Humanitas: Indonesian Psychological Journal Vol. 19 (1), February 2022, 23-30 ISSN: 2598-6368(online); 1693-7236(print) humanitas@psy.uad.ac.id http://dx.doi.org/10.26555/humanitas.v19i1.10 Hand grip strength and depression among rural older South Africans Karl Peltzer1,2 1Department of Psychology, Asia University, Taiwan 2Department of Research Administration and Development, University of Limpopo, South Africa Corresponding author: kfpeltzer@gmail.com Introduction Depressive disorders, with a prevalence of 12.1% depressive symptoms, are contributing to a large extent to the worldwide disease burden, including in lower-resourced countries (Ferrari et al., 2013). In nationally representative surveys in South Africa, 9.7% of the population reported major depression in their lifetime (Tomlinson et al., 2009), and about a third of older adults (≥65 years) had depressive symptoms (CES-D scores ≥ 10) (Tomita & Burns, 2013). To deal with the high burden of depression in later life, it has been suggested, in addition to treatment, to decrease the onset of depressive disorder in the community (Almeida, 2012; Whyte & Rovner, 2006). In this context, it would be important if, for example, muscle strength contributes to developing or maintaining depressive symptoms. Muscle strength can be objectively measured through handgrip strength (HGS) (Ashdown-Franks et al., 2019). HGS assessed during middle-age in population-based studies has been shown to predict mortality in older age (Buckner et al., 2019). A recent review of eight prospective studies (1 in China and 7 in high-income countries) found that low HGS increases the odds of depressive symptoms among men but not women (Huang et al., 2021). A prospective study among ageing adults in Ireland showed that HGS was inversely associated with incident depression among females but not males (McDowell et al., 2018). Additional studies are needed to investigate these sex differences (Huang et al., 2021). Furthermore, several studies also found a positive association between lower HGS and persistent depression (Carvalho et al., 2021). However, ART ICLE INFO AB ST R ACT Article history Received January 21, 2022 Revised February 4, 2022 Accepted February 10, 2022 The study aimed to assess the relationship between hand grip strength (HGS) and depressive symptoms among ageing women and men in a longitudinal study in rural South Africa. We analyzed longitudinal data from two consecutive population-based surveys in Agincourt, South Africa, 2014/2015-2018/2019. Results indicate that in all, 835 adults of 3268 participants without depression in Wave 1 (25.0 percent) had incident depression in Wave 2, and 184 adults of 3866 participants who had depression in Wave 1 (4.8 percent) screened positive for depression at both Wave 1 and 2 (persistent depression). The prevalence of weak HGS was 51.5 percent at baseline. In the fully adjusted model, weak HGS increased the odds of incident depressive symptoms between both sexes (AOR: 1.24, 95 percent CI: 1.04-1.47) among women (AOR: 1.33, 95 percent CI: 1.05-1.68), but not among men. No models among both sexes, among men and women, showed an increased odds of weak HGS with persistent depressive symptoms. Weak HGS was independently associated with the incident, but not persistent depressive symptoms between the two sexes and between women but not between men. Keywords hand grip strength; longitudinal study; persistent depression; South Africa. mailto:humanitas@psy.uad.ac.id http://dx.doi.org/10.26555/humanitas.v19i1.10 mailto:kfpeltzer@gmail.com 24 ISSN 2598-6368 (online) / ISSN 1693-7236 (print) Peltzer (Hand grip strength and depression among rural older South Africans) the relationship between HGS and incident and persistent depressive symptoms in Africa has not been researched. Consequently, the study aimed to assess the relationship between HGS and incident and persistent depressive symptoms among men and women in a longitudinal study in South Africa. Method Participants