Materials and methods for diagnosis, prevention and/or treatment of stress disorders and conditions associated with A-beta peptide aggregation

The subject invention concerns materials and methods for detecting and diagnosing conditions associated with accumulation of Aβ peptide in neural tissue, such as Alzheimer's disease and Parkinson's disease, using the chemical cotinine. In one embodiment, the method comprises administering cotinine labeled with a detectable label to a person or animal. The presence of labeled cotinine in neural tissue is then determined. The level and/or location of cotinine can be analyzed and a diagnosis made. The subject invention also concerns cotinine labeled with a detectable label. In one embodiment, the cotinine is labeled with a radioisotope that can be detected by Positron Emission Tomography (PET) or single photon emission computed tomography (SPECT).