Iq and age correlation
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Correlation Between IQ and Age: A Comprehensive Analysis
Premorbid IQ and Mortality Risk
Research has consistently shown that higher IQ scores in early life are associated with lower mortality rates in later years. Studies that followed individuals from childhood or early adulthood into middle and late adulthood found a clear inverse relationship between IQ and mortality risk. This means that individuals with higher IQs tend to live longer . The association appears robust, not significantly influenced by reverse causality or selection bias, and is partially mediated by adult socioeconomic status.
IQ and Age in Childhood
The relationship between IQ and age during childhood has been explored in various studies. One study found that the negative correlation between mean IQ and age reported in a sample of southeastern Negro children was likely due to sampling methods rather than a true developmental trend. Another study examining the WISC-R subtests across different demographics found that the relationship between age and intelligence test performance is relatively constant across race and sex, although Black males showed smaller incremental changes in Full Scale IQ with age compared to other groups.
IQ as a Predictor of Adult Outcomes
Childhood IQ has been shown to predict adult educational and occupational status. By the second grade, the predictive correlations of childhood IQ with these adult outcomes approach those obtained with contemporaneous adult IQs, especially for occupational status . However, these correlations are not high enough for practical long-term predictions for individual children .
Brain Volume and IQ Across Ages
A meta-analysis of studies examining the relationship between brain volume and IQ found significant positive associations that generalize across different ages, IQ domains, and sexes. However, the strength of this association has been overestimated in the literature, and the reported effects have been declining over time. This suggests that while brain volume is related to IQ, it should not be considered a direct proxy for intelligence differences.
IQ and Everyday Functioning in Intellectual Disabilities
For individuals with mild or borderline intellectual disabilities, IQ is a poor predictor of general aspects of everyday functioning. No significant correlations were found between IQ and measures of self-rated ability, participation, and general well-being. This indicates that other factors beyond IQ play a significant role in everyday functioning for this population.
Health and IQ in Midlife
In a cohort of Swedish women, intelligence measured in adolescence showed limited associations with health status and behaviors at age 43. While lower IQ was associated with higher risks of obesity and high systolic blood pressure, no significant correlations were found with other health indicators after adjusting for educational level. This suggests that the impact of IQ on health behaviors and outcomes may be mediated by other factors such as education.
Conclusion
The correlation between IQ and age reveals complex interactions influenced by various factors including socioeconomic status, health behaviors, and methodological considerations. While higher early-life IQ is associated with lower mortality and better adult outcomes, the relationship between IQ and everyday functioning, especially in individuals with intellectual disabilities, is less straightforward. Further research is needed to explore these dynamics across different populations and over the lifespan.
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