1. A system for diagnosing, monitoring, or prognosing Alzheimer's disease, the system comprising: (a) an apparatus comprising at least one sensor comprising nanomaterials selected from single walled carbon nanotubes coated with cyclodextrin or a derivative thereof and metal nanoparticles capped with an organic coating; (b) a detection means; and (c) a processing unit comprising a learning and pattern recognition analyzer wherein the learning and pattern recognition analyzer receives sensor output signals and compares them to stored data.