Gender but not stimulus parameters influence prolactin response to electroconvulsive therapy

Abstract

The post-ictal prolactin (PRL) response represents one of the most consistent findings of electroconvulsive therapy (ECT), but correlates variably with the gender of the patient, ECT stimulus waveform, dose and electrode placement. Forty patients with endogenous depression (29 drug-naive) received either high-energy (240 mC) or low-energy (60 mC) bilateral brief-pulse ECT once or three times a week. The PRL and growth hormone (GH) levels were estimated using double antibody radioimmunoassay. The average post-ECT PRL levels differed significantly from the pre-ECT levels, with a seven- to nine-fold increase in PRL at each week of treatment. No such difference was observed in the GH levels. All patients showed an increase in PRL levels, whereas 42% failed to show an increase in GH levels. The delta PRL response (difference between post-ECT and pre-ECT serum hormone levels) was not significantly different between the drug-naive and medicated patients nor between the high-energy and low-energy groups at first ECT. Similarly, no difference was observed between the once-weekly and thrice-weekly groups at the third week of ECT. At each week of treatment, the delta PRL was significantly higher in females than in males, unlike the GH response. Electroencephalographic (EEG) seizure duration did not correlate with either delta PRL or delta GH at first ECT and third week ECT. Apart from gender, none of the variables, such as age, baseline severity of illness, presence of psychotic symptoms, drug-naive status, stimulus dose, seizure duration, seizure strength, pattern and symmetry, frequency of ECT and degree of improvement predicted the delta PRL response. Neither stimulus energy nor frequency of ECT had a significant effect on PRL response. Gender differences in PRL response to ECT merit further investigations.