Causes of speech and language disorders

There are a variety of causes of speech and language disorders.
  • Congenital syndromes
  • Disorders of the prenatal environment
  • Syndromes acquired after birth
  • Factors that may contribute to a speech-language disorder
Congenital Syndromes are present at birth.  Some congenital syndromes that can cause language disorders include genetic syndromes, chromosomal syndromes, or metabolic disorders.
  • Genetic Syndromes are transmitted through genes and can be passed along from a parent to their child.  Some genetic syndromes that may affect speech-language development include Fragile X Syndrome and congenital deafness.
  • Chromosomal syndromes occur when there is an abnormality within a person's genetic makeup.  Some chromosomal syndromes that may affect speech-language development include Turner Syndrome, Pierre Robin, Cri du Chat Syndrome, Klinefelter Syndrome, and DiGeorge Syndrome.
  • Metabolic disorders affect a person's growth, development, and subsequent learning.  Some metabolic disorders that may affect speech-language development include PKU (phenylketonuria), thyroid disorders, Hunter Syndrome, and Hurler Syndrome.
 
Disorders of the prenatal environment can be caused by a mother's contraction of, or exposure to, a particular disease or toxin.  The most common virus that results in language impairment in the child is rubella.  Other diseases that affect language development include HIV/AIDS, herpes simplex, and chicken pox.  Toxins, such as radiation (X-rays), alcohol, tobacco, and drugs can also effect the unborn child and result in language impairment.  Fetal Alcohol Syndrome (FAS) may occur when a woman consumes alcohol during her pregnancy.  FAS can cause a variety of difficulties, including speech and language disorders.
 
Syndromes acquired after birth can be caused by oxygen deprivation to the brain, infections, toxins, and traumatic brain injuries.  Respiratory disorders or lack of oxygen to the brain during or shortly after birth can cause brain damage, leading to language impairment.  Infections, such as measles, mumps, and meningitis, and toxins, such as lead and poisons, can cause language impairment.  Traumatic brain injuries from falls or accidents may also cause language impairments.  Another cause of traumatic brain injury in infants is Shaken Baby Syndrome.
 
There are many factors that may contribute to a speech-language disorder.  When speech-language disorders are not associated with any other syndrome or disability, they are known as Specific Language Impairments.  Usually, the definite cause is unknown, but there are a variety of factors that may or may not have influenced the speech and language development of that child.  These include:
  • Familial tendency - Specific-Language Impairment tends to run in families, however there is not a known genetic link at this time.  Currently, studies are being conducted to learn more about a possible genetic link.
  • Middle ear infections - Middle ear infections are extremely common among young children.  A middle ear infection may cause a temporary hearing loss.  When a child has frequent ear infections, at a young age during critical periods, they can miss out on sounds and language in their environment, causing a delay in their development.
  • Environment - Children need a lot of language stimulation in their environment and exposure to language in a variety of ways.  When children are deprived of language stimulation early in their development they may not learn the sounds and rules of language.  When caregivers respond to their child's pointing and grunting, the child doesn't perceive the need to use words to control his/her environment.  Sometimes, an older sibling may "talk" for the child, also decreasing the need for the child to develop his/her speech and language.  Environments that are not rich in language and new experiences can decrease the child's exposure to language and delay their development.  
Some speech-language disorders have no known cause. 
Specific Language Impairment, Specific Learning Disability, and Autism are among those that still have an unknown etiology.
 
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