beta-Endorphin immunoreactivity and acute behavioral distress in children with leukemia

Endogenous opiates have been implicated in pain and stress experiences. In order to directly assess the relationship between endorphin activity and acute behavioral distress, beta-endorphin immunoreactivity (beta-EPI) was measured by radioimmunoassay in cerebrospinal fluid of 75 children with acute leukemia undergoing routine lumbar puncture. These data were related to four measures of behavioral distress collected during the procedure. For children 4 years of age and above, beta-EPI correlated inversely with age (r = -.31,p less than or equal to .05). All behavioral measures also inversely correlated with age (r = -.26 to -.67,p less than or equal to .05 to .001). Females had a significantly lower mean beta-EPI than males (p less than or equal to .01), and exhibited greater behavioral distress. beta-EPI and behavioral measures interacted with the use of specific antileukemia agents. L-Asparaginase was associated with lower beta-EPI (p less than or equal to .05), while prednisone was associated with lower behavioral distress on three of the four measures (p less than or equal to .05 to .01). After controlling for age, sex, and chemotherapy, beta-EPI and nurse ratings of anxiety were positively correlated (partial correlation coefficient = .31, p less than or equal to .05). Correlations between beta-EPI and other behavioral measures demonstrated positive trends. Results of this study are interpreted as support for the reactive nature of beta-EPI in cerebrospinal fluid to acute distress, and may help explain documented sex differences in distress behavior. Potential clinical implications and directions for further research are discussed.