The invention provides a method for detecting or monitoring Alzheimer's
disease and other forms of dementia using positron emission tomography
(PET) or single-photon emission computed tomagraphy (SPECT) and
radiolabeled, serotonin 5-HT.sub.1A receptor-specific tracers (such as
[F-18]MPPF, [F-18]FCWAY, [C-11]WAY-100635, and other radiolabeled
compounds having agonistic or antagonistic effect on serotonin
receptors), for detection or monitoring of pathological changes (i.e.,
neuronal cell loss) associated with dementia.