Probing neuroprotective effects of single session rTMS on subsequent mood and emotional processing

In spite of a wide variety of treatment options, the prognosis of major
depression is still poor: chronicity affects at least a third of patients and
relapses are common. Optimisation of existing treatment strategies are urgently
needed.Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral
prefrontal cortex (DLPFC) has been introduced more than a decade ago as an
antidepressive treatment option, but its acute effects on mood and cognitive
functioning remain unclear. Furthermore, it remains unknown whether rTMS can
have neuroprotective effects that prevents relapse during remission.By inducing
an electric current in the TMS coil, a magnetic field is created leading to the
induction of a secondary electric current in the stimulated brain area (for an
extended description see, Schutter, 2011)
. Depending on the frequency by which a magnetic pulse is emitted, a
stimulation or inhibition on a neuronal level is induced (Siebner & Rothwell,
2003), which effects can last longer than the stimulation itself, if applied
over an extended period of time (Hallett, 2007). In this way, high frequency
(10Hz or faster) stimulation lasting several minutes can enhance the
excitability of the stimulated area for a prolonged period of time (Fitzgerald
et al., 2006; Schutter, 2009) therefore likely to change not only mood but also
attentional biases that are thought to play a causal role in onset and
maintenance of depression. While clinical research is ongoing, testing more
standardized forms of rTMS treatment in a randomized controlled trial set-up,
more fundamental knowledge is also needed to investigate the potential
neuroprotective effects of rTMS. May it be useful in the future to weaken the
effects of external factors by influencing mood resilience in subjects.

To examine the protective effects of a single session of high frequency rTMS
over the left dorsolateral prefrontal cortex on negative mood and motivated
attention.

In the present sham-controlled crossover study a single session of active and
sham high frequency rTMS will be applied to the left dorsolateral prefrontal
cortex in healthy volunteers. A validated sad mood induction procedure will be
applied after rTMS to measure its mood protective effects. Furthermore, the
effects on motivated attention and resting state electric brain activity (EEG)
will be assessed.

All 24 participants will experience the rTMS treatment. Once real rTMS and once
sham-rTMS, both will take 30 minutes. The two intervention sessions will be
separated by at least 1 week with a maximum of four weeks.

All measurements will be administered during two visits of 2 hrs at our
outpatient depression unit. The actual rTMS treatment will take about 30
minutes. Except for financial compensation or course credit points, possible
benefit resulting from the treatment cannot be guaranteed to participants.
Transcranial magnetic stimulation (TMS) is a widely used non-invasive brain
stimulation technique, based on the principle of electromagnetic induction.
During stimulation the participant will likely hear the clicks of the TMS
pulses and experience stimulation of nerves and muscles of the head. The most
common side effect is a light transient headache (2-4% occurrence). A severe
headache is uncommon (0.3-0.5% occurrence). In the current study healthy
participants will be stimulated with a protocol that falls within the safety
guidelines. All participants are screened for their relevant medical history
and other TMS safety aspects (e.g. presence of metal parts in the head). There
are no risk factors related to the computerized attention training. There is no
direct benefit for the participants. The study will broaden our understanding
of how rTMS influences mood and cognition that may have clinical implications.