Repeated ECT and prolactin release in depressed patients

Prolactin changes during electroconvulsive therapy: A systematic review and meta-analysis

BACKGROUND

Early studies reported a prolactin surge during electroconvulsive therapy (ECT). The aim of this study is to review and meta-analyze data on ECT-related prolactin changes.

METHOD

A systematic review and meta-analysis was conducted for trials investigating prolactin changes in ECT-treated patients using standard mean differences (SMD, 95% confidence intervals). Subgroup analyses included comparisons of ECT-related prolactin changes in women vs. men, patients receiving different anesthetics, bilateral vs. unilateral and high-vs. low-dose ECT.

RESULTS

In six trials including 109 ECT-treated patients and 74 controls, prolactin changes were larger in ECT-treated patients than in controls (SMD = 0.89, 95%CI = 0.55, 1.23, p < 0.001 and 1.03, 95%CI = 0.31, 1.75, p = 0.005 for the fixed and random-effect model respectively), despite heterogeneity in the samples (I² = 72%, τ² = 0.62). Effects were led by differences in patients premedicated with methohexital (SMD = 1.14, 95%CI = 0.7, 1.57, p < 0.001 for both fixed and random-effect model). A meta-regression reported significant age effects (coefficient estimate 2.32, 95%CI = -0.73, 3.91, p < 0.01). Additionally, prolactin changes were larger in ECT-treated women than men (SMD = 0.88, 95%CI = 0.58, 1.18, p < 0.001 and 0.99, 95%CI = 0.22, 1.75, p = 0.012 for the fixed and random effect model). Bilateral ECT-treated patients had larger increase than unilateral ECT-treated patients (SMD = -0.81, 95%CI = -1.35, -0.27, p = 0.003 and -0.86, 95%CI = -1.46, -0.25, p = 0.006 for the fixed and random-effect model). Comparisons between high- and low-dose ECT-treated patients could not be conducted. The quality of the studies was overall poor, with four exceptions.

DISCUSSION

Patients receiving ECT had larger prolactin increases than controls. Increases were larger in methohexital-premedicated patients, women vs. men and patients with bilateral vs. unilateral ECT.

Gender but not stimulus parameters influence prolactin response to electroconvulsive therapy

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.

Effect of ECT treatment number on the ictal EEG

Recent evidence suggests that attributes of the ictal electroencephalogram (EEG) may be clinically useful for estimating the extent to which the electroconvulsive therapy (ECT) stimulus exceeds the seizure threshold (relative stimulus intensity). Such a tool could allow a practitioner, who chose, on the basis of expected therapeutic response and side effect rates, to implement stimulus dosing to maintain relative stimulus intensity over the treatment course, despite the uncertain rise in seizure threshold that occurs. One potential confounding factor is a possible systematic change in the ictal EEG over the treatment course that is not due to changes in seizure threshold. We explored the effect of treatment number by comparing ictal EEG data obtained at treatments across the ECT course that were delivered at the identical relative stimulus intensity. We found that the ictal EEG at treatment 1 was characterized by a greater mid-ictal amplitude and post-ictal suppression (trend) than subsequent treatments for barely suprathreshold unilateral ECT, but not for barely suprathreshold bilateral or moderately suprathreshold unilateral ECT, and that this change may affect therapeutic effectiveness. These findings suggest the importance of treatment-number effects for the clinical application of the ictal EEG and point to possible physiological differences between unilateral and bilateral ECT.