NTG issues statement on IQ use

In response to the Supreme Court’s consideration of IQ as a determinant in death penalty cases involving adults with intellectual disability, the NTG issued a statement urging rejection of IQ-based criteria and adoption of a comprehensive, clinically grounded definition of intellectual disability. The statement also cautioned against relying solely on IQ scores when determining service eligibility for adults with intellectual disability and dementia.

Declaratory Statement on the Misuse of IQ Scores and the Imperative for Accurate Dementia Diagnosis in Adults with Intellectual Disability

The National Task Group on Intellectual Disabilities and Dementia Practices (NTG) expresses deep concern regarding recent developments that highlight the continued misuse of IQ scores as sole determinants of intellectual disability. As long recognized in the scientific and clinical communities, IQ test results are influenced by numerous factors—including the individual’s emotional state, testing environment, cultural and linguistic background, examiner expertise, instrument selection, and day-to-day fluctuations in functioning. Reliance on a single score, or even multiple scores taken out of developmental and adaptive context, is inconsistent with best practice, scientifically unsound, and risks profound harm.

The case now pending before the United States Supreme Court underscores these dangers starkly: the possibility that a narrowly interpreted IQ score could be used to justify the imposition of the death penalty. Such an outcome would not only contradict decades of clinical science but would profoundly undermine human rights. No individual’s life, liberty, or access to essential supports should ever hinge on a single psychometric number.

This concern has broader implications for aging adults with intellectual disability. In the context of dementia—particularly Alzheimer’s disease in adults with Down syndrome—diagnostic complexity is the rule, not the exception. The field is still evolving toward more refined criteria, and assessments must consider lifelong developmental profiles, baseline variation, medical comorbidities, and the subtleties of age-related change. Yet states may be tempted to misuse diagnostic uncertainty as a basis to restrict or deny dementia-related services. Such actions would place vulnerable adults at risk and run counter to the ethical and clinical standards that guide person-centered care.

Therefore, the NTG affirms the following principles:

1. IQ scores must never be used in isolation to determine intellectual disability status, service eligibility, or legal culpability.

2. Dementia diagnoses in adults with intellectual disability require comprehensive, individualized, and context-sensitive evaluation, including longitudinal comparison, medical rule-outs, and input from informed caregivers.

3. Service systems and eligibility frameworks must recognize the diagnostic realities of dementia in people with lifelong disabilities and avoid reductive criteria that permit the denial of needed supports.

4. Clinical decision-making should reflect contemporary science, not simplistic reliance on psychometric thresholds.

Call to Action

The NTG urges federal and state policymakers, clinical organizations, and disability advocates to:

• Reject policies that rely solely on IQ scores for determining intellectual disability or access to services.

• Adopt and promote evidence-informed guidelines for dementia diagnosis in adults with intellectual disability, including the use of baseline assessments and multi-method evaluation.

• Ensure that no adult with intellectual disability is denied dementia-related services due to diagnostic ambiguity, outdated criteria, or misinterpretation of lifelong cognitive profiles.

• Engage in cross-sector dialogue—linking disability services, aging networks, and health systems—to safeguard equitable access to dementia care.

As diagnostic science evolves, ethical responsibility demands that we protect the rights, dignity, and well-being of people with intellectual disability. Their lives must never be reduced to a number. Their access to care must never depend on diagnostic shortcuts. And their support needs must be recognized, respected, and met across the lifespan.