Tags: IDD; intellectual disabilities; life skills; mild IDD; moderate IDD; severe IDD; profound IDD

People with intellectual developmental disorders (IDD) experience limitations in both intellectual functioning and adaptive behaviors (such as social skills or life skills). For more information on intellectual development disorders, you can view our overview here.

Types of IDD Diagnoses

While there are clear diagnostic criteria for IDD,  it presents itself differently in each person. Intellectual disabilities are divided into four subtypes: mild, moderate, severe, and profound.

Below, we'll explore the levels of intellectual disabilities, how they’re diagnosed, and how they present themselves.

1. Mild Intellectual Disability

Mild intellectual disabilities (IDD) represent the most common level of IDD, encompassing individuals who often display subtle developmental delays.

Common Characteristics:

• IQ Range: 50-70
• Percentage of IDD Population: About 85%

Academic Skills:

• Can achieve elementary-level reading and math skills
• Struggle with subjects requiring abstract thinking, such as math and language

Thinking Style:

• Concrete interpretation of information
• Difficulty understanding sarcasm and abstract social cues

Those with mild IDD may need extra guidance navigating complex tasks, such as making legal decisions or assessing risk. Despite these challenges, they can often live relatively independently with appropriate support.

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2. Moderate Intellectual Disability

Moderate intellectual disabilities (IDD) are characterized by significant developmental delays, typically identified during early childhood.

Common Characteristics:

• IQ Range: 35-49
• Percentage of IDD Population: About 10%
• Diagnosis Age: Typically diagnosed between ages 3 and 5 due to noticeable delays in language skills

Academic Skills:

• Basic literacy and numeracy skills with appropriate support
• Struggle with more advanced academic subjects and abstract concepts

People with moderate IDD often require ongoing support with daily activities, such as personal care, social skills, and safety practices. With the right support and skills training, they can attain relative independence in essential self-care and daily living tasks, including maintaining personal hygiene and developing successful relationships. 

For more information on how you can help individuals with IDD acquire skills, view our article here.

3. Severe Intellectual Disability

Individuals with severe intellectual disability face substantial challenges in communication and daily living skills, requiring consistent, hands-on support from caregivers.

Common Characteristics:

• IQ Range: 20-35
• Percentage of IDD Population: About 4%
• Diagnosis Age: Typically identified by age 3 or earlier due to developmental delays

Communication Skills:

• Understands most basic communication
• Limited ability to express themselves verbally
• May use single words, short phrases, or gestures

Daily Living Skills:

• Needs ongoing support for basic self-care and daily routines
• Assistance from a dedicated caregiver

Those with severe IDD require ongoing support in daily life activities and often need a dedicated caregiver to assist with basic self-care and daily routines.

4. Profound Intellectual Disability

Profound intellectual disabilities (IDD) represent the most severe level of IDD, with individuals experiencing significant developmental delays and requiring intensive care. 

Common Characteristics:

• IQ Range: Below 20
• Percentage of IDD Population: About 1.5%
• Co-occurring Conditions: Nearly all individuals have co-occurring medical conditions or disabilities
• Developmental Delays: Significant delays in all areas

Communication Skills:

• Nonverbal communication
• Uses gestures and facial expressions to convey needs

Daily Living Skills:

• Require round-the-clock care
• High support needs for basic self-care and daily routines

While they might struggle to participate in social activities, those with profound IDD still enjoy the company of people around them and benefit from spending quality time with their loved ones. Due to the nature of their needs, they often require round-the-clock care. 

Most people with intellectual disability will need some form of support throughout their lives. However, it’s important to remember that the vast majority of children with IDD fall within the “mild” category, and with some support can live relatively independent, happy lives. 

Understanding intellectual and developmental disabilities requires a compassionate and informed approach. From early diagnosis to tailored support, individuals with IDD can achieve meaningful milestones and lead fulfilling lives. By empowering them and supporting their families, we create a more inclusive society where everyone can thrive.

Need personalized guidance or resources for supporting individuals with IDD? Contact us today to learn how we can help!

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