dysfunction, emotional lability, and psychiatric disorders. This type of functioning can consequently generate significant problems in family, school, and social adjustment.
In summary, there are two functional areas that are interrelated and may be affected in this particular population: the neurocognitive area and the behavioral area.
The intrauterine damage caused by prenatal alcohol exposure is irreversible. Various brain areas involved in fundamental cognitive, behavioral, and emotional control can be affected. However, early diagnosis, monitoring, and treatment prevent the development of complications or secondary disorders and improve the medium- and long-term prognosis.
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