
Developmental disabilities are conditions that affect the way a person grows. These are caused by problems in the genes, environment, or both. They can happen at any time during a child’s development and may have no known cause.
According to the United States Centers for Disease Control and Prevention, about one in six, or 17%, of children in the US aged between three and 17 have at least one form of developmental disability.
Here are seven developmental disabilities you should know about.
1. Autism
Autism is a complex disability affecting brain development, characterised by difficulties in social interaction, verbal and non-verbal communication, and repetitive behaviours.
People with autism spectrum disabilities can be highly intelligent. The American Academy of Pediatrics says 59.1% of participants with autism have an average or higher IQ, even if they face challenges in making friends, establishing relationships, learning new skills, and coping with change.
There are various types of autism, from mild Asperger’s syndrome to severe forms, including mental retardation.
Autistic children may have difficulty communicating and interacting with others. They may seem socially inept or reserved owing to their lack of understanding of social cues or rules for conversation. Speech patterns may be delayed or stilted, and eye contact may be minimal.
Many autistic children prefer to play alone rather than engage in group activities or share experiences with others. As such, behaviour, communication, speech, and educational therapy may be important tools for an autistic child.
2. Intellectual disability
Intellectual disability affects a person’s facilities when it comes to learning, reasoning, and solving problems. It is caused by issues in the brain, and can affect anyone at any age.
Intellectual disability is usually present at birth and can show up in those as old as 18 years, impacting a child’s emotional and intellectual development.
The term “intellectual disability” is often used interchangeably with “developmental disability”, although they are not the same thing; the former is part of the latter group.

3. Behavioural disabilities
Behavioural disabilities are mental health conditions that affect a child’s ability to behave in socially acceptable ways. Often caused by a combination of genetics and environment, these disabilities are often diagnosed during childhood and adolescence.
Examples include:
- attention deficit hyperactivity disability (ADHD);
- oppositional defiant disability (ODD);
- conduct disability;
- post-traumatic stress disability (PTSD);
- anxiety disabilities such as obsessive-compulsive disability (OCD).
Behavioural problems in children can be caused by trauma or abuse during childhood and an inherited tendency towards aggression or impulsivity. They may also be triggered by challenging environments, such as living with those who lack parenting skills or have substance-abuse issues.
4. Down Syndrome
Down Syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. It is the most common chromosomal disorder, and can cause various physical and cognitive challenges.
Data from the United Nations shows that between 3,000 and 5,000 children are born with this disorder worldwide every year.
People with Down Syndrome usually have characteristic facial features, such as a flat face and an upward slant in the eyes. They may also have developmental delays, intellectual disabilities, and difficulty with motor skills.
Despite these challenges, those with Down Syndrome can lead full and meaningful lives with the right support.
5. Cerebral palsy
Cerebral palsy causes impairment in physical movement, muscle tone, and motor skills. It develops in the womb or during early childhood, usually before age two. Estimates show that the prevalence of cerebral palsy is about 1-4 in 1,000 childbirths.
There are three main types: spastic, athetoid, and ataxic. Symptoms include:
- muscle tightness or weakness;
- stiff joints;
- problems with balance and coordination;
- difficulty swallowing or chewing food;
- frequent falls due to poor balance;
- slurred speech that may sound like baby talk (dysarthria); and
- drooling because of poor swallowing ability (dysphagia).
A variety of therapies play an important role in treating cerebral palsy, including physical, occupational, speech and language, and recreational therapy.

6. Foetal alcohol syndrome (FAS)
FAS is a spectrum of disabilities that can affect every organ system in the body. It is caused by alcohol exposure in the womb, and interferes with the development of a child’s brain and other organs.
Experts estimate that 2-5% of children in the US have FAS because of prenatal alcohol exposure.
The effects of FAS can range from mild to severe, but common symptoms include:
- small head size;
- shorter-than-average height for one’s age;
- problems with muscle tone;
- learning disabilities and intellectual impairment.
While there’s no cure for FAS, special education programmes can help affected children to cope with their conditions as they grow up.
7. Spina bifida
Spina bifida is a neural-tube defect that causes the spinal column to form incorrectly and leave a gap in the backbone. This can cause varying degrees of nerve damage, leading to motor-function impairment and other complications.
Symptoms vary depending on the extent of the damage. Paralysed limbs are common, as well as incontinence. Some people may also have problems related to fluid buildup in their brainstem, which can result in developmental delays and learning disabilities, depending on the severity.
Treatment for spina bifida depends on the type of condition a person has – occulta or meningitis. Surgery may be necessary if there’s too much pressure on the spinal cord, or if there’s an exposed part that needs protection so as not to cause further injury.
Otherwise, treatment involves physical-therapy sessions to improve mobility while reducing the pain caused by spasticity.
Dennis Relojo-Howell is the managing director of Psychreg and host of ‘The DRH Show’. Connect with him on Twitter @dennisr_howell.