DaSilva AF, Nascimento TD, DosSantos MF, Lucas S, van HolsbeecK H, DeBoer M, Maslowski E, Love T, Martikainen IK, Koeppe RA, Smith YR, Zubieta JK. Ann Clin Transl Neurol. 2014 Jun 1;1(6):439-444.
Data Visualization for Individual and Group Average Pain Area and Intensity in migraine patients during the attack. Figure 1 (page 440). In addition, No correlations were found with the averages of attack intensity, extension, or frequency separately. However, when intensity and extension of the current headache attacks were accounted for together (P.A.I.N.S. from GeoPain) there was a moderate negative correlation with endogenous opioid brain activation (r = 0.61).