Causes

1
Causes of Mental Retardation
2
Prenatal Causes

• Chromosomal disorders
• Inborn errors of metabolism
• Developmental disorders affecting brain
  formation
• Environmental influences

3
Chromosomal Disorders

• Down syndrome A condition resulting form
  abnormality with the 21st pair of
  chromosomes characterized by mental
  retardation and such physical signs as
  slanted appearing eyes, hypotonia, shortness,
  and tendency toward obesity
• Trisomy 21 type of Down syndrome in which the
  21st chromosome is a triplet
• Spina Bifida a congenital midline defect
  resulting from failure of the bony
  spinal column to close completely during
  fetal development
• Williams Syndrome a condition resulting from
  deletion of material in the 7th pair of
  chromosomes

4

• Fragile X Syndrome condition in which the
  bottom of the X chromosome in the
  23rd pair of chromosomes is pinched
  off
• Prader-Willi syndrome caused by inheriting
  from ones father a lack of genetic material
  on the 15th pair of chromosomes

5
Inborn Errors of Metabolism

• Phenylketonuria (PKU) - metabolic genetic
  disorder caused by the inability of the body
  to convert phenylalanine to tyrosine
  accumulation of phenylalanine results in
  abnormal brain development

6
Developmental Disorders of Brain Formation

• Microcephalus condition causing development of
  a small, conical- shaped head proper
  development of the brain is
  prevented, resulting in mental retardation
• Hydrocephalus condition characterized by
  enlargement of the head because of
  excessive pressure of the
  cerebrospinal fluid

7
Environmental Influences

• Fetal Alcohol Syndrome (FAS) Abnormalities
  associated with the mothers drinking
  alcohol during pregnancy defects range
  from mild to severe
• Rubella serious viral disease, which, if it
  occurs during the first trimester of
  pregancy, is likely to cause deformity in the
  fetus

8
Perinatal Causes

• Anoxia deprivation of oxygen can cause brain
  injury
• Low birth weight babies who are born weighing
  less than 5.5 pounds usually premature at
  risk for behavioral and medical conditions,
  such as mental retardation
• Syphilis venereal disease that can cause
  mental subnormality in a child,
  especially if it is contracted by the
  mother-to-be during the latter stages
  of fetal development
• Herpes Simplex viral disease that can cause
  cold sores or fever blisters if
  it affects the genitals and is contracted
  by the mother-to-be in the later stages
  of fetal development, it can
  cause metnal subnormallity in the
  child

9
Postnatal Causes

• Traumatic Brain Injury injury to the brain
  resulting in total or partial
  disability or psychosocial maladjustment that
  effects educational performance
• Meningitis bacterial or viral infection of the
  linings of the brain or spinal cord
• Encephalitis inflammation of the brain can
  affect the childs mental development
  adversely