Fetal alcohol spectrum disorders: Summary of Neuropsychological and behavioral features (2011) - Mattson et. al. - Article

Summary of the article Fetal alcohol spectrum disorders: Summary of Neuropsychological and behavioral features (2011) - Mattson et. al.

It’s very difficult to understand the variability of neurobehavioral outcomes of prenatal alcohol exposure without identifying the dose and pattern of alcohol consumption as well as developmental timing of exposure. The amount of alcohol is correlated with the severity of outcome, but the pattern of alcohol exposure can often moderate these effects, with binge drinking resulting in more severe deficits than chronic exposure. The timing of exposure can also influence the pattern of severity of structural and functional abilities.

Impairments in individuals with FAS

Diminished intellectual capacity is one of the most common findings among children exposed to alcohol during pregnancy. These intellectual impairments can even occur in the absence of facial features and growth retardation. The average IQ estimate of individuals with heavy prenatal alcohol exposure is 70 in individuals with FAS and 80 for those without dysmorphic features. IQ is also highly correlated with psychopathology, children with some form of intellectual disability experience greater psychiatric disturbance. A lot of research has been conducted on this subject, but there are a lot of discrepancies between studies, especially about the effects of lower exposure (one to three drinks per week).

Executive functions are related to brain areas found to be vulnerable to alcohol exposure. They have been widely defined as the ability to maintain an appropriate problem-solving set for attainment of a natural goal. Children who have prenatally been exposed to alcohol are delayed on executive function task, like problem solving. They have difficulties forming and identifying abstract concepts and shifting to new conceptual categories. This, in combination with troubled analytic thinking, impairs their problem-solving abilities.

The impaired executive functions also cause deficits in verbal and non-verbal fluency, especially letter fluency. The same accounts for inhibitory control. Infants prenatally exposed to alcohol have a weak response inhibition. This may be related to an impaired Theory of Mind, as poor performance on theory of mind measures has been found to correlate with a inhibition control task in children with prenatal alcohol exposure.

Furthermore, alcohol-exposed children experience difficulties with holding and manipulating information in working memory. This accounts for both their verbal working memory as their visual-spatial working memory. It’s important to understand these deficits, because these processes often underlie other executive control and attention skills.

The hippocampus has been shown to be particularly sensitive to prenatal alcohol exposure. It therefore isn’t surprising that learning and memory deficits in children with prenatal alcohol exposure often occur. For example, they show deficits in both learning and recalling verbal information, although research suggests that these abilities might improve with age in less affected children. Nonverbal learning and memory is also impaired in children with FAS.

There are mixed findings about the effect of prenatal alcohol exposure on language development. Speech and language impairments have been found, ranging from an absence of comprehensive speech to mild dysarthria or lisping. They show grammatical and semantic difficulties, problems with word comprehension, lack in their naming abilities and their expressive and receptive skills. In their social interactions, children with FAS also struggle. They have problems balancing between linguistic and social cognitive task demands. Thereby, they provide not enough organization and information for listeners in narratives. They also often fail to consider the perspective of the listener during interaction.

Despite limited research in this area, deficits in visual-spatial perception and construction have been reported in children with histories of prenatal alcohol exposure. This seems to be logical, since these functions are also linked to the hippocampus, earlier discussed to be highly sensitive to prenatal alcohol exposure. Also, impairments in both fine and gross motor skills have been reported in children with FAS. These skills highly depend on the cerebellum and basal ganglia, which also appear to be very sensitive to alcohol exposure. Furthermore, abnormalities in the central nervous system and peripheral motor nerve damage can also be the effect of alcohol exposure and cause motor deficits. Delayed skeletal maturity and skeletal malformation of the hands and feet are also symptoms of FAS and contribute to difficulties in motor functioning.

Affected children show deficits in attention on neuropsychological tasks of reaction time, vigilance and information processing. A lot of children suffering from FAS also get diagnosed with ADHD or hyperkinetic disorder. They also have difficulties with academic function in verbal domains but especially in mathematical domains, even after controlling for IQ. This has emerged as a specific area of weakness.

Next to neuropsychological deficits children with FAS often exhibit, they are also likely to present clinically significant and maladaptive behavioral characteristics. Parents of children with FAS report more behavioral and emotional disturbances, as do the children themselves in self-reports. They show different externalizing behaviors such as aggressive behavior and social problems. Although research is short in this area, internalizing problem behaviors also seem to occur in children with FAS. Prenatal alcohol exposure has been associated with negative affect and increased risk for developing a major depressive disorder in childhood. This is part of the increased levels of secondary disabilities and psychiatric diagnoses that are common consequences of prenatal alcohol exposure.

Studies have suggested that children with prenatal alcohol exposure are more likely to show delinquent behavior, because they can exhibit impaired moral decision-making abilities. These behavioral difficulties often persist into adulthood and often result in adverse life outcomes like trouble with the law and substance abuse. These adverse life outcomes may be related to deficits in adaptive functioning which play an important role in daily living skills, communication and socialization.

Neurobehavioral Profile

It would be useful to identify a neuropsychological profile of strengths and weaknesses to make FAS more easy to identify and to target specific domains for clinical intervention. The weaknesses of the profile of children with FASD have been discussed in the paragraph above. Lack of impairment, or relative strengths are present in auditory attention, retention of verbal information and basic language function. For future research it might be good to compare children with prenatal alcohol exposure to those who show clinically similar behaviors in order to determine patterns that might distinguish these groups.

Comparing children with FASD and children with ADHD, separate neurobehavioral profiles have been found. They show unique attention profiles. The four factor model of attention is divided in Focus, Sustain, Encode and Shift. Where children with ADHD show impairments in the areas of focus and sustain, children with FASD seem to be more troubled in encoding and shifting their attention. Variations in attention profiles have also been found to depend on gender in children with FAS, with or without ADHD. Girls with FASD and ADHD showed a significant impaired ability to sustain attention and encode information compared to girls with FASD but without ADHD. This effect was reversely found in boys. Differences between children with and without ADHD were also found in other cognitive abilities and motor competence. Research suggested that children with ADHD showed problems with both basic and complex motor skills, while children with FASD have more trouble integrating these functions into coordinated, complex motor skills. Comparing children with FASD to children without prenatal alcohol exposure but with similar IQ’s, differences and similarities were also found.