We analyzed longitudinal data from two consecutive population-based surveys (HAALSI) in Agincourt, South Africa. Full information on the sampling methodology has been reported previously (Gómez-Olivé et al., 2018). The first survey (November 2014 to November 2015) included 5,059 individuals (≥40 years), with a response rate of 86% (Gómez-Olivé et al., 2018), and the second survey (October 2018 to November 2019) included 4,176 members of the Wave 1 HAALSI cohort (595 died during follow-up: 12%, 254 declined participation: 5%, 34 were not found: <1%, and response rate: 94%) (Kobayashi et al., 2021a). Procedures The study was conducted by trained field workers at the homes of the participants after written informed consent was provided. The study was approved by the “University of the Witwatersrand Human Research Ethics Committee (ref. M141159), the Harvard T.H. Chan School of Public Health, Office of Human Research Administration (ref. C13–1608–02), and the Mpumalanga Provincial Research and Ethics Committee” (Gómez-Olivé et al., 2018). Instruments Outcome variable In the first and second survey depressive symptoms were assessed with the “Center for Epidemiological Studies-Depression Scale eight-item scale (CES-D 8)” (Radloff, 1977) or CES-D 20 modified to CES-D 8 (Steffick, 2000), (Cronbach’s alpha .66 in the first and .79 at the second survey). Scores ≥3 on the CES-D 8 indicated depressive symptoms (Steffick, 2000). Exposure variable HGS was measured with the Smedley© Digital Hand Dynamometer (12–0286) (Gómez-Olivé et al., 2018), and weak HGS was defined as “<30 kg for men and <20 kg for women using the mean value of two HG measurements with the dominant hand” (Carvalho et al., 2021; Cruz-Jentoft et al., 2010). Covariates 1. Sociodemographic information included country of birth, age, sex, educational level, and a quintile of asset-based household wealth. 2. Two items on current smokeless tobacco use and current tobacco use assessed current tobacco use (Gómez-Olivé et al., 2018). Using as a cut-off ≥2 affirmative responses on the 4-item CAGE scale defined alcohol dependence (A., 1984), (Cronbach’s alpha was .82). 3. Body Mass Index (BMI) was measured and classified according to WHO criteria (WHO, 2000). 4. Hypertension was measured based on the last two of three blood pressure readings and classified based on National Committee criteria (Chobanian et al., 2003). Humanitas: Indonesian Psychological Journal 25 Peltzer (Hand grip strength and depression among rural older South Africans) 5. Dyslipidemia was defined as: “total cholesterol > 6.21 mmol/L, HDL-C < 1.19 mmol/L, LDL-C > 4.1 mmol/L, triglycerides >2.25 mmol/L,” ever diagnosed or medication use for high cholesterol (Gómez-Olivé et al., 2018). 6. Diabetes was “classified with fasting glucose (defined as > 8 hours) > 7mmol/L (126 mg/dL),” ever diagnosed or medication use for diabetes (Gómez-Olivé et al., 2018). 7. Physical activity and its levels were assessed and classified with the “General Physical Activity Questionnaire (GPAQ)” (Armstrong & Bull, 2006; WHO, 2009). Data Analysis The proportion of persons with the incident and persistent depression was calculated and described. The first longitudinal logistic regression analysis excluded those with depression at baseline, including a sample of 4092 participants, to estimate incident depression, and the second logistic regression analysis estimated longitudinal persistent depression. In the logistic regression model, HGS was the main predictor, controlled for sociodemographics, substance use, physical activity, BMI, and chronic conditions. Inverse probability weights were applied to account for attrition and mortality at follow-up (Kobayashi, Morris, et al., 2021b). p <.05 was accepted as significant. All analyzes were performed with StataSE 15.0 (College Station, TX, USA). Results Participant characteristics by the incident and persistent depression In total, 835 adults out of 3268 participants without depression in Wave 1 (25.0%) had incident depression in Wave 2, and 184 adults out of 3866 participants who had depression in Wave 1 (4.8%) screened positive for depression at both Wave 1 and 2 (persistent depression). The prevalence of weak HGS was 51.5%. Table 1 shows sample characteristics of participants by the incident and persistent depression. Table 1 Sample Characteristics by the Incident and Persistent Depression, Agincourt, South Africa, 2014-2019 Baseline variables Sample Incident depression Persistent depression N (%) N (%) N (%) Age (in years) 40-49 50-59 60-69 70-79 ≥80 884 (17.6) 1358 (27.1) 1274 (25.4) 918 (18.3) 583 (11.6) 159 (24.1) 221 (23.8) 216 (26.2) 134 (25.0) 70 (29.2) 20 (2.7) 47 (3.9) 48 (4.9) 45 (7.0) 22 (7.2) Sex Female Male 2713 (53.6) 2346 (46.4) 457 (25.8) 349 (24.4) 107 (5.0) 77 (4.6) Education None 1-7 years 8-11 12 or more 2307 (49.1) 1613 (32.0) 537 (10.7) 585 (11.6) 360 (26.7) 251 (24.3) 89 (23.2) 102 (23.6) 98 (6.1) 64 (5.0) 12 (2.4) 10 (2.0) Wealth index Low Middle High 2047 (40.5) 991 (19.6) 2021 (39.9) 329 (27.1) 146 (23.1) 331 (24.2) 80 (5.5) 38 (5.0) 66 (4.1) Alcohol dependence No Yes 4988 (98.7) 68 (1.3) 798 (25.2) 8 (18.0) 178 (4.7) 6 (11.5) Current tobacco use No Yes 4264 (84.4) 790 (15.6) 671 (24.3) 135 (29.8) 155 (4.7) 29 (5.2) Body mass index Normal Under Overweight Obesity 1719 (36.7) 258 (5.5) 1328 (28.3) 1384 (29.5) 277 (24.8) 37 (29.9) 206 (23.4) 255 (26.2) 58 (4.5) 14 (9.0) 51 (4.8) 53 (4.5) 26 ISSN 2598-6368 (online) / ISSN 1693-7236 (print) Peltzer (Hand grip strength and depression among rural older South Africans) Table 1 (Continue) Sample Characteristics by the Incident and Persistent Depression, Agincourt, South Africa, 2014-2019 Baseline variables Sample Incident depression Persistent depression N (%) N (%) N (%) Hypertension No Yes 2052 (41.6) 2884 (58.4) 340 (25.4) 450 (24.8) 63 (4.0) 117 (5.4) Diabetes No Yes 4093 (88.0) 559 (12.0) 668 (24.9) 86 (29.4) 143 (4.5) 31 (8.1) Dyslipidaemia No Yes 2389 (56.2) 1862 (43.8) 394 (25.0) 310 (27.0) 84 (4.5) 77 (5.5) Physical activity Low Moderate High 2221 (44.0) 1143 (22.7) 1674 (33.3) 331 (25.5) 202 (24.8) 300 (24.7) 102 (6.0) 34 (3.6) 63 (4.4) Hang grip strength Strong Weak 2043 (50.8) 1973 (49.2) 360 (23.5) 312 (26.5) 69 (4.1) 73 (5.4) Associations between weak HGS and incident depression In the fully adjusted model for individuals with no depressive symptoms at baseline, weak HGS increased the odds of incident depressive symptoms between the two sexes (AOR: 1.24, 95% CI: 1.04-1.47), and among women (AOR: 1.33, 95% CI: 1.05-1.68). No models among men showed a significant effect of weak HGS on incident depressive symptoms (see Table 2). Table 2 Association between Hand Grip Strength and Incident Depressive Symptoms, Agincourt, South Africa, 2014-2019 Variable Unadjusted model Model-1 Model-2 Model-3 COR (95% CI) AOR (95% CI) AOR (95% CI) AOR (95% CI) Box sexes Weak HGS No 1 (Reference) 1 (Reference) 1 (Reference) 1 (Reference) Yes 1.18 (1.04, 1.37)* 1.19 (1.01, 1.39)* 1.19 (1.01, 1.40)* 1.24 (1.04, 1.47)* Male Weak HGS No 1 (Reference) 1 (Reference) 1 (Reference) 1 (Reference) Yes 1.12 (.90, 1.39) 1.11 (.88, 141) 1.13 (.89, 1.44) 1.14 (.88, 1.49) Female Weak HGS No 1 (Reference) 1 (Reference) 1 (Reference) 1 (Reference) Yes 1.26 (1.03, 1.54)* 1.25 (1.01, 1.55)* 1.25 (1.00, 1.55)* 1.33 (1.05, 1.68)* *p <. 05; COR=Crude Odds Ratio; AOR=Adjusted Odds Ratio Model 1: Adjusted for age, sex, education, and wealth status. Model II: Adjusted for Model 1 variables, plus substance use, physical activity, and body mass index. Model III: Adjusted for Model I and II variables, plus dyslipidemia, hypertension, and diabetes. Associations between weak HGS and persistent depression Table 3 shows logistic regression models with people who had depressive symptoms at baseline and follow-up. In an unadjusted analysis between sexes and between men, weak Humanitas: Indonesian Psychological Journal 27 Peltzer (Hand grip strength and depression among rural older South Africans) HGS