Longitudinal stability in working memory and frontal activity in relation to general brain maintenance

Area of Science:

• Neuroscience
• Cognitive Aging Research
• Neuroimaging

Background:

• Cognitive functions, particularly working memory (WM), show varied trajectories in aging.
• The neural mechanisms underlying preserved or declining WM in older adults are not fully understood.

Purpose of the Study:

• To investigate the longitudinal brain mechanisms associated with stable versus declining working memory (WM) in healthy older individuals.
• To examine the relationship between WM trajectories and prefrontal cortex (PFC) function, as well as general brain maintenance markers.

Main Methods:

• A 5-year longitudinal study using in-scanner and offline 3-back task data.
• Analysis of functional magnetic resonance imaging (fMRI) data focusing on the PFC.
• Assessment of neuroimaging markers for neurotransmission, vascular health, and neuronal integrity (ventricles, hippocampus).

Main Results:

• Individuals with stable WM showed maintained PFC functional responses over time.
• Those with declining WM exhibited reduced longitudinal PFC activity.
• The stable WM group had higher levels of brain maintenance markers (neurotransmission, vascular health).
• WM decline rate correlated with increased ventricle size and hippocampal changes, indicating reduced neuronal integrity.

Conclusions:

• Prefrontal cortex (PFC) function plays a crucial role in maintaining working memory (WM) in aging.
• General brain maintenance, encompassing vascular and neurotransmitter systems, contributes to cognitive stability in older age.
• Heterogeneity in longitudinal WM trajectories is explained by both PFC function and overall brain health.