Developmental disabilities are impairments in a child’s physical, learning, cognitive (thinking, reasoning, or remembering), language, and behavioral development. These impairments begin during the child’s developmental period and may affect day-to-day functioning. Developmental disabilities often last throughout a person’s lifetime.
There are six major types of developmental disabilities including ADHD, ASD, cerebral palsy, hearing impairment, intellectual disability, and vision impairment.
ADHD is characterized by uncontrollable impulsive behaviors, trouble paying attention, and being overly active. One of the most common mental disorders in children, ADHD affects an estimated 8.4% of children and 2.5% of adults. More boys live with ADHD than girls, and the condition causes distress and/or problems functioning at school, with friends, and at home.
ASD typically begins before the age of three. In some cases, this developmental disability is caused by a genetic condition. In others, the cause is unknown. People living with ASD may look different, they may have advanced communication skills, or they may be nonverbal. Some people living with ASD might need around the clock help with day-to-day activities. Others may live and work on their own without the need for support.
Cerebral palsy is a developmental disability that affects muscle tone, movement, balance, and posture. Cerebral palsy is often discovered in infancy or during the preschool years. The severity of cerebral palsy varies. Some people living with cerebral palsy can walk and have no apparent intellectual disabilities, while others need assistance with walking and do have intellectual disabilities. Cerebral palsy can also be accompanied by blindness, deafness, or epilepsy—a brain disorder that causes seizures.
Hearing impairment (or hearing loss) can occur when there is a problem in the hearing part of the brain, a problem with the nerves coming from the ears, or when there is a problem with one or more parts of the ear. A person living with a hearing impairment may be able to hear some sounds or nothing at all. Some people are born with a hearing impairment, while others experience hearing loss later in life. Hearing loss can also run in families.
Intellectual disability often results from a number of conditions that can develop before birth. Examples include fetal alcohol syndrome disorder, infections, and genetic and chromosomal conditions such as Down syndrome and fragile X syndrome. While intellectual disability usually develops before birth, it could develop any time before the age of 18. In these cases, intellectual disability may be caused by disease, injury, or a problem in the brain. A person living with intellectual disability may learn at a slower pace than others, function at a lower level than others in daily life, have trouble taking care of themselves, or have difficulty communicating their wants and needs.
Vision impairment is not common among children. When it does occur, more than half of all cases are in children living with other developmental disabilities. A person living with visual impairment does not see objects as clearly as usual. Unlike other types of vision problems that can be corrected with eye glasses or surgery, vision impairment means that a person’s eyesight cannot be corrected to a normal level.