Fumie Tazaki

Horticultural therapy is widely used in geriatric care, yet the neurophysiological mechanisms distinguishing natural from artificial plant materials remain inadequately characterized. This within-subject crossover study examined electroencephalographic (EEG) source activity and heart rate variability (HRV) in 29 community-dwelling elderly women (mean age, 77.66 ± 3.71 years) during flower arrangement (FA) tasks using fresh and artificial flowers. A subset of 16 women (mean age, 78.13 ± 3.30 years) provided sufficient artifact-free HRV data. EEG source localization using exact low-resolution electromagnetic tomography (eLORETA) with statistical nonparametric mapping revealed a significantly greater current source density in the left frontal lobe delta band (2–4 Hz) during fresh vs. artificial FA, localized at the Montreal Neurological Institute coordinates (X, Y, Z) = (–20, 60, 25 mm). The fresh-flower condition also elicited significantly higher cardiac vagal index values [3.44 ± 0.26 vs. 3.32 ± 0.29; t (15) = 2.659, P = 0.018, Cohen’s d = 0.665], indicating a medium-to-large effect on parasympathetic activity. No significant difference appeared in the cardiac sympathetic index [ t (15) = –0.415, P = 0.684, d = –0.104]. Although frontal delta enhancement during tasks is traditionally associated with drowsiness or reduced cortical efficiency, converging evidence suggests context-dependent roles in homeostatic and motivational processes. The left-sided localization is a pattern that has been associated with approach-related neural systems in the alpha-band literature, although extrapolation to delta oscillations remains speculative. This finding may suggest the possible engagement of motivational processing alongside parasympathetic relaxation, but alternative interpretations, including mild hypoarousal, cannot be excluded. These findings are consistent with but do not uniquely confirm the biophilia hypothesis or approach motivation, and alternative interpretations including mild hypoarousal remain plausible. Nonetheless, the results provide preliminary neurophysiological corroboration for the therapeutic value of authentic botanical materials in horticultural interventions for elderly populations.

Chronic pain may impede occupational participation in older adults, but links among mobility, social networks, cognitive function, and pain-related factors remain unclear. To examine the relationships among these factors in relation to occupational participation in community-dwelling older Japanese adults. In this cross-sectional study, 130 adults more than 60 answered questions about occupational participation, mobility, social networks, cognitive function, and pain. Exploratory factor analysis was used to extract latent variables representing key constructs. These were incorporated into structural equation modeling to examine their associations with occupational participation. Latent factors combining mobility and social networks (standardized coefficient: 0.75), and cognitive functions (0.35), were directly and positively associated with occupational participation, while pain-related factors were strongly negatively correlated with mobility/social networks (-0.79, -0.73) but showed no direct association with participation. Interventions addressing both physical and social function and pain-related barriers may support occupational participation in older adults.