Developmental Disability

What counts as a developmental disability

In the US, the Developmental Disabilities Act defines a developmental disability as a severe, chronic condition that starts before age 22, is likely to continue indefinitely, and causes substantial limitations in major life activities such as self-care, language, learning, mobility or independent living. In everyday medical use, the term also covers milder neurodevelopmental conditions.

Developmental delay is a related but different term. It describes a young child who is behind in reaching milestones. Some children with delays catch up; others are later diagnosed with a lasting developmental disability.

Types of developmental disabilities

Many people have more than one. For example, epilepsy, intellectual disability and autism often occur together.

Early signs

Doctors compare a child's progress with developmental milestones. Possible signs:

• Movement: not holding the head up by 4 months, not sitting by 9 months, not walking by 18 months, stiff or floppy muscles, using one side much more than the other.
• Speech and language: no babbling by 12 months, no words by 16 months, no two-word phrases by 24 months, losing words.
• Social and emotional: little eye contact, not smiling at people, not pointing to share interest by 12 to 14 months, not responding to their name.
• Thinking and learning: difficulty following simple instructions, trouble with play, falling behind at school.
• Behavior: intense repetitive movements, extreme difficulty with change, severe tantrums beyond what is typical for age.

The CDC's free "Learn the Signs. Act Early." milestone checklists help parents track progress.

Causes and risk factors

Most developmental disabilities result from a mix of genetic and environmental factors acting before birth, around birth or in early childhood.

• Genetic and chromosomal conditions: Down syndrome, fragile X syndrome, Prader-Willi syndrome, cri-du-chat syndrome and many single-gene changes.
• Pregnancy factors: alcohol (causing fetal alcohol spectrum disorders), some medicines, smoking, infections such as cytomegalovirus, rubella, Zika and toxoplasmosis, and poorly controlled maternal diabetes or thyroid disease.
• Birth complications: premature birth, very low birth weight, and lack of oxygen around delivery.
• After birth: brain infections such as meningitis, head injury, severe jaundice, lead exposure, severe malnutrition and untreated congenital hypothyroidism.

Vaccines do not cause autism or other developmental disabilities; this has been studied extensively.

Diagnosis

1. Surveillance at every well-child visit: the doctor asks about milestones and any concerns.
2. Standardized screening: the American Academy of Pediatrics recommends developmental screening at 9, 18 and 30 months, and autism screening at 18 and 24 months.
3. Full evaluation: if screening raises concerns, a developmental pediatrician, child neurologist, psychologist, or speech, occupational and physical therapists assess the child in detail.
4. Medical tests: hearing and vision tests for every child with speech or developmental delay; genetic tests such as chromosomal microarray and fragile X testing; and sometimes brain MRI, EEG for seizures, metabolic tests, thyroid tests and blood lead levels.

You do not need to wait for a diagnosis to start services. In the US, children under 3 can be referred directly to the state's early intervention program, and older children can be evaluated through the public school system.

Treatment and support

There is no cure for most developmental disabilities, but the right support improves skills, independence and quality of life.

• Early intervention (birth to 3): speech, occupational and physical therapy, often at home.
• Special education (age 3 to 21): an Individualized Education Program (IEP) or 504 plan sets out support at school.
• Behavioral therapies: such as applied behavior analysis and parent training programs for autism and challenging behavior.
• Medicines: for related conditions such as ADHD, epilepsy, sleep problems, spasticity or anxiety. There is no medicine for the core disability itself.
• Assistive technology: communication devices, mobility aids, hearing aids.
• Medical care: regular checks for hearing, vision, dental health, nutrition, growth and associated conditions such as heart defects in Down syndrome.
• Transition planning: from about age 14, planning for adult health care, employment, housing and decision-making support.

Living with a developmental disability

Many people with developmental disabilities attend school, work, live independently or with support, and have full social lives. Outcomes vary with the type and severity of the disability and the support available. Families benefit from respite care, parent support groups, and help navigating benefits such as Medicaid waivers and Supplemental Security Income.

People with developmental disabilities have higher rates of some health problems, including epilepsy, obesity, dental disease, and mental health conditions, and may have difficulty reporting symptoms. Changes in behavior can be the first sign of pain or illness.

Frequently asked questions

What is considered a developmental disability?

A developmental disability is a lifelong condition that starts before adulthood and limits areas such as learning, language, movement, behavior or self-care. Common examples include autism, intellectual disability, cerebral palsy, ADHD, learning disorders, and hearing or vision loss present from early life.

What is the difference between developmental delay and developmental disability?

Developmental delay means a young child is behind on milestones. It describes the present, and some children catch up. Developmental disability means a lasting condition, such as autism or intellectual disability, that will continue into adulthood.

What are the most common developmental disabilities?

ADHD, learning disabilities and autism are the most common in the US, followed by intellectual disability, cerebral palsy, and hearing and vision loss. Many children have more than one condition at the same time.

Can developmental disabilities be prevented?

Some can. Avoiding alcohol in pregnancy, vaccination against rubella, prenatal care, folic acid before and during early pregnancy, newborn screening, and preventing lead exposure and head injuries all reduce risk. Many genetic causes cannot be prevented.

At what age are developmental disabilities diagnosed?

It depends on the condition. Cerebral palsy and Down syndrome are often recognized in infancy, autism is reliably diagnosed from about age 2, and learning disabilities and ADHD usually become clear at school age. Early screening helps catch them sooner.