The invention relates to methods of diagnosing Alzheimer's disease (AD) in a subject and methods of determining the prognosis in patients with AD. The adhesion molecules P-selectin and L-selectin are described for the first time for use as biomarkers to aid in the diagnosis of AD. The invention further describes the use of one or more of L-selectin, MCP-1, IL-1α, IL-8 and IFN-γ to aid in the prognosis of either accelerated cognitive decline (ACD) or slow cognitive decline (SCD) in patients with AD.