We see different types of people every day in life, I am pretty sure some of us have seen some smart dudes and have even bonded and exchanged ideas with them. During the course of interaction, our intelligence is put to test!and we wished that we were as smart as these set of people.


On the other hand, we may have also come across some people that are not as smart as they ought to be, and we may wonder what could have possibly gone wrong- why the wide discrepancy in the distribution of intellect.

To have a basic understanding of the intellectual disproportion, it might be ideal to understand the normal patterns in child development.

When we talk about normal development in childhood, we are talking about the development of skills like:

  • The ability of a child to sit without support, crawl, stand, walk at the required age of life (Motor skills).
  • The ability of a child to speak fluently and communicate with others (Language skills).
  • The ability to focus to initiate and finalize the art of concrete and abstract thinking and the ability to solve problems based on judgment ( cognitive skills).
  • The ability to interact with others, build relationships with immediate family, friends and the neighborhood without a conflict (social skills).
  • The ability to carry out special functions like writing on a book, creative drawing etc ( fine motor skills).



These developmental skills are age-specific meaning they ought to be acquired at a certain period of development in children.

An inability of a child to achieve any of these skills when they ought to have done so results in a concept called delayed milestone. When any of them is not achieved, the child is said to have missed a developmental milestone. This developmental milestone is what is accessed by the pediatrician for normal growth and development in children.

Interestingly, not everybody has a normal development in the childhood days, about one to three percentage of the general population come down with mental retardation. Tagging somebody as ‘mentally retarded ‘ In some countries could be derogatory, so a more subtle word ‘learning disability’ is usually preferred to the former.

Reading through this article would enlighten you on to the possible reasons why some individuals could end up mentally retarded!

The American Association on Intellectual and Developmental Disabilities (AAIDD) in 2010 defined Mental Retardation as :

a disability characterized by a significant limitation both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, practical and adaptive skills. This disability originates before the age 18.

In contemporary usage, Mental retardation could be used to describe a person that has a significant impairment ‘measured intelligence’. A concept usually based on the Intelligence Quotient ( IQ) which equals the mental age (M.A) divided by the chronological ( C.A) multiplied by 100 ie IQ = M.A /C. A x 100

It is usually recognized as a highly variable brain dysfunction in comparison to other individuals of the same physical and mental age.

For anybody to be diagnosed as mentally retarded, there are certain criteria to be met according to the Diagnostic and Statical Manual of Mental Disorders (DSM-IV ), A book by American Psychiatric Association

These include the presence of Concurrent deficits/impairment in 2 or more of the following areas:

  • Communications.
  • Self-care.
  • Home living.
  • Social & interpersonal skills.
  • Use of community resources.
  • Self-direction.
  • Functional Academics.
  • Health & safety.
  • Work & leisure.
  • IQ ≤ 70.


Now that you have a basic understanding of what mental retardation is all about, let us try to understand its possible causes.

There are a number of causes of mental retardation. For the purpose of this post, I will try to categorize them into these three groups for easy understanding

a) Biological,

b) Socio-environmental,

c) Combination of both,


In this group, I will further divide it into three sub-groups (prenatal, perinatal, postnatal) based on the circumstances surrounding the birth of the individual who eventually came down with mental retardation.


This simply refers to events that might have occurred before the formation of the sex gametes that would conceive the individual: Circumstances that could have lead to this include:

  • Intra-Uterine Infections – Infections not managed well during pregnancy could have an effect on the growing fetus.
  • Malnutrition During Pregnancy is another factor to be considered.
  • Single gene Abnormalities: I am sure we must have heard about different syndromes( a group of symptoms usually characterized together) in medicine. Down Syndrome( A genetic chromosomal disorder ) is one of the syndromes associated with mental retardation.
  • Brain Malformation- Hydrancephaly (A brain disorder in which part of the cerebral hemispheres are absent with a compensatory brain cavity filled with water is an example. Another is encephalocele ( a condition with an abnormal protrusion from the brain).
  • Placenta Malformations –The placenta which nourishes the developing fetus could be dysfunctional.


