The Characteristics of Intellectual Disability

Intelligence refers to a person's ability to understand, communicate, reason, acquire and apply thought. Intellectual disability refers to a person's impaired cognitive functioning ability. This condition occurs for several reasons, including genetic disorders such as Down syndrome, pregnancy problems such as Fetal Alcohol Spectrum Disorder, serious health problems such as meningitis or measles or birth complications. There are three characteristics of intellectual disability. A person must display all three characteristics before a diagnosis of intellectual disability is confirmed.

Borderline or Mild IQ

• A person's intellectual functioning abilities are assessed by intelligence tests which determine the individuals Intelligence Quota, or IQ. The levels of intelligence, which are determined by an IQ test, fall into four categories: borderline or mild, moderate, severe and profound. These levels are based on assessment results and are clinical definitions of a person's level of intellectual functioning. IQ's are arbitrary and do not measure a person's strengths, wants or lifestyle. An IQ which falls at or below 70 is two standard deviations below the average, and considered borderline or mild intelligence. Possessing a borderline or mild IQ is a characteristic of intellectual disability.

Deficits in Adaptive Behavior

• Adaptive behavior is a person's ability to adjust their behavior to different types of behaviors or situations, often referring to personal or social occurrences. The term "deficits in adaptive behavior" refers to a person's everyday functioning skills, including communication and personal care abilities. A person who is less independent and capable of managing everyday tasks displays this characteristic of intellectual disability. Adaptive behavior tests assess if a person needs additional education, support and training to be able to function in an independent manner as compared to others of the same culture and age.

Characteristics are Evident in the Developmental Period

• A person must show both a borderline or mild IQ and a deficit in adaptive behavior in the developmental period in order to be diagnosed with an intellectual disability. The developmental period is defined as the time between birth and age 18. Young children who display the characteristics of intellectual disability may take longer to walk and speak. School-aged children may struggle in school and display memory and attention problems. The developmental delays these children exhibit are generally noticeable at a young age, especially in a setting which includes several children in the same peer group.