Horticulture therapy affected the mental status, sleep quality, and salivary markers of mucosal immunity in an elderly population

Horticultural therapy (HT) has been reported to be beneficial to mental and physical health. This study investigated the effects of HT on the psychological status and mucosal immunity of elderly individuals. Twenty-four participants aged 70–93 were recruited from residential facilities and adult day-care services. Six different HT activities were designed and guided by licensed instructors who performed saliva collection and helped the participants complete the questionnaires before and after each activity. The sleep quality scores were collected during the 6 weeks of HT activities. Saliva was collected and analyzed to determine the concentrations of immunoglobulin A (IgA), lactoferrin, chromogranin A (CgA), α-amylase (AA) and total protein (TP). Comparisons of the questionnaire scores between preactivity and postactivity showed that feelings of satisfaction and happiness were significantly enhanced after each activity. In addition, sleep quality was significantly improved after the 6-week course of HT activities. Regarding mucosal immunity, the preactivity IgA and IgA/TP were significantly increased at week 3 and week 6; in addition, the ratio of lactoferrin/TP was significantly decreased at week 6 compared to week 1. The postactivity AA and CgA levels were significantly enhanced at weeks 2, 3 and 5 compared to the corresponding preactivity levels. In conclusions, HT activities significantly improved the happiness, satisfaction, well-being and sleep quality of the elderly. Moreover, mucosal immunity proteins, including IgA, lactoferrin, CgA and AA, were significantly increased.