The road towards personalized medicine: Increasing the effects of brain stimulation using individual characteristics

Abstract

Non-invasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have shown high treatment potential for a broad variety of neuropsychiatric disorders. However, the application of ‘standard’ protocols results in high inter-individual differences in the responses and reduce the overall efficacy. In this symposium, individual characteristics that are linked to the clinical outcome of stimulation treatment will be highlighted. It can be hypothesized that inter-individual differences in responses to stimulation can be assigned to variations in individual neurocircuitries. Therefore, the first two presentations will focus on functional connectivities (FC) on network level. Firstly, the use of graph analysis to study the effect of accelerated intermittent theta burst stimulation (aiTBS) is explained (n = 50, major depressive disorder patients). Also it will be shown that baseline graph measures can predict the clinical efficacy of this stimulation protocol. Clinical efficacy in this case was derived from the 17-item Hamilton questionnaire. Secondly, the influence of different stimulation positions, derived from FC within two different networks, on the effect of one iTBS session on an n-back task will be presented (n = 12, healthy subjects). Being more or less vulnerable to psychopathology can also affect the outcome of NIBS. For example, the tendency to ruminate in daily life influences the outcome of iTBS (n = 38, healthy subjects). Here, the effect of iTBS was quantified using cortisol recovery. Moreover, the application of prefrontal tDCS before listening to self-referent criticism affects FC between the left dorsal anterior cingulate cortex and the right dorsomedial prefrontal cortex distinctively in healthy women low versus high in perceived criticism (n = 46). In conclusion, this symposium will show that individual mechanisms play a role in the effect of NIBS. Therefore, in future protocols, personalized characteristics might enhance clinical efficacy.