While evidence indicates depression as a risk factor for Alzheimer’s disease (AD) that may accelerate development and progression, the effects of other psychiatric disease on AD as less well known. For a study, researchers screened 1,500 patients with AD for history of depression, anxiety, bipolar disorder, schizophrenia, and post-traumatic stress disorder, determining disease prevalence and age at onset, demographics, and other AD risk factors. Participants with depression or anxiety were 2.1 and 3.0 years younger at AD age of onset when compared with other participants. Age at onset reductions doubled with each additional psychiatric diagnosis patients had, such that one disorder reduced age at onset by 1.5 years, two reduced it by 3.3 years, and three or more reduced it by 7.3 years. Participants with depression and anxiety were more likely to be female and had fewer typical AD risk factors. Participants with depression had significantly higher rates of autoimmune disease, whereas those with anxiety had a greater frequency of seizures, when compared with other participants.
