Plasma ADAM10 Levels and Their Association with Alzheimer's Disease Diagnosis in Older Adults with Fewer Years of Formal Education.

INTRODUCTION: Low educational attainment is a potential risk factor for Alzheimer's disease (AD) development. Alpha-secretase ADAM10 plays a central role in AD pathology, attenuating the formation of beta-amyloid peptides and, therefore, their aggregation into senile plaques. This study seeks to investigate ADAM10 as a blood-based biomarker in mild cognitive impairment (MCI) and AD in a diverse group of community-dwelling older adults, focusing on those with limited educational attainment. METHODS: Participants were recruited from public health services. Cognition was evaluated using Mini-Mental State Examination (MMSE) and Addenbrooke's Cognitive Examination - Revised (ACE-R) batteries. Blood samples were collected to analyze plasma ADAM10 levels. A logistic regression was conducted to verify the influence of plasma ADAM10 on the AD diagnosis. RESULTS: Significant differences in age, years of education, prescribed medications, and cognitive test scores were found between the MCI and AD groups. Regarding cognitive performance, both ACE-R and MMSE scores displayed significant differences between groups, with post hoc analyses highlighting these distinctions, particularly between AD and cognitively unimpaired individuals. Elevated plasma ADAM10 levels were associated with a 4.5-fold increase in the likelihood of a diagnosis of MCI and a 5.9-fold increase in the likelihood of a diagnosis of AD. These findings suggest ADAM10 levels in plasma as a valuable biomarker for assessing cognitive status in older individuals with low education attainment. CONCLUSION: This study underscores the potential utility of plasma ADAM10 levels as a blood-based biomarker for cognitive status, especially in individuals with low educational backgrounds, shedding light on their relevance in AD development and diagnosis.

ADAM10: Biomarker of mild cognitive impairment but not of cognitive frailty.

Mild cognitive impairment (MCI) associated with physical frailty gave rise to the new concept of cognitive frailty. Previous studies have suggested that MCI may represent a condition that precedes Alzheimer's disease (AD), in view of its higher conversion rate to dementia, when compared with the conversion rate of cognitively healthy older adults. Therefore, and considering that MCI represents a reversible condition, the identification of biomarkers for this condition is imperative to early diagnosis. Accordingly, this study aimed to assess whether the platelet and plasma levels of ADAM10 could be related with the concomitant conditions of MCI and physical frailty, in order to support a new blood-based biomarker for the construct of cognitive frailty. Sixty-one adults aged 60 years or older participated in this study. The results showed that ADAM10 levels are reduced in platelets (p < 0.05) and increased in plasma (p < 0.05) of older adults with MCI compared to healthy controls, regardless of the physical frailty condition. The analysis of the ROC curve of ADAM10 in platelets showed sensitivity and specificity of 72.7 and 73.9%, respectively, to correct differentiate between participants with preserved cognition from those with MCI. For plasma samples, ADAM10 presented 62.5 and 90.0%, sensitivity and specificity respectively, to differentiate the aforementioned conditions. Together with other clinical criteria blood ADAM10 could be a relevant, low-invasive, low-cost and fast processing biomarker tool to help in the early and accurate diagnosis of MCI, however this marker was not able to identify cognitive frailty.