Ted Kheng Siang Ng1, Daniel R Y Gan2, Rathi Mahendran3, Ee Heok Kua4, Roger C-M Ho4. 1. Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block, 119228, Singapore. Electronic address: a0047115@u.nus.edu. 2. Real Estate Foundation Postdoctoral Fellow at the Gerontology Research Centre, Simon Fraser University, #2800-515 West Hastings St, Vancouver, B.C, V6B 5K3, Canada. 3. Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block, 119228, Singapore; Department of Psychological Medicine, National University Hospital, 1E Kent Ridge Road, NUHS Tower Block, 119228, Singapore; Academic Development Department, Duke-NUS Medical School, 8 College Road, Singapore. 4. Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block, 119228, Singapore; Department of Psychological Medicine, National University Hospital, 1E Kent Ridge Road, NUHS Tower Block, 119228, Singapore.
Abstract
BACKGROUND: Elevated levels of inflammatory marker and a lack of social connectedness are two prominent risk factors for developing dementia and depression. Horticultural therapy (HT) has been shown to improve social connectedness and inflammatory markers. However, the underpinning mechanisms of HT remained unknown. Within this study, we hypothesized that improved social connectedness mediates the effects of HT on IL-6 levels. METHODS: The present study is a secondary analysis of a randomized controlled trial investigating the bio-psycho-social effects of HT. Social connectedness was operationalized as positive relationships with others (PRWO), a sub-scale of the Ryff's scale of psychological well-being. IL-6 was quantified using a commercial ELISA kit. Outcomes were assessed at baseline, 3-month and 6-month post-intervention. Mediation analyses with bootstrapping were run to investigate our primary hypothesis. All analyses were controlled for covariates. RESULTS: We recruited 59 participants (78% women; 67.10 ± 4.31 years). 29 participants partook in HT and 30 participants were included in the waitlist control group. At baseline, social connectedness was significantly correlated with IL-6 levels (β = -0.12, 95% CI = -0.21 to -0.03, p = 0.008). Furthermore, social connectedness at 3-month significantly mediated the effects of HT on IL-6 levels at 6-month (β = 0.32, 95% CI = 0.09 to 0.54, p = 0.005; β = -0.25, 95% CI = -0.45 to -0.05, p = 0.016). CONCLUSIONS: These findings highlight the critical roles of social connectedness as a social determinant of health in eliciting HT's biological effects. When administering HT, interventionalists should consider social connectedness as a modifiable factor for ameliorating increased inflammation in older adults.
RCT Entities:
BACKGROUND: Elevated levels of inflammatory marker and a lack of social connectedness are two prominent risk factors for developing dementia and depression. Horticultural therapy (HT) has been shown to improve social connectedness and inflammatory markers. However, the underpinning mechanisms of HT remained unknown. Within this study, we hypothesized that improved social connectedness mediates the effects of HT on IL-6 levels. METHODS: The present study is a secondary analysis of a randomized controlled trial investigating the bio-psycho-social effects of HT. Social connectedness was operationalized as positive relationships with others (PRWO), a sub-scale of the Ryff's scale of psychological well-being. IL-6 was quantified using a commercial ELISA kit. Outcomes were assessed at baseline, 3-month and 6-month post-intervention. Mediation analyses with bootstrapping were run to investigate our primary hypothesis. All analyses were controlled for covariates. RESULTS: We recruited 59 participants (78% women; 67.10 ± 4.31 years). 29 participants partook in HT and 30 participants were included in the waitlist control group. At baseline, social connectedness was significantly correlated with IL-6 levels (β = -0.12, 95% CI = -0.21 to -0.03, p = 0.008). Furthermore, social connectedness at 3-month significantly mediated the effects of HT on IL-6 levels at 6-month (β = 0.32, 95% CI = 0.09 to 0.54, p = 0.005; β = -0.25, 95% CI = -0.45 to -0.05, p = 0.016). CONCLUSIONS: These findings highlight the critical roles of social connectedness as a social determinant of health in eliciting HT's biological effects. When administering HT, interventionalists should consider social connectedness as a modifiable factor for ameliorating increased inflammation in older adults.
Authors: Ted Kheng Siang Ng; Patricia C Heyn; Alex Tagawa; Christina Coughlan; James J Carollo Journal: Front Neurol Date: 2022-06-27 Impact factor: 4.086
Authors: Ted Kheng Siang Ng; David Bruce Matchar; Timothy V Pyrkov; Peter O Fedichev; Angelique Wei-Ming Chan; Brian Kennedy Journal: Aging (Albany NY) Date: 2021-08-29 Impact factor: 5.682
Authors: Daniel R Y Gan; Grand H-L Cheng; Tze Pin Ng; Xinyi Gwee; Chang Yuan Soh; John Chye Fung; Im Sik Cho Journal: Int J Environ Res Public Health Date: 2022-03-20 Impact factor: 3.390