Traumatic brain injury and psychiatric disorders in dementia due to Alzheimer's disease Lead Investigator: Erin Abner Institution : University of Kentucky E-Mail : erin.abner@uky.edu Proposal ID : 649 Proposal Description: This study has two aims: (1) We will evaluate the association between Traumatic Brain Injuries (TBI) and psychiatric conditions in patients who present with medically diagnosed dementia due to Alzheimer???s disease. (2) We will evaluate the association between TBI and brain pathology among such participants who have come to autopsy. Methods: A cross-sectional analysis will examine initial visit data obtained from the National Alzheimer???s Coordinating Center (NACC) Uniform Data Set and Neuropathology databases (December 2014 freeze) to assess whether there is an association between people who have dementia due to AD, psychiatric symptoms(measured by Neuropsychiatric Inventory) as well as diagnosed psychiatric illnesses (measured by reported Health History), and reported TBIs. In addition, we will perform a longitudinal analysis to assess whether TBI predicts incident or worsening psychiatric symptoms and illness. Finally, we will assess the association between TBI, psychiatric symptoms and illness, and three neuropathological outcomes: neuritic plaques, neurofibrillary tangles, and Lewy bodies.