Subjective social position and cognitive function in a longitudinal cohort of older, rural South African adults, 2014-2019

Higher subjective socioeconomic status is linked to increased charitable giving and mentalizing-related neural value coding

Socioeconomic status (SES), a concept related to an individual's economic and social position relative to others, can shape social interactions like altruistic behaviors. However, little is known about the exact neurocognitive mechanisms that link SES with altruism. Our study aimed to provide a comprehensive account of the sociocognitive and neural mechanisms through which SES affects charitable giving - an important variant of human altruism. To this end, participants completed a charitable donation task while their brain activity was measured using functional magnetic resonance imaging (fMRI). We also assessed participants' socio-cognitive ability to infer other people's mental states (i.e., mentalizing) - a driver of prosocial behavior - in an independent social task. Behaviorally, we found that both charitable giving and social cognition were status-dependent, as subjective SES positively predicted donations and mentalizing capacity. Moreover, the link between SES and charitable giving was mediated by individuals' mentalizing capacity. At the neural level, a multivariate pattern analysis of fMRI data revealed that higher subjective SES was associated with stronger value coding in the right temporoparietal junction (rTPJ). The strength of this value representation predicted charitable giving and was linked to mentalizing. Furthermore, we observed an increased negative functional coupling between rTPJ and left putamen with higher SES. Together, increased charitable giving in higher-status individuals could be explained by status-dependent recruitment of mentalizing-related value coding and altered functional connectivity in the brain. Our findings provide insights into the socio- and neurocognitive mechanisms explaining why and when higher SES leads to prosociality, which might ultimately inform targeted interventions to promote prosocial behavior in human societies.

Health risk behaviour and persistent and incident depression among middle-aged and older adults in South Africa

The aim of this study was to assess the association between five health risk behaviours and persistent and incident depressive symptoms in a longitudinal study in South Africa. The sample included 5059 men and women (≥40 years) in 2014/2015, and 4176 in 2018/2019 of the 'Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa'. Depressive symptoms were assessed with the Centre for Epidemiologic Studies Depression scale. Multivariable logistic regression analysis was conducted to assess the associations between five health risk behaviours and persistent and incident depressive symptoms. Results indicate that 5.0% of participants had depressive symptoms at both wave 1 and 2 (persistent depressive symptoms), and 27.9% had incident depressive symptoms in wave 2. Higher education and moderate baseline physical activity were negatively associated and those with cardiovascular disease were positively associated with persistent depressive symptoms. Middle wealth index was negative, and being HIV positive and baseline tobacco use were positively associated with incident depressive symptoms. In conclusion, of five health risk behaviours assessed (inadequate fruit/vegetable intake, alcohol dependence, tobacco use, physical activity, and sedentary behaviour), only moderate physical activity was protective against persistent depressive symptoms, and tobacco use was associated with incident depressive symptoms.

Lifestyle factors, mental health, and incident and persistent intrusive pain among ageing adults in South Africa

OBJECTIVES

The purpose of this study was to evaluate longitudinal associations with incident and persistent intrusive pain among rural South Africans.

METHODS

Longitudinal data from two consecutive waves in 2014/2015 and 2018/2019 in Agincourt, South Africa, were analysed. Pain was assessed with the Brief Pain Inventory.

RESULTS

In all, 683 adults of 3,628 participants without intrusive pain in Wave 1 (19.1%) had incident intrusive pain in Wave 2, 94 adults of 254 participants who had intrusive pain in Wave 1 (38.3%) had intrusive pain at both Wave 1 and 2 (persistent intrusive pain). Furthermore, 358 (7.2%) participants had intrusive pain at baseline. In the fully adjusted model for people without intrusive pain at baseline, the study found that obesity (AOR: 1.31, 95% CI: 1.05-1.63), depressive symptoms (AOR: 1.67, 95% CI: 1.34-2.08), PTSD (AOR: 1.71, 95% CI: 1.19-2.45), and poor sleep quality (AOR: 1.30, 95% CI: 1.04-1.62) were positively associated with incident intrusive pain. Older age was positively, and male sex and daily alcohol use were negatively associated with incident intrusive pain. Furthermore, in the final adjusted logistic regression model, this study found that older age was positively, and underweight, overweight, and high sedentary behavior were negatively associated with persistent intrusive pain.

CONCLUSIONS

Several modifiable risk factors for incident and/or persistent intrusive pain were identified.

Longitudinal correlates of fruit and vegetable consumption with depressive symptoms among middle-aged and older adults in South Africa

BACKGROUND

Fruit and vegetable intake may influence mental well-being. The aim of this study was to assess longitudinal associations between fruit and vegetable intake and depressive symptoms among rural South Africans.

METHODS

This longitudinal community study enrolled 3,891 adults (≥ 40 years) from the "Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa (HAALSI)". Fruit and vegetable intake was assessed by self-report at wave 1, and depressive symptoms were assessed using the Center for Epidemiological Studies Depression Scale at wave 1 and 2. Outcomes were incident and persistent depressive symptoms at wave 2. Logistic regression was used to assess the associations between fruit and vegetable intake at wave 1 and incident, and persistent depressive symptoms.

RESULTS

Results indicate that in the fully adjusted model for individuals with no depressive symptoms at baseline, we found no significant association between frequency of fruit or vegetables intake and incident depressive symptoms. We also found no significant association between frequency of fruit or vegetable intake and persistent depressive symptoms.

