Cortical Amyloid Burden Relates to Basal Forebrain Volume in Subjective Cognitive Decline

Area of Science:

• Neuroimaging
• Neuropathology
• Cognitive Decline

Background:

• Cholinergic basal forebrain (BF) atrophy is common in Alzheimer's Disease (AD) but less understood in earlier stages.
• Subjective cognitive decline (SCD) represents an early stage in the AD continuum.

Purpose of the Study:

• To investigate basal forebrain (BF) volume reductions in individuals with subjective cognitive decline (SCD) who exhibit Alzheimer's Disease (AD) pathological changes.
• To explore the relationship between BF volume and amyloid burden in SCD.

Main Methods:

• Compared MRI-based BF volumes in amyloid-positive versus amyloid-negative SCD individuals (N=24 each).
• Utilized Florbetaben PET for amyloid status and Centiloid (CL) for cortical amyloid burden.
• Assessed associations between BF volume and CL values.

Main Results:

• BF total volume and Ch4 subregion volume approached significance for reduction in amyloid-positive SCD individuals (p=0.061 and p=0.059, respectively).
• Significant inverse correlations were found between BF volumes (total and Ch4) and cortical amyloid burden (CL values).

Conclusions:

• Amyloid-positive SCD individuals show early alterations in basal forebrain (BF) integrity, supporting their transitional role in the AD continuum.
• The findings suggest an incremental process where increasing amyloid burden impacts BF integrity.
• Further research is needed to determine if BF changes occur at lower amyloid levels detectable by PET.