Quantifying cognitive reserve in older adults by decomposing episodic memory variance: replication and extension

Area of Science:

• Neuroscience
• Cognitive Psychology
• Gerontology

Background:

• Cognitive reserve theory explains resilience to age-related brain pathology.
• Measuring cognitive reserve has been challenging.
• Previous methods proposed quantifying reserve as residual variance in memory performance.

Purpose of the Study:

• Extend reserve measurement methods to a larger, community-based sample.
• Investigate if residual reserve is explained by age.
• Examine if residual reserve predicts longitudinal language changes and dementia conversion independently of age.

Main Methods:

• Quantified cognitive reserve as residual variance in episodic memory after accounting for demographics and brain pathology (volumes of whole brain, hippocampus, white matter hyperintensities).
• Applied methods to a larger, community-based sample.
• Assessed associations with age, longitudinal language changes, and dementia conversion.

Main Results:

• The residual reserve variable was linked to higher reading ability.
• It was associated with a lower likelihood of mild cognitive impairment and dementia conversion, independent of age.
• It predicted less decline in language abilities over 3 years.
• Residual reserve moderated the negative impact of brain pathology on language decline.

Conclusions:

• The operational measure of cognitive reserve using residual memory variance is supported.
• This method facilitates research into cognitive reserve mechanisms and intervention efficacy.
• Findings highlight the protective role of cognitive reserve against age-related cognitive decline and dementia.