Health in your hands: Multi-method insights into the physiological and psychological outcomes of real and vicarious interpersonal touch in older adults

Interpersonal touch is recognised for its comforting effects, promoting both health and well-being, and aiding in stress regulation. However, most research on touch has focused on younger adults and single health markers, leaving considerable gaps in understanding the impact of touch for multi-systemic health, especially in groups at risk of touch absence. In this thesis, four studies investigate the health benefits of interpersonal touch for older adults, including the factors that may be most important and the role of a vicarious touch as a possible intervention. Findings from the National Social Life, Health, and Aging Project (NSHAP) found that frequent touch with romantic partners was associated with improved neuroendocrine health in cross-sectional analyses and better metabolic and cardiovascular health in longitudinal analyses. In contrast, touch with other close individuals showed no comparable associations. In examining vicarious hugs, we observed that while longer durations of observation increased autonomic arousal, indicated by pupil dilations, they did not protect from stress. Furthermore, different types of touch, including CT-optimal stroking, hugging, and handshakes, shared with individuals of varying emotional closeness (close individual, stranger, and vicarious) were associated with varying physiological and neural responses. CT-optimal stroking showed the most context-independent reductions in heart rate and increased in theta power. Overall, neural findings suggest that theta oscillatory increases may be a marker of both tactile observation and sensation in older adults, while beta and alpha are responsible for differences in attentional processing, but also the hedonic properties of touch in older adults. These insights could be used to support public health strategies aimed at improving physiological well-being in older adults, with further scope for the use of vicarious stroking as a low-cost intervention for older adults in social care or clinical settings.