Transcranial direct current stimulation neuromodulation in elderly individuals and its impact on anxiety and depression symptoms

Abstract

To evaluate the effects of anodal transcranial direct current stimulation (tDCS) over the left prefrontal cortex, combined with computerized cognitive training, on cognitive performance, anxiety, depression, motor reaction time, and neurophysiological markers in elderly women with subjective cognitive decline or preserved cognition.

Methods This was a randomized double-blind clinical trial involving 30 elderly women allocated to three groups: active tDCS, sham tDCS, and controls. The intervention consisted of nine sessions of tDCS combined with cognitive training. Cognitive aspects (Addenbrooke's Cognitive Examination-Revised), depressive symptoms (CES-D), anxiety symptoms (GAI), motor reaction times, and neurophysiological aspects (EEG) were assessed. Statistical analyses included ANOVA and paired t-tests for between-group comparisons.

Results The tDCS group exhibited significant improvements in global cognition, episodic memory, verbal fluency, and language. Additionally, there was a significant reduction in anxiety and depression scores compared to those in the sham and control groups. The motor reaction time was reduced in the tDCS group, indicating improved sensorimotor integration. The EEG data demonstrated increased cortical excitation and improved emotional valence in the tDCS group.

Conclusion Anodal tDCS associated with computerized cognitive training has proven to be an effective strategy for optimizing performance in memory tasks, verbal fluency, and decision-making as well as for reducing anxiety and depression symptoms in elderly individuals with or without subjective cognitive decline. Based on these findings, tDCS is a promising and safe tool for developing cognitive interventions for the elderly. Future studies should explore the long-term effects and impact of different stimulation protocols.