LPA and Alzheimer disease: Some studies have demonstrated a significant positive correlation between serum concentrations of Lp(a) and increased risk of AD (Solfrizzi et al., 2002), while some studies have indicated a negative correlation (Gong et al., 2022), and others have found no significant difference in Lp(a) concentrations between AD patients and healthy controls (Ray et al., 2013; Ban et al., 2009).