Proportion of cognitive loss attributable to terminal decline

Area of Science:

• Neuroscience
• Gerontology
• Cognitive Psychology

Background:

• Cognitive decline is a significant concern in aging populations.
• Understanding the drivers of late-life cognitive loss is crucial for interventions.
• Distinguishing between normal aging and terminal decline is important for accurate assessment.

Purpose of the Study:

• To quantify the proportion of cognitive decline in older adults that occurs during the terminal period before death.
• To analyze the acceleration of cognitive decline preceding death.
• To estimate the incidence of dementia and mild cognitive impairment (MCI) in the preterminal and terminal phases.

Main Methods:

• Longitudinal cohort study of 1,071 older adults without dementia at enrollment.
• Annual cognitive assessments over an average of 10.6 years.
• Change point models to estimate the onset and rate of terminal acceleration in cognitive decline.

Main Results:

• Global cognitive decline accelerated significantly around 3.7 years before death, a 7-fold increase.
• Terminal decline accounted for 71% of overall global cognitive loss.
• Specific cognitive domains like memory and processing speed showed substantial contributions from terminal decline, ranging from 52% to 70%.

Conclusions:

• The majority of cognitive loss observed in late life is driven by the terminal decline phase.
• Dementia incidence was significantly higher in the terminal period compared to the preterminal period.
• These findings highlight the substantial impact of the period preceding death on cognitive function in older adults.