data that excluded individuals who developed dementia less than 3 years or more than 20 years from baseline showed an adjusted hazard ratio of 5.77. In addition, the rates of dementia were higher among individuals hospitalized for urinary tract infections, respiratory infections, hospital- acquired infections, skin infections, and blood and circulatory system infections (Bohn et al., 2023), all of which are common infections in older adults.

pathogens, and a comprehensive discussion of all such pathogens is not included here. In general, however, encephalitis is typically described as primary or sec­ondary. Primary encephalitis refers to an infection directly to the brain. Secondary encephalitis is a post- infection encephalitis in an immune response to a dormant virus or immunization (i.e., attenuated virus). While several viruses have been im­plicated in encephalitis, the most common viral infections resulting in encephalitis include herpes simplex, Epstein– Barr, varicella zoster, enteroviruses, and arbo­viruses. As with meningitis, encephalitis results in multiple psychiatric and neu­rological sequelae. Inammation results in edema, leading to tissue damage and ischemic injury. ere is also an increased risk of stroke and seizure, and multiple studies demonstrate an increased risk of dementia, even aer infection recovery (Campos et al., 2021; Hokkanen & Launes, 1997). Individuals with measles can have post- infectious encephalitis. is occurs when there is a delay in encephalitis, sometimes days or weeks aer the initial infection, making it dicult to associate the encephalitis with illness. Transverse myelitis occurs when infection results in inammation of the spinal cord. is is frequently related to enteroviruses but can occur in multiple viral infections. Common symptoms of transverse myelitis in­clude pain, sensory changes, weakness, and bladder or bowel control diculties when lower aspects of the spine are involved. HIV- associated cognitive change is frequently identied in the literature, and numerous studies have demonstrated that HIV can result in dementia and increase the risk of other conditions, such as Alzheimer’s disease. e John Cunningham virus (commonly called the JC virus) can result in demyelination throughout the CNS, resulting in progressive multi­focal leukoencephalopathy. e JC virus is endemic in most populations, with 70– 90 percent of the population having this virus in a harmless dormant form. However, the risk of progressive multifocal leukoencephalopathy from the JC virus increases among individuals who are immunocompromised. For instance, this con­dition has been identied among individuals with AIDS and multiple sclerosis or other immunocompromised states. Common symptoms include dementia, blind­ness, paralysis, and seizures. Progressive multifocal leukoencephalopathy is typi­cally fatal (Blumenfeld, 2010).