Biomarkers in Relation to Cognitive Reserve in Patients with Mild Cognitive Impairment – Proof of Concept

Background: The concept of the cognitive reserve (CR) posits that factors such as education enable compensation for the effect of brain pathology. Consequently, pathology should be more pronounced in individuals with higher CR before becoming clinically apparent. Biomarkers such as total tau (t-tau) and β-amyloid 42 (Aβ42) may be surrogates for pathology in relation to CR in patients with neurodegenerative disease. Objective: To examine the applicability of biomarkers as surrogates for pathology in relation to the CR in patients with mild cognitive impairment (MCI) either converting to dementia or remaining stable at follow-up. Method: Comparisons of baseline t-tau, Aβ42, educational years and global cognition for MCI patients either converting to dementia (n = 57) or remaining stable (n = 91) were made. Patients converting to dementia were grouped on the basis of educational level and compared considering biomarkers and neuropsychological tests. Results: Stable MCI patients were better educated, performed better cognitively, had higher Aβ42 levels and lower levels of t-tau. Converting MCI patients with higher education had lower levels of Aβ42 and performed equally in neuropsychological tests compared to those with lower education. Conclusion: Our results suggest that highly educated MCI patients subsequently converting to dementia display more amyloid pathology.