Transcranial electric stimulation in chronic pain: Effects on quality of life, physical function, activity and clinical status

Transcranial electric stimulation represents a promising non-invasive neuromodulatory technique targeting maladaptive nociplastic changes in chronic pain (CP) with analgesic effects. However, its impact beyond pain reduction on broader outcomes such as quality of life (QoL) and physical function remains unclear. This study aimed to evaluate the impact of two home-based transcranial electric stimulation modalities, using direct (tDCS) or alternating current (tACS), on improving QoL, addressing comorbid symptoms and enhancing physical function and engagement in physical activity in individuals with CP. In a double-blind randomized controlled trial, 120 CP participants (97 females, 49.5 ± 8.7 years) received 15 sessions of home-based tDCS over the primary motor cortex (M1), tACS over the dorsolateral prefrontal cortex (DLPFC), or sham stimulation. A multidimensional assessment was used before, during and after the treatment, combining subjective measures (QoL, mood, fatigue, sleep quality, perceived physical fitness) and objective metrics (field-based physical fitness tests, accelerometry). Compared with the sham group, both active tES modalities significantly improved QoL, with no differences between M1-tDCS (MD=-7.7; p < .001) and DLPFC-tACS (MD=-7.8; p < .001). However, symptom-specific domains showed no differential effects compared with sham (all p > .05). All groups exhibited increased physical activity during the intervention and improvements in physical function after the intervention (p < .001), suggesting the contribution of contextual factors. Our findings highlight the potential of home-based tES to enhance QoL in CP patients. The lack of differences between intervention groups in domain-specific outcomes (mood, fatigue, sleep) and physical activity underscores the complexity of the therapeutic response, likely influenced by neurophysiological, behavioural, and contextual mechanisms.