Effects of natural hazards on early childhood development: a systematic review protocol

INTRODUCTION

Natural hazards are damaging environmental events, such as fires, droughts and floods, which have negative impacts on human lives, livelihoods and health. Natural hazards are increasing in intensity and severity, and may potentially have harmful effects on the health and development of children who experience them. There are few syntheses of the evidence about the effects of natural hazards on the early development of children aged from birth to 5 years old. The aim of this systematic review and meta-analysis is to determine the impact of natural hazards on the cognitive, motor, language, social and emotional development of children from birth to 5 years old.

METHODS AND ANALYSIS

Comprehensive searches will be conducted in five bibliographic databases: Ovid MEDLINE, Ovid PsycInfo, CINAHL Plus, Scopus and Ovid EMBASE, using predefined search terms to identify the relevant studies. The review will follow the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies will be included if they report on the association between exposure to natural hazards and at least one indicator of early childhood development (ECD). Extracted data will include: main study findings, characteristics of the study design, measures of natural hazards and ECD indicators. Observational studies with cross-sectional, case-control, prospective or retrospective cohort designs will be included in this review. Case descriptions and qualitative studies will be excluded. Study quality will be assessed using the Joanna Brigg's Institute critical appraisal tools. We will conduct a meta-analysis if the reviewed studies are sufficiently homogeneous according to research design, exposure, participants and outcome measures. The meta-analysis will include subgroup analyses (eg, length of exposure to natural hazard, type of natural hazard, ECD indicator).

ETHICS AND DISSEMINATION

The findings will be disseminated through a peer-review publication, policy brief, technical report and report published on institutional stakeholder websites.

PROSPERO REGISTRATION NUMBER

CRD42022331621.

Understanding the relationship between social support and mental health of humanitarian migrants resettled in Australia

Background

Forced migration can lead to loss of social support and increased vulnerability to psychological distress of displaced individuals. The aims were to ascertain the associations of sociodemographic characteristics and social support received by resettled adult humanitarian migrants in Australia; determine the relationship between social support and mental health at different intervals following humanitarian migration; and examine the modification effects of gender, age and migration pathway on that relationship.

Methods

A secondary analysis was conducted of data generated in Waves One (three to six months after resettlement), Three (three years after resettlement) and Five (five years after resettlement) of the Building a New Life in Australia prospective cohort study. The association between sociodemographic characteristics and mental health were examined at each timepoint using a multivariate regression model. Exploratory factor analysis was used to develop a two-factor social support scale (emotional/instrumental and informational support) from a larger set of items collected in the BNLA. Psychological distress was measured by the Kessler-6 scale. Path analysis was used to analyse the relationships between social support and psychological distress among the three time points considering socio-demographic characteristics simultaneously.

Results

A total of 2264 participants were included in the analyses. Age, gender, birth region, migration pathway, education level and English proficiency were significantly associated with both social support types. Main source of income was only significantly associated with informational support. Remoteness area was only significantly associated with emotional/instrumental support. As emotional/instrumental support increased by one standard deviation (SD) at Wave One, psychological distress at Wave Three decreased by 0.34 score [95% CI (− 0.61; − 0.08)]. As informational support at Wave Three increased by one SD, psychological distress at Wave Five decreased by 0.35 score [95% CI (− 0.69; − 0.01)]. The relationships between social support and psychological distress varied between genders, age groups and migration pathways.

Conclusion

Findings demonstrate the importance of emotional/instrumental support and informational support for the medium and long-term mental health of humanitarian migrants. This study also highlights the important of extending current social support provisions and tailoring programs to enhance support received by humanitarian migrant subgroups years after resettlement to improve mental health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-14082-z.

Continuing breastfeeding for at least two years after birth in rural Vietnam: prevalence and psychosocial characteristics

Background

The World Health Organization recommends breastfeeding for at least two years (24 months or more) after birth. In Vietnam, 22% of women continue breastfeeding for at least two years. The aim of this study was to determine the sociodemographic and psychosocial characteristics of mother-baby dyads associated with breastfeeding for 24 months or more in a rural setting in Vietnam.

Methods

A secondary analysis was conducted on existing data obtained from a prospective study in Ha Nam, Vietnam. Women were recruited when they were pregnant and were followed up until 36 months after giving birth. The data were collected between 2009 and 2011. The associations between sociodemographic and psychosocial characteristics and continued breastfeeding for 24 months or more were examined using a multivariable logistic regression model.

Results

Overall, 363 women provided complete data which were included in the analyses. Among those, 20.9% breastfed for 24 months or more. Women who were 31 years old or older were more likely to breastfeed for 24 months or more than women who were 20 years old or younger (adjusted odds ratio, AOR, 9.54 [95% CI 2.25, 40.47]). Women who gave birth to girls were less likely to breastfeed for 24 or more months than women who had boys (AOR 0.44; 95% CI 0.25, 0.80).

