There are many definitions used to explain, define and determine a mental or cognitive disability. Cognitive disability is described by the presence of a sub-average general intellectual functioning associated with or resulting in impairments in adaptive behavior. The onset occurs before the age of 18. IQ scores classify the level of cognitive disability. They range in scope from mild to profound. A cognitive disability should not be confused with a psychiatric disability or mental illness.

Examples of mental or cognitive disabilities include:
• Autism
• Down Syndrome
• Mental Retardation

A person with a cognitive disability may:
• have difficulty speaking and understanding what is communicated.
• have a physical disability.
• have difficulty learning.
• display inappropriate behavior.
• be unable to live independently.
• have difficulty participating in group settings, and expressing needs.

Causes of cognitive disabilities are many. They include an abnormal number of chromosomes, gene defects, maternal infections, head trauma, birth injury, and deprived normal development and growth experiences. Intellectual disability is twice as common in males as in females.