Psychosis Resulting from Other Medical Conditions
Other disease processes that affect the brain can produce psychotic symptoms. These include strokes, some seizure disorders such as epilepsy, brain infections, or conditions that affect the body and its blood vessels and may spread to the brain in some cases.
Sometimes It Isn't Really Schizophrenia
Problems with the thyroid gland, which regulates metabolism, can cause psychoses unrelated to schizophrenia. This can take the form of hypo-or hyperthyroidism — too little or too much production of the thyroid hormone. Other medical conditions that produce psychotic symptoms are the autoimmune disease systemic lupus erythe-matosus, the viral infection AIDS, and vitamin B12 deficiency.
Brain Damage
It is possible that damage to the brain following falls, wounds, and other forms of trauma can produce psychotic symptoms in some people. They can certainly cause dramatic changes in personality. It is also possible that such injuries may be associated with the onset of schizophrenia in some vulnerable people.
Brain tumors present a less complicated situation: they, as well as some forms of epilepsy, can definitely produce psychotic symptoms. The tumors may be located in the frontal, parietal, or occipital lobes. Tumors that affect a master gland in the brain called the pituitary are also associated with the production of schizophrenia-like symptoms.
Infection
Before antibiotics became available, infection by the bacterium that causes syphilis, Treponema pallidum, was more common than it is today. In the final stage of the disease, the microbe attacks the brain. This condition, which is called neurosyphilis, was one of the most common reasons patients were admitted to psychiatric facilities in the late nineteenth and early twentieth centuries. The damage the bacterium does to the brain may cause dementia and psychosis. A blood test and examination of cerebrospinal fluid reveals the presence of the bacterium, which is readily treatable with antibiotics. The disease process can be stopped and symptoms may be relieved depending on the damage already done.
If HIV, which is the virus that causes AIDS, gets into the brain, it can produce symptoms that mimic severe mental disorders, including schizophrenia. The fact that T. pallidum and HIV can produce schizophrenia-like symptoms underlines the importance of having a complete physical exam, including specialized testing for these infections.

