Effects of Psychotropic Drugs on Seizure Threshold during Electroconvulsive Therapy

OBJECTIVE: To analyze the relationship between seizure threshold (ST) and psychotropic drugs in patients treated with ECT. METHODS: We examined clinical data from 43 patients. ST was titrated at each treatment session. We examined associations between ST and psychotropic drugs using multivariate correlation analyses. Data are presented as initial ST, the difference in ST between the first and 10th sessions (ΔST(10th)), and the mean difference in ST between the first and last sessions (mean ΔST(last)). RESULTS: Multivariate regression analyses showed associations between initial ST and the total chlorpromazine-equivalent dose of antipsychotics (β=0.363, p<0.05). The total fluoxetine-equivalent dose of antidepressants was associated with ΔST(10th) (β=0.486, p<0.01) and mean ΔST(last) (β=0.472, p<0.01). CONCLUSION: Our study elucidated possible effects of psychotropic drugs on ST shifts. Larger doses of antipsychotics were associated with higher initial ST, whereas higher doses of antidepressants were associated with stronger shifts in ST.