Electrodermal, cardiac, and respiratory activity to repeated cold pressor stimulation in drug addicts

Skin conductance responses (SCRs), heart rate (HR), and respiration were recorded in various rest, cold pressor (CP), and CP recovery phases in 20 former drug users (DG) and 20 control Ss (CG), matched on sex and age in a repeated measures design. With regard to the abused drugs (barbiturates and narcotic analgesics), the hypothesis was tested that autonomic responses are decreased after long-term use of barbiturates and narcotic analgesics. The results partially supported that hypothesis: (a) SCRs, HR change, and HR deceleration were significantly lower in DG compared to control Ss; (b) HR baseline, respiration rate, and amplitude, however, tended to be increased in DG in the rest and CP phases. A second hypothesis, addressed to different habituation rates of SCRs and HR in both groups, was confirmed for SCRs and partly for HR, indicating that the habituation rates of SCRs, HR change, and HR deceleration were greater in DG than in CG. A third question concerned the consistency of SCR and HR results in both sessions. A trend for consistent results was found as the direction of the group differences was the same in sessions 1 and 2. The CP results were compared with similar findings in the same Ss during visual and auditory stimulation.