A method for predicting the rate at which a subject will suffer from cognitive decline, comprising analysing the concentration of the T14 peptide (AEFHRWSSYMVHWK, SEQ ID NO, 3) or an aggregate thereof and comparing this with a reference value from a control, wherein a lower concentration of the peptide and/or a higher concentration of aggregated peptide, relative to the reference value, suggests that the subject will suffer from a higher rate of cognitive decline, or has a pre-disposition thereto. Also claimed is a kit comprising means to determine the concentration of the T14 peptide or an aggregate thereof.
Biomarker