Allen Chapter 5

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All Rights Reserved.
Chapter 5
Developmental Disabilities: Causes and
Classifications

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.
– Syndromes are groupings of similar
characteristics known as stigmata.

(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.

(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.

(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.

(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.

(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 dystrophy
• Present in males where the muscles deteriorate.

(continued)
• Prenatal infections and intoxicants
– Rubella
• Leads to devastating lifelong and severe
disabilities.
– CMV
• Children appear normal at birth. Later in life, they
develop intellectual disabilities, deafness, and
diseases of the eye.
– Herpes simplex
• Inflammation of the brain and spinal cord.

(continued)
(continued)
– AIDS
• Can be passed to the unborn child through the
birth canal or breast milk and leaves a child’s
immune system helpless to fight off disease.
– Maternal diabetes
• High risk for developmental problems in child.
– Preeclampsia (toxemia)
• Complications that can lead to death in mother and
infant.

(continued)
(continued)
– Alcohol and other drugs have been proven to
lead to birth defects such as fetal alcohol
syndrome and fetal alcohol effect.
– Poor nutrition including lack of protein can
lead to low birth weight, illness and higher risk
of death in first year of infant’s life. Poor
nutrition can also damage the developing
brain and nervous system.

(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.

(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 lead to brain damage.
– Lead poisoning
• Poisoning from lead found in lead-based paint and
older homes can damage nervous system.

(continued)
• 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.

Causes of Developmental
Differences (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.

(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.

(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.

Classification of Developmental
Disabilities
• Categories of disability under IDEIA
– Specific learning disabilities
• A disorder in one or more of the basic
psychological processes involved in using
language, spoken or written.
– Speech and language disorders
• Difficulty with receptive or expressive language.

Disabilities (continued)
– Developmental delay
• Delay in one or more of the developmental
domains.
– Intellectual disability
• Sub-average general intellectual functioning along
with deficits in adaptive behavior.
– Emotional disturbance
• Behavioral or emotional responses that are
different from age, ethnic or community norms.

– Multiple disabilities
• A combination of one or more disabilities.
– Hearing impairment and deafness
• Hearing impairment is a hearing loss that
adversely affects educational performance.
• Deafness is a hearing loss so severe that
individuals cannot process spoken language, even
with hearing aids or other forms of amplification.

Classification of Developmental Disabilities
(continued)
– Orthopedic impairments
• Developmental problems that interfere with walking
or other body movements.
– Other health impairments
• Limited strength, vitality, and alertness.

– Visual impairments
• A range from partially sighted to blind.
• Individuals who are partially sighted read large
print or possibly regular print.
• Individuals who are blind have a severe enough
vision loss that they cannot read print.
– Combined deafness and blindness
• A child has loss of both vision and hearing.

– Autism
• Developmental disability significantly affecting
verbal and nonverbal communication and social
interaction.
– 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.

A Final Thought on Categories
• Each category describes a condition that
makes a student eligible for a free and
appropriate public education.
• To meet the definition, a child’s
educational performance must be
adversely affected by the disability.
• Category does not prescribe the services
for a child but a program should be
planned based on individual needs.

Allen Chapter 5

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