engleski

Interaction of serotonin and age is significant predictor of transcranial magnetic stimulation effect on major depressive disorder: a prospective cohort study in Croatia

Introduction: Serotonin plays an important role in mood control. It is one of the two primary antidepressants’ targets. However, previous studies have not found the baseline serotonin level to be a significant predictor of TMS effects on major depressive disorder (MDD). One of the explanations was that plasma concentrations may have limited validity for the brain serotonin levels. Objective: We hypothesized that previous studies failed to detect serotonin predictive value because they missed to analyze some important moderators or control the effect of some important confounders. We hypothesized that such moderators may be: age, sex, duration and severity of MDD. Methods: This cohort study was conducted at Psychiatric Hospital Sveti Ivan, Zagreb, Croatia during 2016/2017, on the sample of patients diagnosed with MDD. The outcome was Beck Depression Inventory-II (BDI-II) result after 4-week treatment with TMS, adjusted for BDI-II baseline result. Moderators values defining Johnson–Neyman significance regions were analyzed in PROCESS Release 1.16.2, written by Andrew F. Hayes. Results: We enrolled the sample of 37 patients. The overall model including age, serotonin, and their interaction significantly predicted BDI-II change (R2 = 0.52 ; p = 0.006). Interaction of baseline serotonin concentration and age was significant predictor by itself (R2 = 0.29 ; p = 0.003). Serotonin was a significant predictor of TMS effects in patients younger than 35, and older than 51. In younger patients, higher baseline serotonin levels were associated with higher BDI-II results at fourth week indicating lower efficacy of TMS treatment. In older patients, this effect was reversed. Interactions of serotonin and other hypothesized moderators were not significant predictors of BDI-II change. Conclusion: Baseline serotonin level prediction value for TMS effects on MDD is moderated by patients’ age. If serotonin is analyzed alone, it is not significantly associated with TMS treatment outcome, as its effects in lower and higher age groups are reversed and they mutter.

latelet serotonine ; transcranial magnetic stimulation ; depression

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