Opiate pharmacology and individual differences. I. Psychophysical pain measurements.

A new electric stimulation pain assessment technique using the Tursky electrode and a non-parametric analysis of subjects ratings was found sensitive to aspirin, morphine and opiate antagonists in a series of double-blind cross-over trials in normal adults. Stable individual differences in pain sensitivity (off medication) were maintained on two testing sessions 7 months apart. Older individuals were less pain sensitive than younger individuals. Men were more insensitive than women under age 30. Together, these results suggest the empiric usefulness of this pain measurement technique.