Chapter 5
Developmental Disabilities: Causes and
Classifications
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Causes of Developmental Differences
• Biological factors
– Biological insult refers to interference with or
damage to an individual’s physical structure
or functioning.
– Genetic disorders resulting in abnormal
biological development may be caused by
deviations in chromosomal structure or by
abnormal single genes.
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Causes of Developmental Differences
(continued)
– Chromosomal abnormalities are usually
biological accidents; that is, they are one-time
occurrences and do not affect future
pregnancies.
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Causes of Developmental Differences
(continued)
• Down Syndrome
– This condition is caused by three number 21
chromosomes.
– It is recognizable by a flat face, upturned
eyes, small ears, short stature, and the simian
crease.
– Heart and intestinal abnormalities are
common.
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Children with Down Syndrome
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Causes of Developmental Differences
(continued)
• Fragile X Syndrome
– Caused by a break on the X chromosome
present in males
– Sex-linked disorder given to sons by their
mothers
– Characterized by large ears, language delays,
autism-like behaviors, hyperactivity, and
delayed motor development
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Fragile X Syndrome
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What is Fragile X Syndrome?
•
•
•
Fragile X Syndrome is the leading cause of
genetically inherited mental impairment.
Symptoms range from mild learning
disabilities to severe mental retardation and
autism.
Challenging behaviors, social anxiety, and
speech and language delays are common
traits
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Causes of Developmental Differences
(continued)
• Metabolic disorders
– These cause a breakdown somewhere in the
complex chemical activities needed to
metabolize food.
– The breakdown can destroy, damage, or alter
cells.
– Metabolic disorders are single-gene defects,
such as PKU.
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Causes of Developmental Differences
(continued)
• Abnormal gene disorders
– Tay-Sachs, an accumulation of fatty tissues
around the brain that eventually leads to
death.
– Cystic fibrosis, a buildup of mucus in the
lungs, which makes it difficult to breathe.
– Breakthrough medical treatments are now
helping these individuals live longer and more
productive lives.
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Children with Cerebral Palsy
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Causes of Developmental Differences
(continued)
• Abnormal gene disorders (continued)
– Sickle-cell anemia, the red blood cells are not
formed correctly, making it difficult to navigate
the bloodstream. It is often accompanied by
joint pain and ulcers.
– Duchenne muscular distrophy, present in
males where the muscles deteriorate.
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Causes of Developmental Differences
(continued)
• Prenatal infections and intoxicants
– Rubella—can lead to devastating lifelong and
severe disabilities.
– CMV—at birth these children appear normal.
Later in life, they develop mental retardation,
deafness, and diseases of the eye.
– Herpes simplex—results in inflammation of
the brain and spinal cord.
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Causes of Developmental Differences
(continued)
• Prenatal infections and intoxicants
(continued)
– AIDS—passed to the unborn child through the
birth canal or breast milk—leaves a child’s
immune system helpless to fight off disease.
– Diabetes—maternal diabetes can leave
devastating effects on the child.
– Toxemia—women who experience toxemia
often deliver the baby prematurely, leading to
later complications.
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Causes of Developmental Differences
(continued)
• Prenatal infections and intoxicants
(continued)
– Alcohol and other drugs have been proven to
lead to birth defects such as fetal alcohol
syndrome and fetal alcohol effect.
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Causes of Developmental Differences
(continued)
• Maternal malnutrition and protein
deficiency
– Lack of protein during the first trimester can
lead to immature development of the brain
and nervous system.
– It can also lead to small babies that are born
prematurely.
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Causes of Developmental Differences
(continued)
• Birth complications
– Lack of oxygen to the brain—anoxia can
occur.
– Premature babies can suffer hemorrhaging.
– C-sections may need to be performed if the
life of the mother or infant is in danger.
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Causes of Developmental Differences
(continued)
• Complications following birth
– Meningitis—a virus or bacterial infection that
causes inflammation of the protective
covering of the brain and the spinal column—
can lead to brain damage.
– Encephalitis—swelling of the brain—can also
lead to brain damage.
– Lead poisoning—poisoning from lead found in
lead-based paint and older homes.
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Poverty
• Nutritional deficiency
– Children living in poverty have inadequate
nutrition.
– WIC was designed to eliminate some of the
counter effects of poverty.
– WIC provides funds to pregnant mothers and
then their newborn to purchase healthy foods.
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Poverty (continued)
• Inadequate health care and education
– Living in poverty, many women do not seek
out prenatal care, leaving themselves open
for premature labor and other complications.
– Regular medical checkups are also good for
the newborn child.
– Without health insurance, good care is not
always possible, so immunizations fall behind.
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Poverty (continued)
• Homelessness and substandard housing
– Living in these conditions can cause health
problems by being exposed to contaminants
in the environment.
• Single-Parent Families
– Single mothers in particular tend to work
multiple jobs, leaving their children
unattended or with little supervision.
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Poverty (continued)
• Child Care
– Quality child care can combat the effects of
poverty, but people living in poverty cannot
often afford quality.
– Centers need to offer the best with what they
have, making quality available to all.
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Poverty (continued)
• Combating poverty
– Early intervention and care can eliminate
some of the effects of poverty and give
children the chance to be successful in life.
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Classification of Developmental
Disabilities
• To receive funding, children must be
categorized. The following are categories
approved by the federal government:
– Specific learning disabilities, having a deficit
between IQ and ability
– Speech and language disorders, having
difficulty with receptive or expressive
language
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Classification of Developmental
Disabilities (continued)
– Mental retardation—IQ is 70 or below, and
there are significant delays in other areas of
development as well.
– Emotional disorders—children have difficulty
controlling behavior and reading emotional
cues.
– Multiple disabilities—a combination of one or
more disabilities.
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Classification of Developmental
Disabilities (continued)
– Hearing loss—a hearing loss so severe that
individuals cannot process spoken language,
even with hearing aids or other forms of
amplification.
– Orthopedic impairments—a child has limited
use of the limbs.
– Health impairments—the child has difficulty
maintaining developmental milestones due to
health problems.
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Children with Hearing Impairments
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Classification of Developmental
Disabilities (continued)
– Visual impairments—the children’s vision is
so poor that they cannot use that sense to
learn from their environment.
– Combined vision and hearing loss—a child
has loss of both vision and hearing and incurs
learning difficulties form them.
– Autism—a child retreats into “his or her own
world,” language often stops, and the child
begins to turn inward.
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Children with Visual Impairments
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Classification of Developmental
Disabilities (continued)
– Traumatic brain injury—this category of
injuries (either open- or closed-wound) to the
head cause tearing of the nerve fibers,
bruising of the brain against the skull, or
bruising of the brain stem.
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Children with Speech Impairments
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Children with Serious Emotional
Disturbances
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Children with Spina Bifida
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Children with Autism
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Children with Health Impairments
Sickle cell anemia
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Boy with Diabetes
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Dyslexia
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ADD