To study the effects of transcranial direct current stimulation on executive function in people with mild to moderate dementia

Extensive research had shown executive dysfunction in people with dementia (PWD) is associated with functional abnormalities in prefrontal regions such as the right inferior frontal gyrus (Right IFG) or the left dorsal lateral pre-frontal cortex (Left DLPFC) . Clinical studies suggest that tDCS may be a useful therapeutic tool. Post-tDCS improvements have also been shown in visuo-motor coordination of healthy controls and performance in working memory. The aim of this study is to investigate the effect of tDCS stimulation over left DLPFC or right IFG on attention, inhibition and working memory and their neural correlates in people with dementia (PWD) and healthy controls (HC).This study is planned as a double-blinded, randomized case-control interventional study with a duration of 30 months.

Inclusion Criteria:

• PWD must be aged at least 65 years or above when informed consent is obtained in the presence of his / her first degree relatives.
• PWD must meet criteria of DSM-V for dementia as well as for historical diagnosis of dementia.
• PWD must have a Chinese MoCA score > 19 (mild to moderate cognitive deficits) at screening.
• Subjects (both PWD and HC) must be physically healthy, and must be able to understand and be willing to sign the informed consent document

Exclusion Criteria:

• Subject with major neurological illness.
• Subject with other diagnosed psychiatric disorders
• Subjects reported with history of substance abuse, which including alcohol, drugs or any medication which is indicative of chronic abuse.
• Failures to comply with the study protocol or to follow the instructions.
• Self-reported with known skin diseases or skin allergy history.
• Self-reported with metallic implants, dentures
• Self-reported with history of claustrophobia. (This is excluded because subject needs to stay in a quiet room with the head-mounted fNIRS and tDCS, which may elicit their feeling of anxiety)

double-blinded, with randomized case-control