While the association of plasma activity of BACE1 with cerebrospinal fluid (CSF) predictors for progression or conversion to dementia, namely tau protein and Aβ1–42 peptide [16, 17] has been previously assessed [11] the association of serum activity of BACE1 with serum levels of Aβ1 - 40 and Aβ1 - 42 has never been evaluate so far. The gene discussed is BACE1; the disease is dementia.