Facilitative effects of bi-hemispheric tDCS in cognitive deficits of Parkinson Disease patients

Parkinson’s disease (PD) is a progressive neurodegenerative disorder, primarily characterized by motor
symptoms such as tremor, rigidity, bradykinesia, stiffness, slowness and impaired equilibrium.
Although the motor symptoms have been the focus in PD, slight cognitive deficits are commonly found
in non-demented and non-depressed PD patients, even in early stages of the disease, which have been
linked to the subsequent development of pathological dementia. Thus, strongly reducing the quality of
life (QoL).
Both levodopa therapy and deep brain stimulation (DBS) have yield controversial results concerning
the cognitive symptoms amelioration in PD patients. That does not seems to be the case with transcranial
direct current stimulation (tDCS), although better stimulation parameters are needed. Therefore we
hypothesize that simultaneously delivering cathodal tDCS (or ctDCS), over the right prefrontal cortex
delivered with anodal tDCS (or atDCS) to left prefrontal cortex could be potentially beneficial for PD
patients, either by mechanisms of homeostatic plasticity and by increases in the extracellular dopamine
levels over the striatum.
This work was supported by the Portuguese Foundation for Science
and Technology with individual Grants (SFRH/BPD/86027/
2012) and (SFRH/BPD/86041/2012). The sponsors had no role in
the establishment of the present hypothesis