Annäherung und Vermeidung bei chronischem Schmerzsyndrom der Skelettmuskulatur: Die Rolle des Transfers von Pavlovschem zu instrumentellem Verhalten
Zusammenfassung der Projektergebnisse
In our everyday life, we seek to approach positive, rewarding stimuli and situations and to avoid negative, aversive ones. In individuals who suffer from chronic pain, it is assumed that these approach-avoidance tendencies are shifted or disrupted, resulting in a negative cycle of maintaining dysfunctional pain-related behavior. For example, chronic pain patients might benefit less from positive events to reduce pain, but rather focus on pain relief and related processes. The project aimed to determine the role of approach and avoidance behaviour, and reward learning processes in chronic back pain and examined behavioral, peripheral and central correlates. Moreover, affective symptoms, in particular depression and anxiety, as well as environmental factors and experiences such as the experience of early aversive life events were further assessed. These may critically affect learning and related behaviour, which could trigger the persistence of pain symptomatology. We found that patients need stimuli at very high valence levels to transfer learned reward associations into respective (approach) behavior, while healthy individuals did show a respective transfer to any valent stimulus. This was associated with changes in prefrontal-striatal-limbic circuitry, and with pain symptoms duration. Moreover, anxiety and depression strongly modulated these associations, and childhood trauma was shown to further play an important role in pain avoidance and the transfer of learned reward associations into behavior. Factors related to approach-avoidance behavior differentiated between chronic back pain patients from healthy controls, and may thus represent significant predictors for the presence of chronic pain, including the determination of pain and sensory symptoms in the patients. These data provide further insights into mechanisms relevant for chronic pain development and maintenance. The data can be discussed in the context of transition processes from acute to chronic pain and related coping / compensatory behavior, also in the course of chronic pain, and can inform clinical interventions to guide pharmacological and psychological strategies for chronic pain patients, also with respect to comorbid high levels of depressive mood and anxiety. How this is transferred to pain relief, which is normally treated as reward, needs to be investigated in future studies in more detail: responsivity to different frequencies of a painful (electrical) stimulus might change in chronic back pain patients over time, and compared to healthy individuals, thus requiring a specific, possibly more individualized, experimental procedure as compared to procedures that use pain-unrelated rewards.
