MAPT and Mental deterioration: CSF concentrations of brevican and neurocan positively correlated with age and markers of neurodegeneration (total tau, phosphorylated Tau, neurofilament‐L, and Aβ1‐40) and cognitive decline in AD patients [281, 282], although the lack of significant difference in CSF concentrations between AD patients and cognitively normal controls [283, 284, 285] questions their suitability as AD‐specific biomarkers.