Does iq diminish with age
Pro Research Analysisby 
Searched over 200M research papers
Consensus Meter
Does IQ Diminish with Age?
Age-Related Decline in Cognitive Abilities
Research consistently shows that cognitive abilities, including IQ, tend to decline with age. This decline is more pronounced in certain types of intelligence. For instance, performance IQ, which involves problem-solving and processing speed, tends to decline earlier and more rapidly than verbal IQ, which involves knowledge and language skills. This pattern is observed in both the general population and individuals with intellectual disabilities, although the rate and extent of decline can vary.
Impact of IQ on Cognitive Decline
Higher IQ appears to provide some protection against cognitive decline, a concept known as the cognitive reserve hypothesis. Individuals with higher IQs tend to experience a later onset of terminal decline (TD) in cognitive abilities. However, once the decline begins, it tends to be steeper compared to those with lower IQs. This suggests that while a higher IQ can delay the onset of cognitive decline, it does not necessarily prevent it.
Role of Physical Health
Physical health significantly mediates the effect of age on fluid intelligence, which involves reasoning and problem-solving abilities. Studies indicate that the decline in fluid intelligence with age is fully mediated by physical health, particularly diseases of the circulatory and nervous systems. This implies that maintaining good physical health can mitigate some of the age-related declines in cognitive abilities.
Stability of IQ Over the Lifespan
Longitudinal studies, such as the Scottish Mental Surveys, have shown that IQ scores can remain relatively stable from childhood into old age. However, the stability of these scores can be influenced by various factors, including health and socioeconomic status. Higher childhood IQ is associated with better health outcomes and lower mortality rates in later life, suggesting a long-term benefit of higher cognitive abilities.
Differential Effects on Memory and Processing Speed
Age and IQ have different effects on various cognitive tasks. For example, older adults tend to show increased variability in timing tasks, but their average performance can remain accurate. In memory tasks, higher IQ is associated with better performance, although the oldest participants show significant declines in certain types of memory, such as associative recognition and cued recall. This indicates that while IQ can influence cognitive performance, age-related declines are inevitable in some areas.
Conclusion
In summary, while IQ does tend to diminish with age, the extent and rate of decline can vary based on several factors, including initial IQ levels, physical health, and the type of cognitive ability being measured. Higher IQ can delay the onset of cognitive decline, but it does not prevent it entirely. Maintaining good physical health is crucial in mitigating some of the age-related declines in cognitive abilities.
Sources and full results
Most relevant research papers on this topic