Habituation and sensitization processes in depressive disorders

The aim of the present study was to investigate further into habituation an d sensitization processes in depressive disorders. The depressive subjects were 27 outpatients. All of them were diagnosed according to DSM-III-R crit eria. Controls were 27 normal subjects. The amplitudes of electrodermal res ponses and the basal levels were recorded during a stimuli series of 15 80- dB tones and of 1 100-dB tone in the 11th trial. The depressive patients di splayed lower basal conductance levels and lower conductance amplitudes in orienting responses to the fi rst stimulus and to stimulus change. No diffe rences were found in conductance response amplitudes of stimuli series, alt hough a tendency towards smaller conductance amplitudes in depressive patie nts was observed before stimulus change. A trend towards habituation was de tected in both groups, but no differences between them were present, neithe r the habituation velocity of depressives was found to be unlike normals. O ur results display lower responsivity in depressive patients, which reflect s alterations in the sensitization process.