CLINICAL PRESENTATION
What are some of the neurocognitive impairments exhibited by individuals with FASDs?
- Structural Brain Abnormalities
- Among individuals with prenatal alcohol exposure, a wealth of studies have documented structural brain abnormalities (22, 29, 30), including:
- Smaller overall brain volume
- In addition to reductions in brain volume, white matter density appears to be reduced, but gray matter density is increased in certain regions
- The cerebellum has been found to be smaller, and characterized by abnormalities, particularly in the anterior regions of the vermis
- The basal ganglia has been found to be smaller, primarily due to reduced size of the caudate
- The corpus callosum has been found to be smaller, thinning or completely absent (agenesis)
- Agenesis is present in approximately 0.3% and about 2.3% in developmentally disabled populations. Although the true incidence among FAS populations is unknown, it is has been suggested that FAS may be the most common cause of agenesis of the corpus callosum.
- Reduction in size appears specific to the splenium
- In addition to decreased size, abnormalities in shape and location have been documented
- Imaging studies have also documented white matter anomalies in the corpus callosum. A recent study (28) utilizing diffusion tensor and T1-weighted magnetic resonance imaging to examine white matter integrity in children and adolescents with FASDs found that compared to controls, individuals with FASDs exhibited decreased fractional anisotropy in the right lateral temporal lobe and bilaterally in the lateral aspects of the splenium of the corpus callosum.
MRI of a 12-year-old with FAS. The corpus callosum is present, but it is very thin at the posterior section of the brain.
Reprinted with permission from: Mattson & Riley (1995, 31). |
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MRI of a 14 year old with FAS and agenesis of the corpus callosum.
Reprinted with permission from: Mattson, Jernigan, & Riley (1994, 32). |
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Reprinted with permission: Riley et al. (1995, 33).
The two images above are from a 9 year old with FAS. The image on the left is a midsaggital view demonstrating
agenesis of the corpus callosum and the image on the right is 12.5 mm from the midsagittal and shows colpocephaly.
General Intellectual Functioning
- Although FAS is the most common known cause of mental retardation, most children with FASDs do not qualify for a diagnosis of mental retardation.
- The cognitive abilities of individuals affected by prenatal alcohol exposure can vary widely, with studies of this population documenting IQ's ranging from the severe range of mental retardation to the above average range of intellectual functioning.
- In general, however, studies suggest that the majority of alcohol-exposed individuals typically fall below the average range of intellectual functioning (13, 34).
- An important point to note is that many alcohol-affected individuals with normal IQs still exhibit significant deficits in other domains, such as executive or adaptive functioning.
Neurocognitive deficits
- Attentional problems
- Individuals with FASDs commonly present with clinical symptoms consistent with a diagnosis of ADHD.
- Individuals with FASDs are more frequently diagnosed as the inattentive subtype of ADHD as defined by the DSM-IV (35).
- Learning and memory problems
- Prenatal alcohol exposure has been associated with difficulties acquiring new verbal information (36), impairments in both visual and auditory memory (37, 38), and difficulties learning from experience (39, 40)
- Executive functioning
- Individuals with prenatal alcohol exposure show impairments in several aspects of executive functioning including working memory, planning, concept formation, verbal and nonverbal reasoning, cognitive flexibility, and response inhibition (41, 42).
- Speech and language problems
- Individuals with FASDs can often be quite talkative, and may appear to have good language skills at a superficial level. However, when their communication skills are examined at a more meaningful level, impairments in articulation (43), receptive (44) and expressive language (43), semantics, syntax, and pragmatics (45) are evident.
- Visual spatial problems
- Prenatal alcohol exposure has been linked with difficulty understanding and remembering spatial relationships and poor visual perception (46)
- Motor problems
- Motor difficulties include fine and gross motor deficits, impairments in balance, and poor coordination (47-49)
What are some of the signs of prenatal alcohol exposure in infancy, childhood, adolescence, and adulthood?
- FASDs are associated with deficits throughout the life span. However, these deficits are likely to manifest differently during different development periods.
Infancy
- Infants with an FASD may exhibit increased negative affect (50), poor habituation and increased low arousal (51), sleep disturbances (52), less mature motor behavior and increased level of activity (53), poor sucking (54), and feeding difficulties which may present as failure to thrive (55).
Early Childhood
- As children with FASDs enter their preschool years, they may show problems with inattention, hyperactivity, and impulsivity (56), dysregulation, irritability, temper outbursts; difficulty dealing with transitions and adapting to change (55).
Middle Childhood
- Both externalizing (e.g., impulsivity, inattention, etc.) and internalizing (e.g., depressive symptoms) problems have been observed in children with prenatal alcohol exposure during this period (57, 58).
- School problems include increased rates of learning disorders (59), poor grades, and having difficulty completing homework. These children may demonstrate apparent mastery of a skill one day, and then an inability to perform that same skill the following day. Many alcohol-affected children end up in special education (46).
- Social problems include difficulty reading social cues and a tendency to be socially indiscriminant (37,55,60). Their excessive friendliness can be mistakenly viewed as an indicator of good social functioning, and parents may not realize that their children are regarded as intrusive or annoying, and despite being quite friendly, do not seem to have any real friends. Difficulties with understanding cause and effect relationships and recognizing the impact of consequences of their behavior can cause significant problems for these individuals, particularly in social interactions (55)
Adolescence
- Many alcohol-affected adolescents engage in risky behaviors.
- School problems, including suspension, expulsion, and dropping out, are a major concern (13).
- Increased rates of delinquency have been found among adolescents with prenatal alcohol exposure in comparison to non-exposed adolescents (61). Notably, individuals with ARND were found to be at greater risk for delinquency than individuals who met the full criteria for FAS, perhaps because the former group was less readily identified as in need of services.
- Difficulties with maintaining appropriate physical boundaries and navigating peer and romantic relationships may become particularly salient among adolescents with FASDs. Streissguth et al. (13) found that that 58% of adolescents with FAS or FAE had trouble getting along with peers, 48% had engaged in inappropriate sexual behavior, most commonly promiscuity and inappropriate sexual advances.
- Individuals with FASDs may be especially vulnerable to experimentation with alcohol or illegal drugs. Streissguth et al. (13) found that that 29% of adolescents with FAS or FAE/ARND had alcohol or drug problems
Adulthood
- For many affected adults, basic tasks of daily living, such as maintaining steady employment, managing money, and obtaining medical care present major challenges (54).
- Adults with FASDs experience significant work problems, and are much less likely to be able live independently (62).
- High rates of psychiatric disorders have been documented among adults with prenatal exposure to alcohol, including alcohol or drug dependence, depression, psychotic disorders, and various personality disorders (63).
- Streissguth et al. (13) reported that 60% of adults with FAS or FAE/ARND had problems with the law, and 50% had either been incarcerated or hospitalized in a psychiatric facility.
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