Title:Outcomes and Factors Affecting Transcranial Direct Current Stimulation
in Alzheimer's Disease Patients: A Systematic Review
Volume: 20
Issue: 4
Author(s): Rabeet Tariq*, Bhavya Kansal*, Rameen Shaikh, Shria Datta, Harsh Anadkat and Seema Bista
Affiliation:
- Department of Neurosurgery, Liaquat National Hospital and Medical College, Karachi, Pakistan
- Lady Hardinge
Medical College, Delhi, India
Keywords:
Neuromodulation, Alzheimer’s disease, transcranial direct current stimulation, neurodegeneration, memory, neuropsychological effects.
Abstract:
Introduction: Alzheimer's disease (AD) is the most common form of dementia. There have
been various proposed pharmacologic and non-pharmacologic treatments proposed for preventing
cognitive decline in AD patients. Transcranial Direct Current Stimulation (tDCS) is a neuromodulation
technique used to enhance cognitive functions and motor skills of the brain. Our study aimed to
assess the effects of tDCS in AD patients, including effects on general cognitive status, memory, attention,
executive functions, language, IQ, and neuropsychological effects, along with the factors influencing
the outcomes.
Methods: Systematic searches were conducted for relevant evidence using PubMed, ScienceDirect,
and Cochrane Library databases for (Transcranial Direct Current Stimulation) and (Alzheimer’s). Duplicates
were removed, and the remaining articles were screened for double-blind, placebo-controlled,
randomized clinical trials (Phase III), case studies, and case series on patients diagnosed with AD using
tDCS. The articles were assessed for full text, and studies were selected and analyzed to include in
the review.
Results: Overall, 20 studies were reviewed. Cognitive status, executive function and working
memory, recognition memory, and language function may improve following AtDCS depending on
the stimulation polarity and area stimulated. No significant effects of tDCS were seen on attention,
associative memory, recall memory, visuospatial ability, and neuropsychiatric symptoms.
Discussion: Therapy outcomes and the factors that could affect them were analyzed, which included
the number of sessions taken, current density, stimulation polarity (cathodal/anodal/dual), area stimulated,
training(s) given, and study timeline.
Conclusion: tDCS is a well-tolerated therapy that can be used for improving several cognitive domains
in patients having Alzheimer’s disease. Its treatment outcomes are affected by polarity (cathodal/
anodal), site of stimulation, number of sessions taken, and any training(s) given during the study.