This subclass would involve all possible factors that could occur during the gestational period ( period of conception to delivery). This may account for about 10% of cases of mental retardation. Some of the possible factors include:

  • Prematurity – This is the term given to a birth that occurs before the 37th week of pregnancy (eight calendar months). Such individuals might have a chance of coming down with mental retardation if not managed by a specialist.
  • Birth Asphyxia – This is the term given to a newborn that could not ‘cry well’ at birth due to oxygen deprivation. As we know, oxygen is very important for brain functioning, and its deprivation maybe catastrophic to brain functioning.
  • Birth Trauma- If the circumstances surrounding the birth leads to trauma especially to the brain, there might be a chance of development of mental retardation 2


This refers to activities that might have occurred after delivery. Some of the possibilities include:

  • Head Injury- Trauma to the head during the childhood developmental stage may affect the normal brain functioning and the child may develop mental retardation.
  • Poison Exposure– Exposure to Carbon Monoxide can damage the brain.
  • Intra-Cranial Infections– Infection like Meningitis if not managed well may spell doom for the brain later on in developmental stages.
  • Deranged Levels of Electrolyte- Low levels of Magnesium (Hypomagnesaemia ) in the body and high levels of bilirubin (Hyperbilirubinaemia) in the blood can lead to brain damage.
  • Low Glucose- When there is reduced levels of glucose in the body (Hypoglycemia), it can also affect brain function


  • CHILD DEVELOPING ENVIRONMENT– The environment a child is exposed to also plays a part in building the mental health of the child.
  • NUTRITIONAL STATUS– Is also worthy of note because the brain development will be determined on the type it receives.
  • MOTHER FIGURE -The mother figure cannot be overemphasized, the mother figure is important for the development of bonding, attachment, and early learning behaviors

A combination of biological or socio-economic factors may be implicated in the causes.


Based on the Intelligence Quotient (IQ), There are four classifications of Mental Retardation.

  • Mild MR, IQ: 50-70 – This is the most common type seen. In the school years, these children develop like normal children but with very little deficit. The Mild Mental Retardation group are usually referred to as ‘educable’ because they can do better when they are provided with a little extra support


  • Moderate MR, IQ: 35-55- Children in this category often do not do so well at school and may drop out of school, however, when an extra attention is given to them, they can be educated. They are usually referred to as trainable!.

  • Severe MR, IQ: 20-40- This is usually discovered earlier in life due to a significant delay in milestones and also delayed speech.

  • Profound MR, IQ < 20-25- In this group, there are other associated physical disorders. They may need life-long support in a structured environment.

It is important to note that about 85% of individuals with MR are in the mild range, 10% fall in moderate and only about 5% are severe to profoundly retarded


The diagnosis would involve the following process by a specialist

• Detailed history

• Thorough physical examination

• Selected DNA or chromosome testing

• Neuroimaging if neurologic symptoms present

• Metabolic screening

• IQ tests – Wechsler scale, Bayley scale of infant development


Management of Mental Retardation is mostly aimed at the prevention of the causative factors.

  1. Education of the general public to address the misconception and myths about individuals with mental retardation and possible ways to prevent it is very important.
  2. Every birth should be attended by a skilled personnel to avoid birth complications.
  3. proper treatment of infection during pregnancy should be done by a specialist in the field.
  4. proper drug use during pregnancy and for women who intend to get pregnant should be ensured to prevent teratogenicity.
  5. Universal immunization of children with the recommended vaccines should be practiced always.
  6. Counseling of genetically at-risk parents should be done eg in a condition of Down syndrome.
  7. For those with the condition, it is important they are enrolled in a habilitation program.
  8. Proper school placement at the appropriate time and age


It is important to note that a diagnosis of Mental Retardation does not imply a constant state. It might be difficult for a layman to differentiate between mental retardation and other psychiatric conditions. but they can at least understand the factors that must have lead to the condition and offer help and support when necessary.

Thanks for reading!


curled from my steemit blog

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  1. James Diegel

    Wow – such a really well done and comprehensive post on such an important topic. I think that it really is a shame that people are not made aware of the issues and hardships that others are dealing with in their lives – and the more people are educated about the things, the better. I have always wondered actually why such topics have not been part of the core curriculum in schools, at least they were not at the ones I attended or worked in. Very well compiled Victor – I learned a lot 🙂

  2. AD

    You picked a very delicate topic and explained it very well, Victor.
    I’m not sure retardation is the right word. Retard means to be late or slow.
    Some of these people are faster than us, “normal people”. Maybe “mentally different ” would be better, no?
    Rated. *****

  3. Sam Adegoke

    Incredible and detailed post. I could remember that I wasn’t that sound while growing up, and it was due to my social behavioral pattern (environment) but I later cope with the challenges and built up myself personally. Thank you!