CONCLUSION

Fruit and vegetable intake was not significantly associated with incident and persistent depressive symptoms.

Sleep duration and incident and persistent depressive symptoms among a rural ageing population in South Africa

BACKGROUND

The aim of the study was to assess the relationship between sleep duration and incident depressive symptoms (IDS) and persistent depressive symptoms (PDS) using longitudinal data from South Africa.

METHODS

This longitudinal community study enrolled 3891 adults (≥40 years) from the "Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa (HAALSI)". Sleep duration was assessed by self-report at wave 1, and depressive symptoms were assessed using the Center for Epidemiological Studies Depression Scale at wave 1 and 2. Outcomes were incident and persistent depressive symptoms at wave 2. Multivariable logistic regression analysis was conducted to assess the associations between sleep duration at wave 1 and incident, and persistent depressive symptoms.

RESULTS

The prevalence of IDS was 25.6% and PDS 30.8%. The prevalence of very short, short, normal, and long sleep duration at baseline was 3.6%, 10.1%, 60.9% and 25.4%, respectively. In the fully adjusted model, long sleep duration was positively associated with IDS among men (AOR: 1.37, 95% CI: 1.02-1.84), but not among women (AOR: 0.91, 95% CI: 0.67-1.23). No models among both men and women showed a significant association between short sleep and IDS. Long sleep duration was associated with PDS (AOR: 2.04, 95% CI: 1.20-3.48) among men but not among women (AOR: 1.26, 95% CI: 0.76-2.11). Short sleep showed among both sexes no significant associations with PDS.

CONCLUSION

Long but not short sleep duration was independently associated with IDS and PDS among men but not among women.

The relationship between duration of subjective poverty and health among Chinese adults: Evidence from the China Family Panel Study

Introduction

The disadvantaged socioeconomic status could have accumulated negative effects on individual. In the Chinese context, studying subjective and relative poverty is more important under the implementation of the Targeted Poverty Alleviation campaign. This study aims to provide evidence of the relationship between the duration of subjective poverty and both physical and mental health among Chinese adults, using nationally longitudinal data from 2010 to 2018.

Materials and methods

Data were extracted from a nationally representative survey database-the China Family Panel Study (CFPS). The total sample size contains 12,003 adults, with 3,532 in the urban area and 8,471 in the rural area. Self-rated health and depressive symptoms were set as indicators of physical health and mental health, respectively. The duration of subjective poverty was measured by self-rated income level in the local area from 2010 to 2016. A series of ordinary least square regression was adopted to measure the relationship between duration of subjective poverty and health.

Results

For the urban residents, the average duration of subjective poverty is 1.99 time points, while 1.98 time points for the rural residents. Net of objective poverty, duration of subjective poverty has a significantly negative association with individual's self-rated health in the rural sample (Coef. = -0.10, p < 0.001). Compared with those who have not experienced subjective poverty, the self-rated health score of people who experienced four time points is likely to decrease by 0.54 in the rural area and 0.30 in the urban area. In terms of mental health, 1 unit increase in the duration of subjective poverty is related to 0.15 unit increase in Center for Epidemiologic Studies Depression Scale-8 (CES-D8) scores in the urban sample and 0.46 in the rural sample. Compared with those who have not experienced subjective poverty, the CES-D8 scores of people who experienced four time points are likely to increase by 1.47 in the rural area and 0.95 in the urban area.

Conclusion

A longer duration of subjective poverty has a cumulatively negative effect on Chinese residents' physical and mental health, especially in rural area. Our study advocates researchers and policymakers pay more attention to the cumulative effect of subjective poverty on health.

Fruit and vegetable intake and incident and persistent poor sleep quality in a rural ageing population in South Africa: longitudinal study

BACKGROUND

Fruit and vegetable intake may improve sleep.

AIMS

To assess the relationship between fruit and vegetable intake and sleep quality in a longitudinal study.

METHOD

We analysed longitudinal data from two consecutive population surveys of adults in Agincourt, South Africa (2014-2015 and 2018-2019).

RESULTS

In total, 331 of 2975 participants without poor sleep quality in Wave 1 (11.1%) had incident poor sleep quality in Wave 2, and 270 of 3546 participants who had poor sleep quality in Wave 1 (7.6%) had poor sleep quality in both Waves 1 and 2 (persistent poor sleep quality). The prevalence of poor sleep quality at baseline was 17.2%. In the fully adjusted model for people without poor sleep quality at baseline, higher fruit and vegetable consumption (≥5 servings/day) was positively associated with incident poor sleep quality among men (AOR = 1.43, 95% CI 1.51-2.01) but not among women (AOR = 1.09, 95% CI 0.78-1.46). Two or more servings of fruits were positively associated with incident poor sleep quality among men (AOR = 3.35, 95% CI 1.96-5.72) and among women (AOR = 1.84, 95% CI 1.15-2.94). No models among men and women showed a significant association between vegetable intake and incident poor sleep quality or between fruit and vegetable intake, vegetable intake and persistent poor sleep quality. Fruit intake (one serving) was positively associated with persistent poor sleep quality among men (AOR = 1.76, 95% CI 1.00-3.08) but not among women (AOR = 1.42, 95% CI 0.93-2.18).

CONCLUSIONS

Higher fruit and vegetable intake was independently associated with poorer sleep quality among men but not women, and higher fruit but not vegetable intake was associated with poorer sleep quality among both men and women.