Hallmarks of healthy cognitive aging: Inter-individual differences in aging trajectories

Area of Science:

• Neuroscience
• Gerontology
• Cognitive Science

Background:

• Cognitive aging is highly variable, with chronological age being a poor predictor of cognitive health.
• Individual differences in cognitive aging stem from diverse biological trajectories at molecular, cellular, and network levels.

Purpose of the Study:

• To synthesize biological hallmarks of healthy cognitive aging.
• To examine the role of the medial temporal lobe in cognitive variability.
• To identify mechanisms shaping individual cognitive aging trajectories.

Main Methods:

• Review of studies on longitudinal cognitive trajectories in humans.
• Focus on distinguishing individuals with retained learning capacity from those with decline.
• Analysis of mechanisms including network organization, synaptic plasticity, and neurogenesis.

Main Results:

• Cognitive decline is linked more to network regulation and synaptic plasticity alterations than neuronal loss.
• Key mechanisms include network organization, excitation-inhibition balance, neuromodulation, glial/vascular health, neurogenesis, and homeostasis.
• Disruptions in core regulatory mechanisms can propagate across organizational levels.

Conclusions:

• Cognitive resilience depends on preserving coordinated network dynamics.
• A system-level framework explains cognitive aging.
• Longitudinal, multidimensional approaches are needed to identify early shifts and inform interventions for lifelong cognitive health.