A Study and Analysis of Biological Factors That Can Cause Mental Retardation in Children

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The purpose of this paper is to ascertain and analyze the numerous factors that can cause early mental retardation in children, looking especially at factors that influence the child's development before they are actually born. These factors include some obvious factors such as drinking or taking drugs while pregnant or Shaken Baby Syndrome. However, there are also equally serious, yet more difficult to detect, factors that can lead to retardation that will be addressed as well, such as exposure to certain toxins in early childhood. This paper will examine these factors in detail and assess the severity and risk involved in each.

A Study and Analysis of Biological Factors That Can Cause Mental Retardation in Children

In children, especially newborns, early signs of mental retardation may make themselves apparent unexpectedly. While their appearance is unfortunate for all parties involved, most of the time, the reason for this retardation may be traced back to certain behaviors or habits of the mother, or, in some cases, bad genetics produces conditions such as phenylketonuria. However, the majority of these factors have concrete causes that the retardation may be traced back to. This allows researchers to diagnose exactly how and why each specific factor contributes to mental retardation and what may be done to limit both exposure to these factors as well as ways to diminish their effects. First, it is important to study and discuss some of the more prominent factors that lead to mental retardation in children in order to understand just how these factors work and what may be done about them in the future.

Perhaps the most prominent factor leading to mental retardation in children from an early age is fetal alcohol syndrome, caused by the abuse of alcohol by the mother during pregnancy of the child. Fetal alcohol syndrome tends to manifest itself early, since the effects of it are both mental and physical, although the severity of either the physical or mental effects of fetal alcohol syndrome may vary (Sampson et al, 1997). In terms of how alcohol actually affects the development of the fetus and leads to fetal alcohol syndrome, there are a number of factors, and even now scientists are not certain of what does or does not specifically contribute to fetal alcohol syndrome, but obviously, the most prominent offender is the ingestion of alcohol by the mother (Sampson et al, 1997). The actual effects of fetal alcohol syndrome are caused by the alcohol from whatever alcoholic beverage the mother ingested crossing over the placental barrier, which can lead to a number of negative effects in the child, all of which contribute to fetal alcohol syndrome, such as added weight to the child, facial distortions, stunted growth or, perhaps most importantly, the breaking down of neurons, which is what leads to the mental problems in children with fetal alcohol syndrome (Sampson et al, 1997). Further evidence of the detrimental effects of alcohol may be found in one study, which found that alcohol, when ingested during pregnancy, is well established as a teratogenic drug capable of causing miscarriage, stillbirth, malformation, growth deficiency, and central nervous system dysfunction by interfering with normal proliferation and migration of neuronal and glial cells, by direct toxic effects of ethanol and acetaldehyde upon cells, by hemodynamic-induced hypoxia, and by other mechanisms (Sampson et al, 1997). Essentially, this means that alcohol is one of the most harmful substances that an unborn child may be exposed to, and is one of the leading causes of mental retardation to children because of the damage it causes during pregnancy to the structure of the brain as well as the central nervous system after birth. The surest way to ensure this does not happen is to simply abstain from the drinking of alcohol during pregnancy.

Another important factor that oftentimes leads to the retardation in children is perhaps more obvious: physical trauma, often from things like shaken baby syndrome, which can cause damage to many parts of the baby, but does the most damage to the head and brain, since the is disproportionately large in the first few years of a child's development. Shaken baby syndrome is actually an umbrella term for three different conditions caused by the shaking of a baby: retinal hemorrhage, cerebral edema, and subdural hematoma, each of which will be addressed (Baby, 2007). First, subdural hematoma is, quite simply, a type of bruise that causes blood to coagulate in outer parts of the skull and brain, which leads to a number of problems, the most prominent being an increase in pressure of the cranium, which causes compression in the brain and causes damage to the brain tissue within (Bab,y 2007). Oftentimes, these subdural hematomas are fatal if not addressed quickly, but may oftentimes cause mental retardation in children, as the damage to the brain becomes severe enough to significantly impact the development of the child. The second main consequence of shaken baby syndrome is cerebral edema. Cerebral edema is similar to subdural hematoma in that they both involve an excess of fluid reaching the brain, save that cerebral edema has a tendency to quickly break down the shield between the brain and the rest of the skull, leading to a number of problems, the most notable of these being an excess in water, which then moves into the brain cells, causing minor to severe brain damage and more than likely causing at least some form of mental retardation in the child (Baby, 2007). The last element of the shaken baby syndrome is known as retinal hemorrhaging, and differs from the other two elements in that retinal hemorrhaging does not directly affect the brain itself, instead causing disorders of the eye (Baby, 2007). Since they do not affect the brain or its development, retinal hemorrhaging is not seen as a large threat to the mental development of a child, so retinal hemorrhaging is most likely not a contributing factor to mental retardation in children, although it can still cause significant damage to the retina if a severe case of retinal hemorrhaging goes untreated. Nevertheless, these problems that are caused by shaking the baby or generally being too rough with handling may be easily prevented by being gentle with any sort of physical contact with a child, especially within their first few years of development. The head of newborn children is especially delicate, and, as a result, many cases of retardation arise very early, especially in cases of mishandling of the baby, which inevitably leads to a laundry list of problems with the brain, which, of course, then translate to differing forms of mental retardation in the child (Baby, 2007).

