Does IQ change with age?
Your position relative to others of your age tends to be fairly stable, though not fixed. Abilities themselves do change over life.
What long studies found
The Lothian Birth Cohort studies in Scotland tested people at age 11 and again in old age. Correlations with the age 11 score were .67 at age 70, .66 at 79 and .51 at 87. A later study found .54 at age 90, or .67 after a statistical correction for who remained in the study.
Stable does not mean fixed
These numbers show a strong link and also plenty of room for change. The authors estimate that childhood scores account for roughly 26 to 44% of the differences at those later ages, at minimum.
Why IQ can stay the same while abilities change
IQ scores compare you with people of your own age. If your abilities change at about the same pace as theirs, your IQ stays about the same, even though your raw performance has changed.
Limits of this evidence
These studies followed particular groups of people born in Scotland in 1921 and 1936, and those who stayed in the study into old age are not typical of everyone.
Sources
- Gow et al. (2011), Stability and change in intelligence from age 11 to ages 70, 79, and 87: The Lothian Birth Cohorts. Psychology and Aging
- Deary, Pattie & Starr (2013), The stability of intelligence from age 11 to age 90 years. Psychological Science
Last checked: 2026-11-03
A summary of published research, not medical, career or psychological advice. A correlation describes groups, not any one person. This text has not yet been reviewed by a psychologist.