The present invention is directed to methods of diagnosing Alzheimer's disease in a subject by detecting alterations in the ratio of specific phosphorylated MAP kinase proteins in cells after stimulation with a protein kinase C activator. The Alzheimer's disease-specific molecular biomarkers disclosed herein are useful for the diagnosis of Alzheimer's disease, monitoring the progression of Alzheimer's disease in a subject and in screening methods for the identification of compounds for treating or preventing Alzheimer's disease. The invention is also directed to kits containing reagents for the detection and diagnosis of Alzheimer's disease using the Alzheimer's disease-specific molecular biomarkers disclosed herein.