Infections of the central nervous system

Central nervous system (CNS) infections, caused by various pathogens, can lead to a wide range of neuropsychiatric sequelae, including acute psychosis, mood disorders, and chronic dementias. Early recognition is critical as brain infections are often treatable and possible neuropsychiatric illness can be reversed if the diagnosis is timely. In addition to psychiatric symptoms, CNS infections may also present with other signs such as fever, meningism, cranial nerve deficit, and seizures. Although the presence of these additional features can often provide a clue to an underlying CNS infection, they are not always present; hence CNS infections should be considered in the differential diagnosis of psychiatric patients in certain situations. In this chapter, CNS infections that have psychiatric manifestations or have psychiatric sequelae are discussed, in particular HIV, neurosyphilis, meningitis, and encephalitis.