Relationship between brain AD biomarkers and episodic memory performance in healthy aging

Area of Science:

• Neuroscience
• Gerontology
• Medical Imaging

Background:

• Brain biomarkers for Alzheimer's disease (AD) can be detected decades before clinical symptoms manifest.
• Understanding early cognitive changes and their association with brain structure is crucial for identifying individuals at risk.
• Previous research often focuses on symptomatic populations, leaving a gap in knowledge regarding healthy, late middle-aged individuals.

Purpose of the Study:

• To investigate the association between brain biomarkers and episodic memory performance in healthy adults aged 50-70.
• To determine if these associations differ between younger (50-59 years) and older (60-70 years) healthy individuals.
• To explore the role of hippocampal volume, amyloid-beta (Aβ) levels, and tau/neuroinflammation burden in memory function.

Main Methods:

• Sixty healthy participants (50-70 years) with negative amyloid-beta (Aβ) biomarker status were recruited.
• Cognitive performance was assessed using the Free and Cued Selective Reminding Test (FCSRT), Logical Memory test, and Mnemonic Similarity Task (MST).
• Brain imaging techniques, including PET for Aβ and tau/neuroinflammation, and MRI for hippocampal atrophy, were utilized.

Main Results:

• Positive associations were found between Mnemonic Similarity Task (MST) scores (recognition and pattern separation) and hippocampal volume in participants over 60 years old.
• No significant associations were observed between memory performance and Aβ or tau/neuroinflammation burden in either the younger or older age groups.
• Hippocampal volume emerged as a key correlate of specific memory functions in older healthy adults.

Conclusions:

• Hippocampal volume, rather than amyloid or tau pathology, is associated with certain memory functions in healthy older adults.
• Visual recognition memory and the ability to discriminate lures, as measured by the MST, may serve as early cognitive indicators of memory decline.
• These findings highlight the potential of specific cognitive tasks and structural brain changes as early markers in aging populations.