Does a person's iq change

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Research Analysis by Consensus

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Changes in IQ Over Time: Insights from Recent Research

Stability and Variability of IQ in Adolescence

Teenage Brain Development and IQ Fluctuations

Research indicates that while IQ is generally considered stable, it can exhibit significant fluctuations during the teenage years. A study utilizing neuroimaging techniques found that both verbal and non-verbal IQ can rise or fall during adolescence. These changes are closely linked to alterations in brain structure, specifically grey matter in regions associated with speech and finger movements. This suggests that an individual's intellectual capacity relative to their peers can increase or decrease during these formative years.

The Flynn Effect and Age-Related Variations

The Flynn Effect, which describes generational increases in IQ scores, does not apply uniformly across all ages and ability levels. A large-scale study of over 10,000 US adolescents found that while younger teens (age 13) showed an increase in IQ, older teens (age 18) exhibited a decrease. Additionally, those with lower initial IQs experienced a decline, whereas those with higher IQs saw an increase. This highlights the complexity and variability of IQ changes across different age groups and ability levels.

IQ Changes in Special Populations

Schizophrenia and IQ Trajectories

In individuals with schizophrenia, IQ tends to be lower at baseline compared to healthy controls. However, longitudinal studies show that IQ can increase over time in both patients and their siblings, albeit at different rates. Siblings of schizophrenia patients showed a more pronounced increase in IQ compared to the patients and healthy controls. Another meta-analysis confirmed that while schizophrenia patients have a lower baseline IQ, their IQ increases at a slower rate compared to healthy individuals. This suggests that while cognitive deficits are a feature of schizophrenia, there is still potential for cognitive improvement over time.

Impact of Long-Term Psychotherapy

Long-term psychotherapy has been shown to positively influence IQ. Studies have reported that IQ tends to increase during and after extended periods of psychotherapy. This increase is associated with various personality changes, indicating that supportive and strengthening treatments can contribute to cognitive improvements.

Biological and Environmental Influences on IQ

Brain Structure and Intelligence

There is a significant positive association between brain volume and IQ, although this relationship has been overestimated in some literature. Modern imaging techniques have shown that larger brain volumes are generally associated with higher IQs across different age groups and sexes. Additionally, changes in cortical thickness and surface area over time are related to intelligence. More intelligent children tend to have a thinner cortex at age 10, which thins faster over time, while cortical surface area expands and then decreases at a higher rate in more intelligent individuals.

Heritability and Environmental Factors

The heritability of IQ has been a topic of extensive research. Studies suggest that maternal effects, such as the womb environment, play a significant role in the covariance of IQ among relatives, particularly twins. This challenges the traditional view that shared family environments are the primary contributors to IQ similarities. Furthermore, developmental changes in IQ are influenced by environmental factors, with significant fluctuations observed in childhood and adolescence.

Conclusion

In summary, while IQ is often viewed as a stable measure of cognitive ability, research shows that it can change significantly during adolescence and in response to various factors such as brain development, mental health conditions, and environmental influences. These findings underscore the dynamic nature of intelligence and the potential for cognitive growth and decline throughout different stages of life.