Impact of Transcranial Direct Current Stimulation on Language Functions in Mild Cognitive Impairment (STIMCI)

Impact of Transcranial Direct Current Stimulation on Language Functions in Mild Cognitive Impairment: A Proof-of-principle Study and Neural Correlates

The purpose of this study is to determine if non-invasive electrical brain stimulation can improve word-retrieval in Mild Cognitive Impairment (MCI).

Previous studies showed that anodal transcranial direct current stimulation (atDCS) can have beneficial effects on word-retrieval in healthy younger and older subjects. The present study aims to extend these findings by assessing whether atDCS can also improve known impairments of word-retrieval in Mild Cognitive Impairment. atDCS will be applied to the left inferior frontal gyrus in a sham controlled cross-over within subjects design. Simultaneous functional magnetic resonance imaging (fMRI) will assess underlying neural effects of the stimulation.

anodal tDCS will be administered for 20 minutes with 1 milliampere (1 mA) to the left inferior frontal gyrus

anodal tDCS will be delivered with a constant current of 1 mA during resting-state and task-related fMRI and will continue until the end of the word-generation task. For both stimulation conditions (atDCS, sham) the current will be initially increased in a ramp-like fashion over 10 s, eliciting a tingling sensation on the scalp that fades over seconds. During sham stimulation the current will be turned off after 30 s.

Subjects are assessed in a cross-over design. The primary outcome measure will be assessed twice in each subject, either during sham stimulation or active stimulation with transcranial direct current stimulation. Order of stimulation (sham, atDCS or atDCS, sham) will be counterbalanced across the group. The study design has been described in detail before (Meinzer et al., 2012, Journal of Neuroscience, 32:1859 -1866).

Change in number of correct responses between Assessment 1 (week 1) and Assessment 2 (week 2), assessments 1 and 2 are seperated by one week

Change in fMRI activity between Assessment 1 (week 1) and Assessment 2 (week 2), assessments 1 and 2 are seperated by one week

Inclusion Criteria: right handed German native speakers clinical diagnosis of Mild Cognitive Impairment Exclusion Criteria: dementia other current or previous neurological or current psychiatric diseases alcohol or drug abuse MRI contraindication (e.g., magnetic metal, pacemaker, claustrophobia