Conclusions

This study provides evidence that may be useful for policy-makers to help improve breastfeeding practices for all children in Vietnam by targeting policy towards younger women and women with girls to promote continued breastfeeding for at least 24 months.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13006-021-00427-8.

Plasma levels of trimethylamine-N-oxide can be increased with 'healthy' and 'unhealthy' diets and do not correlate with the extent of atherosclerosis but with plaque instability

AIMS

The microbiome-derived metabolite trimethylamine-N-oxide (TMAO) has attracted major interest and controversy both as a diagnostic biomarker and therapeutic target in atherothrombosis.

METHODS AND RESULTS

Plasma TMAO increased in mice on 'unhealthy' high-choline diets and notably also on 'healthy' high-fibre diets. Interestingly, TMAO was found to be generated by direct oxidation in the gut in addition to oxidation by hepatic flavin-monooxygenases. Unexpectedly, two well-accepted mouse models of atherosclerosis, ApoE-/- and Ldlr-/- mice, which reflect the development of stable atherosclerosis, showed no association of TMAO with the extent of atherosclerosis. This finding was validated in the Framingham Heart Study showing no correlation between plasma TMAO and coronary artery calcium score or carotid intima-media thickness (IMT), as measures of atherosclerosis in human subjects. However, in the tandem-stenosis mouse model, which reflects plaque instability as typically seen in patients, TMAO levels correlated with several characteristics of plaque instability, such as markers of inflammation, platelet activation, and intraplaque haemorrhage.

CONCLUSIONS

Dietary-induced changes in the microbiome, of both 'healthy' and 'unhealthy' diets, can cause an increase in the plasma level of TMAO. The gut itself is a site of significant oxidative production of TMAO. Most importantly, our findings reconcile contradictory data on TMAO. There was no direct association of plasma TMAO and the extent of atherosclerosis, both in mice and humans. However, using a mouse model of plaque instability we demonstrated an association of TMAO plasma levels with atherosclerotic plaque instability. The latter confirms TMAO as being a marker of cardiovascular risk.

Variable contributions of rods and cones to saccadic eye-movement latency in a non-foveating task

Latencies were measured for anti saccades away from a small lit cue that steps +/- 10 deg in complete darkness. Cue luminance and wavelength were varied. Additional measurements were made during dark-adaptation or on backgrounds or at different retinal eccentricities. Luminance matched cues and Palmer's equivalent luminance transformation were also used. Latencies for pure rod and pure cone inputs obey Piéron's law in much the same manner as foveating saccades, except that latencies are somewhat longer. However, as judged by saccadic latency, interaction between rods and cones is quite variable in the anti task. The rod-cone transition either occurs at cue luminances well above the cone threshold and is from pure rod input to primarily cone, or occurs at the cone threshold and is from rods to rods-plus-cones. Direction errors, or reflex foveating saccades, are particularly increased for mesopic cues. The variable behaviour of subjects at the anti task is discussed in relation to temporal multiplexing of rod and cone signals from dark-adapted retinal ganglion cells, the delaying nature of the task, and attentional mechanisms.

Dependence of saccadic eye-movements on stimulus luminance, and an effect of task

Various aspects of saccadic eye-movements are related to stimulus luminance for a small lit stimulus that steps 10 degrees horizontally in complete darkness. The relations depend on whether the stimulus is the target for a foveating saccade, or is the cue for an "anti" saccade which peripheralizes the retinal image of the cue: (1) at scotopic luminances the differences between foveating and anti saccades are diminished, largely because foveation is the more severely affected. Latencies are long amplitudes are scattered, and direction errors are not infrequent in both tasks; (2) the latency-luminance relation for foveating saccades shows an abrupt discontinuity at the perceptual rod-cone transition. Above the cone threshold corrective secondary saccades appear in greater numbers; (3) the corresponding latency transition for anti saccades is anomalous and protracted. Latency remains constant for mesopic cue luminances up to 1.0 log unit brighter than the perceptual rod-cone threshold. Direction errors are especially common in this mesopic luminance range. Mechanisms are discussed.

Rod-cone dependence of saccadic eye-movement latency in a foveating task

This study examines the relations between some well known oculomotor functions (saccades) and well known retinal physiology (dark adaptation): it deals with the overall latency versus target luminance functions, with the underlying rod and cone latency-luminance functions, and with the synergistic interaction between these latency functions for mesopic targets. Saccadic latency was measured to small lit targets presented at 10 deg retinal eccentricity in complete darkness. Target luminance and wavelength were varied. Additional measurements were made during dark adaptation or on backgrounds, or at different retinal eccentricities. Luminance matched stimuli and Palmer's (1968) equivalent luminance transformation were also used. Latency is determined by an achromatic luminance mechanism that receives substantial rod inputs above the cone threshold. Latencies for pure rod or pure cone inputs increase rapidly as target luminance decreases. For the rods this latency increase appears to represent the waiting time for the 140 or so photons (lambda = 507 nm) that are required for a saccade. Errors in direction occur at scotopic luminances, or at low photopic luminances when only cones are functioning.