This is an 18 week (2 weeks run-in, 16 weeks double blind) trial, to determine if an antiviral drug, valacyclovir (Valtrex) is helpful in treating the symptoms of psychosis, a form of a mental disorder.

There is evidence that some of the symptoms of psychosis may be related to past infection with common viruses.

Researchers are looking to recruit a total of 100 subjects with evidence in the past, of exposure to at least 1 of 3 viruses. The viruses include herpes type 1 (HSV-1, which causes cold sores of the lip and has affected about 6/10 people in Vancouver), herpes type 2 (HSV-2 which causes genital sores, and has affected less than 1/10 people in Vancouver) and cytomegalovirus (CMV, which causes few symptoms but has affected 8/10 people in Vancouver). People who have been infected with these viruses in the past develop antibodies in the blood. The antibodies can be measured in blood, and are a test of whether or not there was infection in the past, and possibly affecting the symptoms of psychosis.

Inclusion Criteria:

• Subjects antipsychotic, mood stabilizing and antidepressant drug treatment must have been stable for at least 3 months, and there is no plan to change the drug treatment during the 4-month phase of the study.
• Subjects must be seropositive for HSV-1, HSV-2 and/or CMV.
• Subjects must achieve a level of understanding and expressive capacity sufficient to communicate adequately with the study coordinator and to participate in cognitive testing.
• Subjects must be able to provide written informed consent.

Exclusion Criteria:

• Females of childbearing age will agree not to become pregnant and will agree to use a medically acceptable method of birth control.
• Inability to participate in cognitive testing due to severe persistent psychosis or other condition.
• Mental handicap.
• Subjects with known hypersensitivity or allergy to valacyclovir or acyclovir.
• Patient taking nontopical antiviral medications with anti-herpes activity on a regular basis