A study published in the November issue of the Journal of Alzheimer's Disease provides an insight into normal, physiological levels and association between proteins involved in development of Alzheimer's disease. A group of scientists and physicians from the University of Washington and Puget Sound Veterans' Affairs Health Care System in Seattle, in collaboration with groups from the University of Pennsylvania and the University of California San Diego, performed a study in cognitively normal and generally healthy adults, from young to old (age range 21-88 years), of both genders, measuring levels of different brain-derived molecules associated with Alzheimer's disease.