P166. Polymorphism of the brain derived neurotrophic factor and electroconvulsive therapy

Abstract

Objective Patients repeatedly receiving electroconvulsive therapy (ECT) for difficult to treat psychiatric diseases often may require either constant – and then frequently low – stimulation currents in order to induce a seizure or they will receive stimulus currents that need to be increased step-wise often reaching the maximum-stimulator output at some point during a series of ECTs. Results of recent research suggests that a polymorphism of the brain-derived neurotrophic factor (BDNF) affects cerebral plasticity ( Cheeran et al., 2008 ). We investigated weather a common polymorphism of the BDNF influences the change in threshold-currents of brain stimulation by electroconvulsive therapy (ECT). Methods 21 patients (mean age 53.29 ± 14.51a, 10 women) who received at least 12 single ECTs for the first time or repeat-ECT starting with a new baseline-threshold-value for the treatment of major depression or schizophrenia were included into the study. Stimulation was performed with a Thymatron DGx® or Thymatron System IV® stimulator. Electrodes were placed in a left anterior to right temporal (LART) montage with bitemporal montages being used in cases of insufficient seizure duration with the LART-montage. The stimulation threshold generally corresponded to the patients’ age including values of not less than 20% and no more than 60% of maximum stimulator output being adjusted to the patients’ age in increments of 5%. Current intensities were increased in increments of 10–80% based on the decision of the person conducting the ECT after those EEG- or motor-seizure with a duration of less than 25 s. Genetic testing for a common polymorphism of the BDNF regarding the type of the 66th amino-acid of the molecule was performed testing for the allele-status with either both alleles coding for the amino-acid valine (Val/Val) or one coding for valine with the other coding for methionine (Val/Met). Paired two-tailed t-tests were performed for comparison of ECT-stimulation currents. Results Genetic testing revealed that the allele-status of 12 patients (mean age 53.92 ± 13.26a, 5 women) was Val/Val while 9 patients (mean age 52.44 ± 16.94a, 5 women) had the so called Val/Met-polymorphism. However, the current intensities used in both groups did not differ significantly when comparing corresponding ECT time points between both groups (p-values > 0.5). Standard deviations in both groups were high. Conclusion While the conclusion is limited by the small sample-number the Val/Val- and Val/Met-BDNF-polymorphism at codon 66 appears not to be explanatory for the different course of within-patient stimulation currents needed to induce seizures during a series of ECTs.