Background:Currently, complementary and alternative medicine (CAM) are experiencing growing popularity, especially in former industrialized countries. However, most of the underlying physiological and molecular mechanisms as well as participating biological structures are still speculative. Specific and non-specific effects may play a role in CAM. Moreover, trust, belief, and expectation may be of importance, pointing towards common central nervous system (CNS) pathways involved in CAM.Material/Methods: Four CAM approaches (acupuncture, meditation, music therapy, and massage therapy) were examined with regard to the CNS activity pattern involved. CNS commonalities between different approaches were investigated.Results: Frontal/prefrontal and limbic brain structures play a role in CAM. Particularly, left-anterior regions of the brain and reward or motivation circuitry constituents are involved, indicating positive affect and emotion-related memory processing – accompanied by endocrinologic and autonomic functions – as crucial components of CAM effects. Thus, trust and belief in a therapist or positive therapy expectations seem to be important. However, besides common non-specific or subjective effects, specific (objective) physiological components also exist.Conclusions: Non-specific CNS commonalities are involved in various CAM therapies. Different therapeutic approaches physiologically overlap in the brain. However, molecular correspondents of the detected CNS analogies still have to be specified. In particular, fast acting autoregulatory signaling molecules presumably play a role. These may also be involved in the placebo response.

Keywords: Limbic System - drug effects, Complementary Therapies, Acupuncture, Meditation, Morphine - pharmacology, Music Therapy