does intelligence decline with age

Introduction

The relationship between aging and cognitive decline, particularly in intelligence, is a significant area of research. Understanding how and why cognitive abilities change with age can inform strategies to mitigate these effects and improve quality of life for the elderly.

Key Insights

White-Matter Hyperintensities and Cognitive Decline:
- Both periventricular and deep white-matter hyperintensities are associated with a decline in performance IQ from age 50 to 80 years, particularly in the decade from 70 to 80 years.
Sensory and Processing Speed Decline:
- Age-related declines in vision and processing speed are linked to slower cognitive processing and greater cognitive deficits. Maintaining visual sensory functioning and processing speed can mitigate declines in fluid intelligence.
Structural Brain Network Properties:
- In advanced elderly (75+), structural brain network properties are significantly correlated with general intelligence. This suggests that age-associated brain structural changes may be partially compensated by the brain's network, indicating cognitive reserve or resilience.
General Cognitive Abilities in Mice:
- Aged mice show deficits in general learning abilities, which are linked to working memory capacity and duration. Increased body weight and decreased activity are also associated with cognitive decline.
Prevalence and Stability of Cognitive Decline:
- In young-old individuals (born 1930-1932), 13.4% showed cognitive decline at baseline, increasing to 23.6% after four years. This decline was particularly noted in episodic memory, but did not predict conversion to dementia.
Early Onset of Cognitive Decline:
- Some aspects of cognitive decline begin in healthy, educated adults in their 20s and 30s. This early decline is often masked in longitudinal studies by positive retest effects.
Cognitive Decline Before Age 65:
- Cognitive abilities decline slightly before age 65, with more significant declines observed after this age. Cross-sectional studies show larger differences in cognitive performance with age compared to longitudinal studies, suggesting cohort effects.
General Cognitive Decline:
- Normal cognitive aging involves declines in processing speed, reasoning, memory, and executive functions. These declines are influenced by genetics, health, lifestyle, and neurobiological changes, though many effect sizes are small and sometimes poorly replicated.
Impact of Preclinical Alzheimer's Disease:
- Estimates of normal age-related decline in intelligence may be negatively biased by undetected preclinical Alzheimer's disease, affecting both crystallized and fluid intelligence.
Fluid Intelligence Decline:
- Fluid intelligence declines by approximately 3 to 7 IQ points per decade from ages 30 to 60. This decline is associated with deficits in organizing information, attention, and working memory.

Conclusion

Intelligence does decline with age, influenced by various factors including white-matter hyperintensities, sensory and processing speed declines, structural brain network properties, and working memory capacity. While some cognitive abilities begin to decline as early as the 20s and 30s, more significant declines are typically observed after age 65. Factors such as genetics, health, lifestyle, and preclinical Alzheimer's disease also play roles in this decline. However, maintaining sensory functions and processing speed can help mitigate some of these effects, highlighting the importance of a holistic approach to cognitive health in aging.

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Does intelligence decline with age

Summary

Consensus Meter

Introduction

Key Insights

Conclusion

Sources and full results

Relation between age-related decline in intelligence and cerebral white-matter hyperintensities in healthy octogenarians: a longitudinal study

Both periventricular and deep white-matter hyperintensities are related to decline in intelligence, but their cumulative effect explains only a small part of the differences in age-related decline in intelligence in healthy octogenarians.

Visual Function and Cognitive Speed of Processing Mediate Age-Related Decline in Memory Span and Fluid Intelligence

Older age is associated with visual decline and slower cognitive speed of processing, leading to cognitive deficits, but maintaining visual sensory functioning and processing speed may prevent a loss of fluid intelligence.

Association of Structural Global Brain Network Properties with Intelligence in Normal Aging

In advanced elderly individuals, global structural brain network properties are associated with general intelligence, suggesting that age-associated brain changes partially compensate for cognitive decline.

Age-related declines in general cognitive abilities of Balb/C mice are associated with disparities in working memory, body weight, and general activity.

Age-related declines in general cognitive abilities in Balb/C mice are linked to specific components of the working memory system, increased body weight, and decreased activity.

Prevalence and natural course of aging-associated cognitive decline in a population-based sample of young-old subjects.

Aging-associated cognitive decline is a common condition in young-old individuals, with high temporal stability and deterioration in episodic memory over a 4-year follow-up period.

When does age-related cognitive decline begin?

Age-related cognitive decline begins in healthy, educated adults in their 20s and 30s, despite prior test experience masking these declines.

Age and cognitive decline in the UK Biobank

Declines in cognitive abilities 65 are small, with slower declines in reaction time and pairs performance across all older age cohorts.

Age-associated cognitive decline.

Age-associated cognitive decline is influenced by genetics, general health, medical disorders, biological processes, diet, and lifestyle, with potential for reverse causation.

The effect of preclinical Alzheimer's disease on age-related changes in intelligence in cognitively normal older adults

Preclinical Alzheimer's disease may negatively impact age-related changes in intelligence in cognitively normal older adults, potentially biasing estimates of normal decline.

Apprehension, Memory, and Fluid Intelligence Decline in Adulthood

Adulthood decline in fluid intelligence (Gf) is associated with defects in organizing information, alertness, and concentration, with potential cohort differences.

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