Electrodermal activity as a possible physiological marker for acupuncture.

Change in amplitude of skin potential is one of the physiological indicators of electrodermal activity (EDA) and has been associated with the onset of a variety of sensory, cognitive and emotional stimuli. This study investigated the EDA physiological response to manual acupuncture. A group of 60 healthy female volunteers were recruited into the study of which 30 were randomly assigned to a control group (no acupuncture) and 30 to the experimental group (received acupuncture). The experimental group attended three sessions in which acupuncture intervention consisting of unilateral manual stimulation of acupuncture points LU7 and KD6. Results showed that the insertion, stimulation and withdrawal of the acupuncture needles were associated with significant changes in EDA. The insertion of the needle was associated with the highest change in skin potential while the three consecutive manipulations of the needles showed a decline in EDA amplitude, thought to be consistent with physiological habituation. Anxiety level and previous familiarity with acupuncture did not influence outcomes. It is postulated that the change in EDA during needle insertion is non-specific to the type and the function of acupuncture points; however, EDA response may be associated with the precise location of the acupuncture point. If further studies confirm such findings, then EDA may become a valuable physiological marker for the acupuncture phenomenon.