The influence of different pain states on pain perception and cognitive functions

Sammanfattning: The general aim of this thesis was to investigate the effect of different pain stateson pain perception and cognition.In the first study, the effect of different pain qualities (duration, persistence, andintensity) on deep pressure pain thresholds in a pain-free body part among patientswith acute pain, long-lasting regularly recurrent pain, and long-lasting persistentpain, and pain-free controls was investigated. Such general deep pressure painthresholds were only significantly lower in the group with long-lasting persistentpain when compared to the healthy controls, suggesting that deep tissuehypersensitivity primarily occurs in patients with long-lasting, persistent pain.In the second study, the relationship between the same pain qualities and cognitiveperformance in the form of sustained attention, cognitive control, and psychomotorability was investigated. Overall, patients with long-lasting, persistent pain showedcognitive impairment on a wider range of cognitive tasks compared to patients withacute or long-lasting, regularly recurrent pain, using pain free controls asbenchmark. The results further suggest that persistence and duration, rather thanpain intensity, contribute to impaired cognitive function in clinical musculoskeletalpain states.In the third study, the effect of acute, experimental pain on abstraction wasexamined in a laboratory experiment where pain was induced with a cold pressorapparatus. The results were consistent with the null hypothesis, suggesting thatabstraction is immune to acute, experimental pain.In the fourth study, the correlation between clinical pain, abstraction and selfcontrolwas examined in patients suffering from musculoskeletal pain of differentduration, persistence and intensity. The results suggest that abstract thinking isreduced with increasing pain intensity and pain persistence. This was also the casefor self-control, although depression seems to mediate this relationship.In conclusion, compared to other pain states, patients who experience long-term,persistent pain, seem to suffer from a broader range of impaired cognitive abilities.Further, deep tissue hypersensitivity seems to develop in patients with long-termpersistent pain, but not in other pain states, which may contribute to the impairedcognitive performance observed in this patient group. The results have importantpractical implications for patients in the clinic and their everyday lives.