Not just the medial temporal lobe: Precuneus and posterior cingulate volumes relate to plasma biomarkers and cognition in a sub-Saharan African cohort.

INTRODUCTION

The precuneus and posterior cingulate-key regions in early Alzheimer's disease (AD)-undergo atrophy before clinical symptoms emerge. Limited research in sub-Saharan Africa (SSA) has explored how blood-based biomarkers relate to brain changes and cognition. This study examined these associations in older adults with dementia in Kinshasa, Democratic Republic of Congo (DRC).

METHODS

A total of 117 adults (≥ 65 years; five dementia, and 58 controls) completed neuropsychological testing and blood draws, with 75 completing neuroimaging. Plasma amyloid-beta (Aβ) 40, Aβ42, pTau181, pTau217, and neurofilament light chain (NfL) were analyzed using single molecule array (Simoa). Regional volumes were obtained via Freesurfer. Linear models assessed biomarker, volume, and cognitive associations.

RESULTS

Lower Aβ42/40 and higher NfL levels were associated with reduced posterior cingulate and right precuneus volumes. Posterior cingulate atrophy correlated with poorer semantic fluency, memory, and executive function. Male sex and higher education were linked to larger volumes.

CONCLUSIONS

Plasma Aβ42/40 and NfL are promising biomarkers of AD-related brain atrophy in SSA. Results support region-specific screening approaches in global dementia research.

HIGHLIGHTS: First biomarker-neuroimaging study of dementia in sub-Saharan Africa (SSA). Lower amyloid-beta (Aβ) 42/40 linked to reduced posterior cingulate volumes. Higher plasma NfL associated with right precuneus and PCC atrophy. Posterior cingulate atrophy predicted memory and executive dysfunction. Study supports plasma biomarkers for AD screening in SSA settings.