In an ex vivo method of differentially diagnosing dementias which include vascular dementias and/or frontotemporal lobe degenerations at least one carboxy-terminally truncated amyloidβpeptide selected from the group consisting of Aβ1 -38, Aβ1-37 and Aβ1-39 is used as a biomarker in a body fluid of a patient.
