IQ scores are stable over a person's lifetime.

Is it true that IQ scores are stable over a person's lifetime?

Partly. The retrieved items only partially address the claim: a textbook and a popular book assert that IQ scores are stable over a lifetime, while a clinical study finds stable global IQ only in youth with neurodevelopmental disabilities, and a forum question plus a diabetes study note instability or lack of demonstrating evidence. No item provides a full lifetime longitudinal dataset settling the claim.

Verdict: CONTESTED PARTIAL · 3 sources for, 2 against · Last checked 16 Oct 2026

The private library was unavailable for some searches in this check. Missing library results are not evidence against the claim.

Stephenson, K. G., Norris, M., Kim, S. Y., Russell, N. C. C., Levine, A., Murphy, C., Youngstrom, E. A., & Butter, E. M. (2026). Long-Term Stability of IQ Scores for Children With Neurodevelopmental Disabilities: Stable Global IQ But Unstable Index, Subtest, and Profile IQ Scores. doi.org. https://doi.org/10.1007/s10803-026-07352-x

IQ Test stability longitudinal study. (n.d.). cogsci.stackexchange.com. https://cogsci.stackexchange.com/questions/21690

Matheson, D. (2014). An Introduction to the Study of Education. books.google.com. http://books.google.com/books?id=jKKsAgAAQBAJ&dq=IQ+scores+are+stable+over+a+person%27s+lifetime.&hl=&as_pt=BOOKS&source=gbs_api

Jeffries, S. (2025). A Short History of Stupidity. play.google.com. https://play.google.com/store/books/details?id=q-p_EQAAQBAJ&source=gbs_api

Severe hypoglycaemia and late‐life cognitive ability in older people with Type 2 diabetes: the Edinburgh Type 2 Diabetes Study. (n.d.). cir.nii.ac.jp. https://doi.org/10.1111/j.1464-5491.2011.03505.x