Immediate and long-term effects of transcranial direct current stimulation on pain relief in older adults with Alzheimer's disease and related dementias: A pilot study.

We simultaneously assessed the impact of transcranial direct current stimulation (tDCS) on mitigating both self-reported pain and pain behaviors to more objectively explore its effects in older adults with Alzheimer's disease and related dementias. The analysis investigated 40 participants randomly (1:1) subjected to active and sham tDCS for 20 min on 5 consecutive days. Multi-group latent transition analysis enabled the simultaneous evaluation of both pain domains in a single model and analysis of their changes as a function of intervention exposure by modeling the transition probabilities of latent classes and comparing these changes between groups. Two pain categories ("high pain" and "low pain") were identified based on the numeric rating scale and mobilization-observation-behavior-intensity-dementia scale scores. Overall, tDCS demonstrated better effects in helping participants transition to a "low pain" status during and after the intervention (∼3 months) compared with sham stimulation, demonstrating its immediate and enduring effects.