Quick Guide to Intellectual Developmental Disorder

Intellectual developmental disorder (IDD), also known as intellectual disability, means that a child has challenges with thinking and learning in several areas. This can include difficulties with reasoning, solving problems, planning, understanding complex ideas, making good decisions, and learning in school or from experiences. These challenges can make it harder for children to take care of themselves, communicate, join in social activities, and be independent at home or in the community. They might seem to be acting out, but it also may be that they don’t understand what behavior is appropriate.

Intellectual developmental disorder is a relatively new term used to describe individuals with significant limitations in intellectual functioning and adaptive behavior. In the past, these same symptoms were called “mental retardation.” 

The main symptom of IDD is difficulty with thinking and learning. Specific symptoms can include:  

• Delayed milestones such as sitting, crawling, walking, and talking
• Difficulty understanding simple instructions or concepts
• Finding it hard to remember things, solve problems, or learn and apply new information
• Struggling to keep up at school 

• Challenges in understanding and following social rules
• Trouble making friends and interacting with peers
• Problems with personal care and managing daily activities independently

Kids with IDD also have difficulties in at least one of the following areas:

• Practical Skills: This includes how well they take care of themselves and handle everyday daily living skills. They may struggle with things like personal care, managing money, keeping up with school or work tasks, and organizing their day-to-day activities.
• Conceptual Skills: They might find it hard to remember things, use language, read, write, do math, solve problems, and make good decisions in new situations.
• Social Skills: They may have trouble understanding other people’s feelings and thoughts, showing empathy, communicating with others, making friends, and using good social judgment.

Intellectual development disorder starts during a child’s development, and is usually identified in infancy, childhood, or adolescence. The age when it starts and the specific signs can vary depending on the cause and severity.

IDD can be caused by a variety of factors, which can be grouped into genetic, environmental, and other medical conditions.

Genetic causes:

• Chromosomal abnormalities such as Down syndrome and Fragile X syndrome
• Inherited metabolic disorders like phenylketonuria (PKU) and Tay-Sachs disease

Environmental causes:

• Prenatal exposure to alcohol, drugs, or infections (e.g., rubella) during pregnancy
• Poor nutrition during pregnancy
• Exposure to lead or other environmental toxins

Perinatal and neonatal causes:

• Birth complications such as lack of oxygen (hypoxia) during birth
• Being born significantly early or with a very low birth weight
• Severe infections shortly after birth (e.g., meningitis)

Other medical conditions:

• Traumatic brain injuries at a young age
• Severe malnutrition during early childhood
• Chronic illnesses such as seizures or untreated hypothyroidism

While IDD is a lifelong disability, a number of supports and services can help children learn the skills they need and improve their quality of life. These include special education services, therapeutic supports, social skills training, and life skills training. Family support through parent training, counseling, and support groups can also be beneficial. These supports can help individuals with intellectual developmental disorder develop important skills, achieve greater independence, and participate more fully in their communities.