increased the odds of persistent depressive symptoms. However, in the adjusted analysis, among both sexes, among men and women, no significant associations with persistent depressive symptoms were found (see Table 3). Table 3 Association between Hand Grip Strength and Persistent Depressive Symptoms, Agincourt, South Africa, 2014-2019 Variable Unadjusted model Model-1 Model-2 Model-3 COR (95% CI) AOR (95% CI) AOR (95% CI) AOR (95% CI) Both sexes Weak HGS No 1 (Reference) 1 (Reference) 1 (Reference) 1 (Reference) Yes 1.35 (1.02, 1.78)* 1.07 (.80, 1.45) 1.06 (.77, 1.45) 1.01 (.72, 1.42) Male Weak HGS No 1 (Reference) 1 (Reference) 1 (Reference) 1 (Reference) Yes 1.59 (1.04, 2.42)* 1.21 (.76, 1.91) 1.21 (.75, 1.94) 1.12 (.67, 1.88) Female Weak HGS No 1 (Reference) 1 (Reference) 1 (Reference) 1 (Reference) Yes 1.20 (.83, 1.75) .98 (.66, 1.47) .97 (.63, 1.48) .94 (.59, 1.49) *p < .05; COR=Crude Odds Ratio; AOR=Adjusted Odds Ratio Model 1: Adjusted for age, sex, education, and wealth status. Model II: Adjusted for Model 1 variables, plus substance use, body mass index, and physical activity. Model III: Adjusted for Model I and II variables, plus dyslipidemia, hypertension, and diabetes. Discussion In this first longitudinal study among people 40 years and older in Africa, we found that weak HGS increased the odds of incident depressive symptoms four years later, among both sexes, among women but not among men of ageing adults in South Africa. These results are contrary to a recent review that found low HGS increases the risk of depressive symptoms among males but not females (Huang et al., 2021), but similar to a longitudinal study among older adults in Ireland (McDowell et al., 2018). Possible reasons for these sex differences may be related to the role of estrogen in affecting muscle strength (Collins et al., 2019) and the role of estradiol action in the regulation of gene expression that modulates serotonin neurotransmission implicated in depression (Gu et al., 2021; Hernández-Hernández et al., 2019). Still, further research is warranted on this issue (Gu et al., 2021). In the unadjusted analysis, weak HGS increased the odds of persistent depressive symptoms between the sexes and between men but not women. However, no association was found in adjusted analysis between weak HGS and persistent depressive symptoms, while some other studies showed a positive association between lower HGS and persistent depression (Carvalho et al., 2021). Overall, findings partially confirm that resistance training to enhance muscle strength in ageing adults may be a beneficial adjunct to prevent depressive symptoms (McDowell et al., 2018; Straight et al., 2016). One of the possible mechanisms to explain the inverse association between HGS and depressive symptoms (Gu et al., 2021) may include that HGS reduces the risk of developing depression through enhancing muscle function that reduces inflammation and oxidative free radicals (Lindqvist et al., 2017; Vezzoli et al., 2019). The limitations of the study include that depression was assessed with a screening questionnaire and not with a diagnostic psychiatric evaluation. Furthermore, participants who were negative for depression in wave 1 may have had depression before. 28 ISSN 2598-6368 (online) / ISSN 1693-7236 (print) Peltzer (Hand grip strength and depression among rural older South Africans) Conclusion Weak HGS was independently associated with the incident, but not persistent depressive symptoms between the two sexes and between women but not between men. Results suggest that improving HGS may help in reducing the development of depressive symptoms, in particular among women. Funding “HAALSI (Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa) is sponsored by the National Institute on Aging (grant number 1P01AG041710-01A1) and is conducted by the Harvard Center for Population and Development Studies in partnership with Witwatersrand University. 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