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Intellectual Disability Assessment

Intellectual Disability Assessment

What is Intellectual Disability?

Intellectual disability involves problems with general mental abilities that affect functioning in two areas:

1.Intellectual functioning (such as learning, problem-solving, judgment).
2.Adaptive functioning (activities of daily life such as communication and independent living).

Additionally, the intellectual and adaptive deficit begins early in the developmental period.

Prevalence of Intellectual Disability

Intellectual disability affects about 1% of the population, and of those, about 85% have a mild intellectual disability. Males are more likely than females to be diagnosed with intellectual disability.

Diagnosing Intellectual Disability

Intellectual disability is identified by problems in both intellectual and adaptive functioning.

Intellectual functioning is measured with individually administered and psychometrically valid, comprehensive, culturally appropriate, psychometrically sound intelligence tests. While a specific full-scale IQ test score is no longer required for diagnosis, standardized testing is used to diagnose the condition. A full-scale IQ score of around 70 to 75 indicates a significant limitation in intellectual functioning. However, the IQ score must be interpreted in the context of the person’s difficulties in general mental abilities. Moreover, scores on subtests can vary considerably, so the full-scale IQ score may not accurately reflect overall intellectual functioning. Therefore, clinical judgment is needed in interpreting the results of IQ tests.

Three areas of adaptive functioning are considered:

  1. Conceptual – language, reading, writing, math, reasoning, knowledge, memory.

  2. Social – empathy, social judgment, communication skills, the ability to follow the rules and the ability to make and keep friendships.

  3. Practical – independence in areas such as personal care, job responsibilities, managing money, recreation, and organizing school and work tasks.

Adaptive functioning is assessed through standardized measures with the individual and interviews with others, such as family members, teachers and caregivers.

The severity of Intellectual Disability

Intellectual disability is identified as mild (most people with intellectual disability are in this category), moderate or severe. The symptoms of intellectual disability begin during childhood. Delays in language or motor skills may be seen by age two. However, mild levels of intellectual disability may not be identified until school-age when a child has difficulty with academics.


There are many different causes of intellectual disability. It can be associated with a genetic syndrome, such as Down syndrome or Fragile X syndrome. It may develop following an illness such as meningitis, whooping cough or measles; it may result from head trauma during childhood or may result from exposure to toxins such as lead or mercury. Other factors contributing to intellectual disability include brain malformation, maternal disease and environmental influences (alcohol, drugs or other toxins). Various labour- and delivery-related events, infection during pregnancy and problems at birth, such as not getting enough oxygen, can also contribute.


Intellectual disability is a life-long condition. However, early and ongoing intervention may improve functioning and enable the person to thrive throughout their lifetime.

Once a diagnosis is made, help for individuals with an intellectual disability is focused on the individual’s strengths and needs and the support they need to function at home, in school/work and in the community.

Services for people with intellectual disabilities and their families can provide support to allow full inclusion in the community. Many different types of support and services can help, such as:

  • Early intervention (infants and toddlers).

  • Special education.

  • Family support (for example, respite care support groups for families).

  • Transition services from childhood to adulthood.

  • Vocational programs.

  • Day programs for adults.

  • Housing and residential options.

  • Case management.

Related and Co-occurring Conditions

Some mental health, neurodevelopmental, medical and physical conditions frequently co-occur in individuals with intellectual disability, including autism spectrum disorder, cerebral palsy, epilepsy, attention-deficit hyperactivity disorder, impulse control disorder, and depression and anxiety disorders. Identifying and diagnosing co-occurring conditions can be challenging, for example recognizing depression in an individual with limited verbal ability. An accurate diagnosis and treatment are essential for a healthy and fulfilling life for any individual.

Intellectual Disability assessment services at The Manor Clinic

Our experienced psychologists provide intellectual disability assessments and use specialized assessment tests. Based on these tests, we produce a report shared with the referring professional and the client. The report includes a cognitive profile, detailed recommendations, objective information about the patient’s functioning, and specific issues that may be helped with therapeutic intervention.

Please get in touch with Manor Clinic for further information about the intellectual disability assessments that we provide:


If you want to book an assesment

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