can iq decrease with age

Introduction

The relationship between age and IQ has been a subject of extensive research. Various studies have explored how IQ changes over the lifespan, considering factors such as heritability, environmental influences, and specific conditions like brain irradiation and genetic syndromes. This synthesis aims to present a cohesive understanding of whether IQ decreases with age based on the provided research papers.

Key Insights

Heritability and Stability of IQ with Age:
- The heritability of IQ increases with age, reaching an asymptote at about 0.80 by 18-20 years and remaining stable into adulthood. Shared environmental influences decrease significantly by this age.
IQ and Aging in Normal Populations:
- Older adults (60-79 years) show increased variability in timing tasks, but their average performance remains accurate, suggesting that while some cognitive processes may slow, overall IQ does not necessarily decline significantly with age.
Impact of Whole-Brain Irradiation:
- IQ decline is observed in children who undergo whole-brain irradiation, with higher doses and younger age at treatment leading to more significant declines. Older children show less decline compared to younger ones.
Williams Syndrome and IQ:
- In individuals with Williams syndrome, overall IQ remains stable with age, although Performance IQ may increase. This suggests that specific cognitive abilities can improve even if overall IQ does not decline.
Mentally Retarded Populations:
- In institutionalized mentally retarded individuals, Full Scale IQ does not decrease with age. There are slight increments in IQ, particularly in Performance IQ, challenging the notion that IQ declines in this population .
EEG Characteristics and IQ:
- In older adults, a decrease in IQ correlates with age-related changes in EEG characteristics, such as a decrease in individual alpha peak frequency. However, high intelligence in older adults is associated with specific EEG patterns, indicating that while some cognitive decline may occur, it is not uniform across all individuals.

Conclusion

The research indicates that while certain cognitive abilities may decline with age, overall IQ does not necessarily decrease uniformly. Heritability plays a significant role in maintaining IQ stability into adulthood. Specific conditions, such as whole-brain irradiation in children, can lead to IQ decline, but this is influenced by factors like dose and age at treatment. In populations with genetic conditions like Williams syndrome or institutionalized mentally retarded individuals, IQ tends to remain stable or even show slight improvements in certain areas. Therefore, the relationship between age and IQ is complex and influenced by various factors, but a general decline in IQ with age is not universally supported by the evidence.

Can iq decrease with age

Summary

Introduction

Key Insights

Conclusion

Sources and full results

The Wilson Effect: The Increase in Heritability of IQ With Age

The heritability of IQ increases with age, reaching an asymptote of 0.80 at 18-20 years of age and continuing at that level well into adulthood, while shared environmental influence decreases across age.

Age and IQ effects on stimulus and response timing

Increased age and decreasing IQ tend to increase variability in judgments of duration, but overall accuracy in timing tasks remains generally consistent across groups.

Whole-brain irradiation and decline in intelligence: the influence of dose and age on IQ score.

Whole-brain irradiation dose and age at time of irradiation impact IQ decline in children, with older age resulting in less decline in IQ score.

The relationship between age and IQ in adults with Williams syndrome.

Adults with Williams syndrome show a stable overall IQ, but Performance IQ increases with age, suggesting that overall IQ may remain stable.

Aging and IQ Change in Institutionalized Mentally Retarded

Full Scale IQ does not decrease with age in institutionalized mentally retarded individuals, but Performance IQ shows larger and more consistent increments.

IQ decline in mentally retarded adults: a matter of fact or methodological flaw.

Mentally retarded adults show no decline in intelligence with age, but rather regular increases in performance scores when studied semi-longitudally.

[Age Effect on Relationship Between Intelligence and EEG Characteristics].

High intelligence in younger individuals is predicted by high alpha3 power and low beta1 power, while in elder individuals, increased alpha peak frequency and decreased theta/beta1 power ratio are associated with high intelligence.

Aging trajectories of fluid intelligence in late life: The influence of age, practice and childhood IQ on Raven's Progressive Matrices

Fluid intelligence in late life ages with practice and decline, with practice being the greatest influence after the first repeat testing.

Developmental implications of changing trajectories of IQ in males with fragile X syndrome.

Males with fragile X syndrome show a decline in IQ scores, with the most marked declines seen during early puberty, suggesting a slowing of intellectual development associated with puberty onset.

Effects of aging and IQ on item and associative memory.

Aging and IQ have complex interactions on item and associative memory, with IQ affecting drift rate and recall performance, while age has small effects on boundary separation and nondecision time.

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