Another biological factor that can cause mental retardation in children is exposure to toxins in early childhood. This differs from fetal alcohol syndrome in that fetal alcohol syndrome influences development only within the pregnancy itself, whereas exposure to toxins occurs after birth, oftentimes as a result of careless parenting. Perhaps one of the worst offenders in terms of toxins causing mental retardation in children is lead, which can be found on a number of different types of children's toys, mostly within the paint, which many children then put in their mouths and indirectly ingest. This lead is extremely harmful to children, especially newborns and toddlers, because the lead is extremely toxic to the nervous system, especially in children, and has lead to observable decreases in intellect in those that have had a great deal of exposure to lead (Koller et al, 2004). Furthermore, lead exposure has been linked to learning disabilities in young children, further cementing its status as a toxin that may cause a serious threat of mental retardation in children (Koller et a,l 2004). The lead itself is also a greater threat to children because children retain more of the lead after being exposed to it, giving it more time to cause detrimental effects to their mental health (Koller et al, 2004). Evidence has shown that even low levels of lead can have subtle yet nonetheless detrimental effects to the nervous system of young children, which directly affects development and could lead to the onset of mental retardation if they are exposed for long enough to lead, even in low doses (Koller et al, 2004). Lead affects children by inhibiting the synthesizing and creation of necessary chemical and processes that are needed for strong mental health in children, the most notable of these being the synthesizing of heme, which is a primary component of hemoglobin, which forms the blood of a human (Koller et al, 2004). Inhibiting the development of heme has a number of negative effects on its own, of course, but the brain is one of the most sensitive organs in the human body, and any loss of inhibition of the development of necessary ingredients and chemicals can have profound negative effects in the development of a child, which leads to mental retardation, eventually, as the lack of heme leads to less and lower quality blood within a child (Koller et al, 2004). Furthermore, lead is extremely common even in today's world, and children are frequently exposed to even small quantities of it via ingestion (in fact, one study estimates that the average child ingests about <mg per day of soil, on average, which contains traces of lead due to paints and other contaminants working their way into the soil), and is especially problematic for children with pica, which causes them to have an appetite for non-edible materials such as paper or soil (Koller et al, 2004).

The final biological cause of mental retardation in children is simply bad genes, oftentimes referred to as "genetic anomalies" (Zigler, 1986, p. 8). These genetic anomalies can lead to a large number of differing types of mental retardation, although perhaps one of the most infamous is Down syndrome (Zigler, 1986). Down syndrome is caused by the presence of an extra chromosome: a third chromosome 21, to be exact and can lead to stunted IQ and mental retardation at even a young age (Zigler, 1986). However, unlike many of the other factors that lead to mental retardation, Down syndrome may be largely ameliorated with proper care of those with the deficiency, which may eventually allow the sufferer to lead a normal way of life, eventually. Nevertheless, Down syndrome remains a potent threat of mental retardation for children. Another common genetic factor leading to mental retardation is Tay-Sachs disease, which causes a degradation of cells within the nervous system, much like lead exposure, and can have profound impacts on the psychological development of a child, often leading to retardation at an extremely early age, or even death, in the worst-case scenarios (Zigler,1986). Tay-Sachs disease causes an accumulation of gangliosides in the nerve cells of the brain, which causes severe degradation of the brain and is very difficult to prevent since there is currently no known cure for Tay-Sachs disease (Zigler, 1986). While these genetic factors are unfortunate, there is little that may be done about them until or unless gene-splicing becomes practical, in which case the genes that lead to these various diseases may be simply removed, although such technology might not even exist for a number of years.

These biological factors that lead to mental retardation in children are actually in the minority. In actuality, about 50 percent of cases of retardation in children are completely unknown, even after a thorough inspection of the patient and their medical and genetic history (Zigler, 1986). It is likely that many cases of mental retardation in children are caused by a combination of factors, such as neonatal drinking, rough handling of the baby, and intake of small doses of lead, which may over time develop into a case of mental retardation. Another aspect of mental retardation in children to remember is that oftentimes, the causes are entirely preventable. Simple steps like refraining from drinking, and handling newborns with care, will do wonders for preventing mental retardation. Many companies are also doing their part to reduce the amount of lead in their products, leading to generally safer toys for children, although it is never advisable to have them ingesting or chewing on these toys in the first place. Mental retardation also has a number of levels and definitions, so even children exposed to these factors might only come out with a minor case of mental retardation. Either way, the basic steps that may be taken to reduce the risk of mental retardation of children by the parents should be practiced by everyone. Many times, the mental retardation that stems from habits such as drinking and rough handling are merely indicators of other, perhaps even more serious symptoms, such as cranial hemorrhaging, which could even cause death in the child if not treated right away. Children at least deserve to receive a fair shot at life, and denying them this chance by carelessly handling them or drinking is simply not acceptable. The ingestion of lead as another possible factor leading to mental retardation is another compelling reason to keep a close eye on children at all times, as mental retardation may still manifest itself even after the first initial years of a child's life.


Baby, S. (2007). Shaken baby syndrome. UTMJ Grand Benefactor-> $100, 5. 6-14. 22-27.

Koller, K., Brown, T., Spurgeon, A., & Levy, L. (2004). Recent developments in low-level lead exposure and intellectual impairment in children. Environmental Health Perspectives, 112(9), 987. 1-14.

Sampson, P. D., Streissguth, A. P., Bookstein, F. L., Little, R. E., Clarren, S. K., Dehaene, P. & Graham, J. M. (1997). Incidence of fetal alcohol syndrome and prevalence of alcohol-related neurodevelopmental disorder. Teratology, 56(5), 317-326.

Zigler, E. (1986). Understanding mental retardation. Cambridge University Press. 8-15.