Blood Neurodegenerative Biomarkers and Cognitive Outcomes in Older Adults: India vs. US

Overview

This study analyzed blood-based neurodegenerative biomarkers in older adults from India (LASI-DAD) and the United States (HRS) to assess their associations with cognitive function and dementia. Elevated GFAP and NfL levels correlated with worse cognition and higher dementia risk in both populations, while the Aβ42/Aβ40 ratio showed opposite associations between countries. pTau181 was not significantly linked to cognitive outcomes in either cohort.

Background

Cognitive decline and dementia pose increasing challenges globally as populations age, necessitating early detection tools. Blood-based neurodegenerative biomarkers such as Aβ42/Aβ40 ratio, GFAP, NfL, and pTau181 offer less invasive, cost-effective alternatives to PET scans and CSF analysis for predicting cognitive impairment. These markers reflect key pathological processes in Alzheimer's disease and neurodegeneration, and their utility across diverse populations remains under investigation. Cross-national studies comparing biomarker associations with cognition can elucidate the influence of genetic, environmental, and socioeconomic factors.

Data Highlights

Key Findings

• Elevated GFAP and NfL levels are consistently associated with poorer cognitive performance and increased dementia risk in both Indian and US older adults.
• GFAP and NfL predict cognitive decline over time in the US cohort but not in the Indian cohort.
• The Aβ42/Aβ40 ratio shows divergent associations: higher ratios correlate with worse cognition in the US but better cognition in India.
• Phosphorylated Tau at Threonine 181 (pTau181) does not show significant associations with cognitive outcomes in either population.
• These biomarkers may also serve as indicators of general aging, as suggested by their relationship with mortality.

Clinical Implications

Blood-based biomarkers GFAP and NfL can be useful tools for identifying older adults at risk of cognitive impairment and dementia across diverse populations. However, the differing associations of the Aβ42/Aβ40 ratio between India and the US highlight the need for population-specific interpretation of biomarker results. Incorporating these biomarkers into clinical and epidemiological settings may improve early detection and monitoring of neurodegenerative processes, but clinicians should consider environmental and demographic context.

Conclusion

Blood neurodegenerative biomarkers demonstrate significant associations with cognitive function and dementia risk in older adults from both India and the US, though some markers exhibit population-specific patterns. These findings support the potential of blood-based assays as accessible tools for dementia risk assessment globally, while underscoring the importance of cross-national research to tailor biomarker interpretation.

References

1. LASI-DAD & HRS Study -- Linking Blood Neurodegenerative Biomarkers to Cognitive Abilities and Dementia in Older Adults