Transcranial Electric Current Stimulation During Associative Memory Encoding: Comparing tACS and tDCS Effects in...

Area of Science:

• Neuroscience
• Cognitive Psychology
• Gerontology

Background:

• Associative memory declines with aging, impacting daily function.
• Non-invasive brain stimulation (NIBS) offers potential memory support for older adults.
• Optimal NIBS parameters for enhancing memory in older populations are not well-established.

Purpose of the Study:

• To investigate the effects of anodal transcranial direct current stimulation (tDCS) and theta-range alternating current stimulation (tACS) on associative memory in healthy older adults.
• To compare the efficacy of tDCS and tACS against sham stimulation for memory performance.

Main Methods:

• A randomized, double-blind, cross-over study involving 28 healthy older adults (mean age ~71 years).
• Participants received anodal tDCS, tACS, or sham stimulation over the left ventrolateral prefrontal cortex (VLPFC) during memory encoding.
• Associative memory was assessed using cued recall and recognition tasks post-retention and on the following day.

Main Results:

• Neither tDCS nor tACS demonstrated significant overall effects on associative memory performance.
• A significant improvement in cued recall performance was observed under tACS compared to sham stimulation when age was considered.
• Results suggest tACS may be more effective than tDCS for improving associative memory in older individuals.

Conclusions:

• Current NIBS protocols may not universally enhance associative memory in healthy older adults.
• Theta-range alternating current stimulation (tACS) shows promise for improving specific aspects of memory, particularly cued recall, in older age groups.
• Further research is needed to optimize tACS parameters for targeted memory enhancement in aging populations.