Developmental disability is a diverse group of chronic conditions, comprising mental or physical impairments that arise before adulthood. Developmental disabilities cause individuals living with them many difficulties in certain areas of life, especially in "language, mobility, learning, self-help, and independent living". Developmental disabilities can be detected early on and persist throughout an individual's lifespan. Developmental disability that affects all areas of a child's development is sometimes referred to as global developmental delay.
The most common developmental disabilities are:Motor disorders, and learning difficulties such as dyslexia, Tourette's syndrome, dyspraxia, dysgraphia, Irlen syndrome, dyscalculia, and Nonverbal learning disorder. Autism and Asperger syndrome are a series of conditions called autistic spectrum disorders (formerly called Pervasive developmental disorders) that cause difficulties in communications. Autistic spectrum disorders affect speech, understanding body language, social interactions, difficulty in understanding others in areas such as sarcasm and other's feelings, and causes repetitive behaviors known as stimming. Down syndrome is a genetic condition in which people are born with an extra copy of chromosome 21. This extra copy affects the development of the body and brain, causing a range of physical and mental impairments for the individual. Fragile X syndrome, most frequent among males, is thought to cause autism and intellectual disability. Fetal alcohol spectrum disorders are a group of conditions caused prior to birth that can occur in a person whose mother drank alcohol during pregnancy. Cerebral palsy is a group of disorders that affect a person's ability to move and maintain balance and posture. They are the most common motor disability in childhood. Intellectual disability, also (sometimes proscriptively) previously (and no longer referred to) as "mental retardation", is defined as assessed to have an IQ below 70, along with limitations in adaptive functioning and onset before the age of 18 years. Attention deficit hyperactivity disorder, often called ADHD, is a neurodevelopmental disorder characterized by executive dysfunction. It has effects on attention span, cognition, self-control, and emotional regulation.