A prodrome is a early sign or symptom indicating the onset of a disease or psychological condition. It is a general term, but is often applied to specific medical conditions where it appears, such as schizophrenia and infectious disorders like the measles and chicken pox. In the case of infectious diseases, the disease is often considered most contagious during the prodromal stage.
In conditions involving the psychology of an individual, the prodromal stage is characterized by a diminished ability to interact in a normal manner in the usual social or occupational environment. This prodrome period is known to precede actual psychosis, or the development of a mental disorder, by a period of less than a year. Sometimes a prodrome period can be a prolonged and gradual deterioration towards psychosis, however, that takes place over the course of several years.
Research into prodromal periods of deterioration has shown that neurocognitive dysfunction can be measured with functional magnetic resonance imaging (MRI) before the patient has any awareness of a deteriorating condition. When a psychotic break occurs and an individual is consciously aware of a psychosis condition for the first time, the condition has likely already progressed considerably. Ongoing research into prodrome indicators of schizophrenia are focused on three well-known symptoms that occur in schizophrenia cases: auditory comprehension, attention spans, and working memory states.
In infectious diseases such as herpes and chicken pox, the prodrome stage is usually short, and indicators are a skin rash or itchiness and a rise in temperature respectively, that occur a few days before the diseases manifest. This is true in the case of herpes even though the virus can lay dormant in the body for years. When a virus enters a prodrome stage, it has begun to multiply and symptoms soon follow. When viruses are present in the body but dormant, they are not considered infectious to other individuals until they enter a prodrome stage, which is followed in two to five days by the fully active illness stage.
Prodrome symptoms can be vague and easily attributable to a multitude of health concerns. One prominent example of this is the occurrence of a migraine, which is a condition of moderate to severe headaches. Conditions that can be present in the prodrome stage, but only tend to show up in 40 to 60% of individuals, can include a wide variety of changes in mood from depression to euphoria. Other conditions can be sleepiness, strange food cravings, stiff muscles, among others.