In the previous article regarding intellectual and developmental disabilities, the parent/caregiver was presented an introduction with respect to the prevalence and changes in this area of human living as well as its application. Part I of this article will review many of the causes of intellectual and developmental disabilities. Part II will cover many preventive measures that may be taken in the fight against intellectual and developmental disabilities.
The research and study of intellectual and developmental disabilities over the past 50 years or so have determined there are nearly 800 causes of this disability. The causes associated with intellectual and developmental disabilities have been categorized by the American Association for Intellectual and Developmental Disabilities (AAIDD) as Prenatal (occurring before birth), Perinatal (occurring during or shortly after birth) or Postnatal (occurring after birth). All of these factors associated with intellectual and developmental disabilities are classified as having a biological or environmental (social, behavioral, educational) basis.
The Table below presents a brief picture of the causes for intellectual and developmental disabilities among infants and children:
Causes/Risk Factors For Intellectual And Developmental Disabilities
Causes Biomedical Social Behavioral Educational
Prenatal 1. Chromosomal disorders
2. Single-gene disorders
4. Metabolic disorders
5. Cerebral dysgenesis
6. Maternal illnesses
7. Parental age 1. Poverty
2. Maternal malnutrition
3. Domestic violence
4. Lack of access to prenatal care 1. Parental drug use
2. Parental alcohol use
3. Parental smoking
4. Parental immaturity 1. Parental cognitive disability without supports
2. Lack of preparation for parenthood
2. Birth injury
3. Neonatal disorders
1. Lack of access to birth care
1. Parental rejection of care- taking
2. Parental abandon- ment of child
1. Lack of medical referral for intervention services at discharge
1. Traumatic brain injury
3. Meningo – encephalitis
4. Seizure disorders
5. Degenerative disorders
1. Impaired child caregiver
2. Lack of adequate stimulation
3. Family poverty
4. Chronic illness in the family
1. Child abuse and neglect
2. Domestic violence
3. Inadequate safety measures
4. Social deprivation
5. Difficult child behaviors
1. Impaired parenting
2. Delayed diagnosis
3. Inadequate early intervention services
4. Inadequate special – educational services
5. Inadequate family support
Source: The American Association on Intellectual and Developmental Disabilities (AAIDD). (2002). Intellectual and
Developmental Disabilities: Definition, classification, and systems of supports (10th ed.). Washington, DC
Those who study intellectual and developmental disabilities have found that about 50% of mild cases and 30% of severe cases is unknown. However, learning about the causes is critical to lowering the incidence of intellectual and developmental disabilities. With greater knowledge and understanding could have positive implications for educational, employment and social intervention of a child later in her or his life.
Biomedical Causes. Certain biomedical causes have been found in about 66% of individuals with more severe forms of intellectual and developmental disabilities. It is important to notice that none of the factors in the above chart is an intellectual and developmental disability in and of itself. The conditions, diseases and syndromes are generally associated with intellectual and developmental disabilities. They may or may not result in intellectual and adaptive functioning that define intellectual and developmental disabilities. For example, malnutrition, birth related injuries, Down’s Syndrome (Trisomy 21), only causes intellectual and developmental disabilities when it results in impaired intellectual and adaptive functioning to meet the criteria for a diagnosis. Some of the conditions, on the other hand, may lead to the disability if permitted to persist and treatment is not obtained. This also means intellectual and developmental disabilities may be acquired.
The term syndrome pertains to a number of symptoms that occur together to provide one or more defining features of a named disease or condition. Down’s syndrome and fragile-X syndrome are the two most recognized causes of inherited forms of intellectual and developmental disabilities.
Environmental Causes. Persons with mild intellectual and developmental disabilities, who make up about 85% of all individuals, generally do not need the same level of social or educational support. In the majority of cases, researchers found no brain damage or other biological problems to be the cause of the disability. When no biological factors can be found, some researchers present the cause or causes to be due to a poor social/cultural environment or maybe even abuse, neglect, and sensory deprivation. No direct proof has been found in the research literature to support any notion that these influences are responsible for mild forms of intellectual and developmental disabilities. So far these are theories as a mean to explain the presence of a disability when biological factors are not present.