fetal alcohol syndrome
Fetal Alcohol Syndrome (FAS) is the most commonly identifiable cause of mental retardation. Due to the fact that alcohol freely crosses the placenta, it has a range of effects on the developing fetus. These effects vary depending how much alcohol is consumed and during which part of fetal development the consumption occurs. The greatest risk of exposure is during the first twelve weeks of pregnancy. In the US, 1 in every 500-1000 births is affected by maternal alcohol use.
Maternal drinking during pregnancy does not always result in FAS. Most children affected by alcohol exposure before birth do not have the characteristic facial abnormalities and growth retardation identified with FAS, but they do have brain and other impairments that are just as significant. These children are referred to as having Alcohol-Related Neurodevelopmental Disorder (ARND). This was formerly referred to as Fetal Alcohol Efffect (FAE).
Fetal Alcohol Syndrome is formally defined by four criteria.
- maternal drinking during pregnancy
- characteristic facial appearance (which diminishes with time except for microcephaly)
- microcephaly (head circumference below 5th percentile)
- eyes widely spaced with short eye slits
- short, upturned noses
- thin upper lips
- flattened philtrum (groove in the midline of the lips)
- growth retardation
- brain damage, specific areas that are most commonly affected are:
- the basal ganglia, which are associated with memory and cognition
- the cerebellum, which controls balance, gait coordination and some cognitive functions
- in 7% there is an absence of the corpus callosum, the framework that links the two sides of the brain
Twenty to fifty percent of individuals with FAS also have congenital heart defects, benign tumours of blood vessels, genitourinary malformations and/or minor joint and limb abnormalities. Vision and hearing complications are also common.
Early development (birth to 2 years) shows delays in speech and language as well as low muscle tone associated motor delays. These problems recede somewhat by school age, and are manifested mostly as clumsiness and fine motor coordination problems.
By Kindergarten age, children with FAS/ARND show a wide range of intellectual functioning, but most exhibit mild mental retardation. They tend to have difficulties in executive function (involving planning, sequencing, self-monitoring and goal-directed behaviours). These difficulties will affect ability to follow classroom routines, independence in daily living skills and other adaptive behaviours and impede social skills development.