The symptoms of jumping Frenchmen of Maine usually begin after puberty or during the teenage years. Individuals affected by this disorder display an abnormal and exaggerated startle reaction consisting of jumping, screaming, flailing the arms, hitting, or throwing objects.

A startle reaction is caused by sudden or unexpected stimuli such as loud or unexpected noises, a sudden command or gesture, or unexpected physical contact such as a sudden poke in the ribs. Following the startle reaction, affected individuals may repeat back words or phrases in a parrot-like manner (echolalia) and they may involuntarily mimic or imitate movements or gestures (echopraxia). Some affected individuals may involuntarily swear or utter obscene or socially inappropriate words or phrases (coprolalia). In addition, some affected individuals may exhibit automatic or “forced” obedience after a startle response during which they automatically respond to simple commands such as jump, run or hit. Normally, these individuals would not respond to such commands.

In most cases, the symptoms lessened in frequency and severity as affected individuals grew older. The intensity of the startle response may be affected by the frequency of being startled as well as fatigue, stress or emotional tension. An affected individual must be startled in order to elicit the reaction. Jumping Frenchmen of Maine can dramatically impact daily life because of the inability to control or mediate stimuli in the course of one’s day. Individuals with jumping Frenchmen of Maine were often teased deliberately causing an increase in the frequency and severity of the episodes. Usually, the more frequently an individual is startled, the more severe and stereotyped is the response.