A family-based investigation of cold pain tolerance

In the present study the question was addressed whether sensitivity to experimental pain stimuli differs between families, which are previously characterized by the degree of cold tolerance (very insensitive or very sensitive) of one family member. A total of 232 healthy medical students were screened for cold pain tolerance employing a cold pressor test. Subsequently 50 of them were investigated in detail under laboratory conditions. The water temperature was 1 degrees C, the maximum time in water 3 min, cold pain was rated on a 101 step numerical rating scale every 10s. Two of the most cold pain sensitive (shortest time in ice water) and insensitive (lowest ratings) students were selected and as many as possible of their family members were recruited. In all of them cold pressor test, pinprick pain threshold, pressure pain threshold, skin temperature, hospital anxiety and depression scale and COMT val158met polymorphism (with the exception of three individuals) were assessed. Analysis (ANOVA) revealed that the cold pressor results of the students predicted the mean ratings (p<0.04) and the time in ice water (p<0.03) of their own families. Furthermore, pinprick pain threshold (p<0.002) and to a lesser extent pressure pain thresholds (p<0.03) were significantly related to cold pain tolerance. The other variables, including the COMT polymorphism, were not related to cold pain tolerance in our study. In conclusion our results suggest that cold pain tolerance may be at least partially inherited. Genetic or environmental factors might explain family clustering of cold pain sensitivity.