There are two main features that can be seen in adults with intellectual disability. The first is a low general intelligence and the second is a problem with two or three categories of adaptive behaviors. There are a variety of characteristics that these adults can display, though for the most part, they struggle to understand and coexist with the people and the world around them. Once these characteristics have been identified, adults with intellectual disability can be given the support they need to live happy and productive lives.
One characteristic of adults with intellectual disability is a decreased intellectual ability. The intelligence quotient of these adults measures 69 or below, 31 points below average on a standard intelligence scale. Below this cut-off mark, the effects of the intellectual disability become considerably more pronounced as the intelligence quotient drops. Adults with intellectual disability may have trouble remembering, learning new things, communicating effectively, and understanding. There are many strategies for dealing with a low intelligence, and with practice, many adults can learn to use some of these effectively.
The other main characteristic of adults with intellectual disability is a problem with at least two different aspects of adaptive behavior. These adults may struggle to express themselves or to understand others, may lack social skills or may not be able to properly care for themselves without assistance. Adults with intellectual disability may have trouble expressing their thoughts, needs or wants, or they may not be able to understand what other people are trying to communicate to them. They may withdraw from social contact or react aggressively to others, often out of the frustration caused by struggling to understand. These adults may not be able to effectively feed themselves, bathe, or use the bathroom without assistance.
In some cases, an intellectual disability may be caused by a specific disorder. Adults with Down syndrome often have facial characteristics in common with other Down syndrome patients and health problems that affect the heart, sensory organs, or digestive system in addition to their cognitive impairments. Adults with intellectual disability who also have fragile X syndrome may have a variety of physiological characteristics, such as low muscle tone, soft skin, flexible joints, and flat feet. An intellectual disability that manifests later in life, such as one caused by an injury or illness, may have a variety of different characteristics depending on the part of the brain that is affected.