Aging gracefully: compensatory brain activity in high-performing older adults

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Aging Research

Background:

• Cognitive aging varies significantly among older adults.
• The Hemispheric Asymmetry Reduction in Old Adults (HAROLD) model describes reduced prefrontal cortex (PFC) asymmetry in older adults.
• Two hypotheses, compensation and dedifferentiation, explain HAROLD's implications for cognitive function.

Purpose of the Study:

• To investigate the neural basis of differential cognitive aging patterns.
• To compare the compensation versus dedifferentiation hypotheses of cognitive aging.
• To examine prefrontal cortex (PFC) activity differences between young, low-performing older, and high-performing older adults.

Main Methods:

• Positron Emission Tomography (PET) and functional Magnetic Resonance Imaging (fMRI) were employed.
• Prefrontal cortex (PFC) activity was measured during memory tasks (recall and source memory).
• Participants included young adults, low-performing older adults, and high-performing older adults.

Main Results:

• Young adults showed right PFC activation for source memory compared to recall.
• Low-performing older adults recruited similar PFC regions as young adults.
• High-performing older adults exhibited bilateral PFC engagement, indicating reduced asymmetry.

Conclusions:

• Reduced PFC asymmetry (Hemispheric Asymmetry Reduction in Old Adults or HAROLD) is linked to successful cognitive aging (compensation hypothesis).
• Low-performing older adults may use neural networks inefficiently rather than showing dedifferentiation.
• High-performing older adults demonstrate neuroplasticity and cognitive reserve through network reorganization.