High levels of testosterone may be connected with higher risk for hallucinations, aggression and other acting-out actions in men that already have Alzheimer's disease. Lower testosterone levels increase the risk of developing Alzheimer's disease, according to studies. However, once the onset of Alzheimer's is established, higher levels of the hormone in the system can aggregate it. Dr. James Hall, a Professor of Psychiatry and Behavioral Health at the University of North Texas Health Science Center, said in a press release: "But once someone already has Alzheimer's, higher levels of testosterone are related to acting-out behaviors. Those behaviors, such as agitation and delusions, occur at some point in at least 70 percent of Alzheimer's patients." These results raise some concerns regarding the frequent practice of prescribing testosterone-replacement therapies to older men. "What we're showing is that testosterone can have a negative impact on patients with Alzheimer's disease. It may be crucial to consider the possible unintended consequences before a patient is placed on testosterone-replacement therapy,"