Systematic review of tactile-based interventions combined with multisensory stimulation protocols in the...

Social touch interventions have the potential to modulate psychological and physiological stress in intensive care settings. In individuals with disorders of consciousness (DOC), tactile stimulation combined with other sensory modalities, (e.g., visual, auditory, olfactory, gustatory, and proprioceptive), has been proposed to enhance arousal, behavioural responsiveness, and recovery, while mitigating sensory deprivation. However, tactile stimulation encompasses heterogeneous forms of touch and the extent to which clinical benefits can be attributed to specific tactile qualities remains unclear. Here, we conducted a systematic review following PRISMA guidelines to examine the effects of tactile-based multisensory stimulation protocols on behavioural and physiological indicators of consciousness in adults with DOC. Overall, the reviewed studies suggest that tactile stimulation, particularly when embedded within multisensory and emotionally salient contexts, can elicit measurable changes in consciousness-related outcomes. However, substantial methodological heterogeneity, including variability in stimulation protocols, outcome measures, control conditions, and patient characteristics, limits the strength of causal inferences and clinical generalisability. Drawing on social touch and interoception research, we discuss how interpersonal touch may engage body-referential, autonomic, and affective processes that are plausibly preserved in DOC. Specifically, we outline a theory-driven framework in which social touch, including but not limited to stimulation engaging C-tactile (CT) afferent pathways, is proposed as a promising avenue for future mechanistically informed interventions. We emphasise that this framework is forward-looking and requires direct empirical testing. Future studies should adopt standardised, well-controlled designs to disentangle tactile-specific effects, clarify underlying mechanisms, and optimise the therapeutic use of touch in DOC rehabilitation.