Cohort effects in age-associated cognitive trajectories

Area of Science:

• Epidemiology
• Neuroscience
• Gerontology

Background:

• Cognitive impairment and dementia prevalence in the US remained stable or declined from the 1980s-1990s.
• Higher educational attainment in recent cohorts is a proposed, yet unverified, reason for improved cognitive function over time.

Purpose of the Study:

• To investigate cohort effects on age-associated cognitive function trajectories.
• To determine if educational attainment explains observed cohort effects in cognitive function.

Main Methods:

• Utilized data from two large, prospective, population-based dementia studies (1987-2012).
• Compared neuropsychological test trajectories across four birth cohorts (1902-1943) in psychomotor speed, executive function, and language.
• Employed mixed-effects models to examine Age × Cohort interactions, with and without controlling for education.

Main Results:

• Significant cohort effects were observed in all three cognitive domains, with notable differences between the earliest and most recent cohorts.
• Executive functions exhibited the most pronounced and persistent differences between the recent and older cohorts.
• Educational attainment did not significantly reduce the observed cohort effect associations.

Conclusions:

• Cohort effects significantly impact all examined cognitive domains, persisting even after accounting for educational attainment.
• Factors beyond education are likely the primary drivers of observed cohort effects in cognitive decline patterns.