Application of an egocentric social network approach to examine changes in social connections following treatment for anxiety and depression: A novel measurement tool for clinical trials research?

The epidemic of loneliness and social isolation has been recognized as a public health crisis warranting the same prioritization as other public health issues today, such as obesity, substance use disorders, and tobacco use. Social disconnection is particularly prevalent and disabling among individuals with anxiety and depression, yet it is inadequately evaluated and addressed in most clinical psychology treatment research. Studies generally employ global measures of perceived connectedness, loneliness, or relationship satisfaction, limiting understanding about elements of one's social network that may change with treatment. This study examined changes in the degree (number of people nominated) and quality of one's social network from pre-to post-treatment using an egocentric social network approach in 59 adults (mean age = 30.8 years, range = 18 to 54) with clinically elevated anxiety or depression who were randomized to a cognitive and behavioral positive valence treatment versus waitlist. Participants (egos) named people in their lives (alters) with whom they discussed important issues or spent free time. For each alter, participants rated how close they felt, how close they thought the alter felt to them, and how frequently they communicated. Linear regressions, which included treatment group as a predictor, revealed no group differences in changes in network degree, perceived alter feelings of closeness, or communication frequency, despite prior findings from this sample indicating larger increases in perceived global connectedness in the treatment group. Unexpectedly, the control group reported a greater increase in perceived closeness to alters. Post-hoc analyses revealed this was explained by the treatment group identifying more distal social ties (e.g., extended family, colleagues, roommates) as alters following treatment - an outcome positively associated with global improvements in connectedness. This proof-of-concept study suggests egocentric social network surveys may provide unique information on treatment-related changes in social functioning. Suggestions are provided for adaptations to facilitate application of social network surveys to mental health treatment research.

Amplification of Positivity Treatment for Anxiety and Depression: A Randomized Experimental Therapeutics Trial Targeting Social Reward Sensitivity to Enhance Social Connectedness

BACKGROUND

Social disconnection is common and causes significant impairment in anxiety and depressive disorders, and it does not respond sufficiently to available treatments. The positive valence system supports social bond formation and maintenance but is often hyporesponsive in people with anxiety or depression. We conducted an experimental therapeutics trial to test the hypothesis that targeting positive valence processes through cognitive and behavioral strategies would enhance responsivity to social rewards, a core mechanism underlying social connectedness.

METHODS

Sixty-eight adults who endorsed clinically elevated anxiety and/or depression with social impairment were randomized 1:1:1 to 5 (n = 23) or 10 (n = 22) sessions of amplification of positivity (AMP) treatment or waitlist (n = 23). Pre- to posttreatment change in striatal activity (primary outcome) during social reward anticipation was measured using functional magnetic resonance imaging, and reactivity to a social affiliation task (secondary) and self-reported social connectedness (exploratory) were examined. Primary analyses compared AMP (doses combined) versus waitlist. A second aim was to compare the effects of different doses.

RESULTS

AMP engaged the hypothesized treatment target, leading to greater striatal activation during anticipation of social rewards versus waitlist (d = 1.01 [95% CI = 0.42-1.61]; largest striatal volume). AMP yielded larger improvements in positive affect and approach behavior during the affiliation task (but not other outcomes) and social connectedness. Larger striatal and social connectedness increases were observed for 5-session versus 10-session AMP (d range = 0.08-1.03).

CONCLUSIONS

Teaching people with anxiety or depression strategies to increase positive thoughts, behaviors, and emotions enhances activity in brain regions that govern social reward processing and promotes social connectedness. Social reward sensitivity may be a transdiagnostic target for remediating social disconnection.

Political Differences in American Reports of Sexual Harassment and Assault

Political ideology has been linked to beliefs regarding sexual harassment and assault (SH&A). Using data from the January 2018 Stop Street Sexual Harassment online poll (N = 2,009), this study examined associations of political identity and political ideology with self-reported experiences of being the victim of SH&A. SH&A experiences were coded into four mutually exclusive groups: none, non-physically aggressive harassment, physically aggressive harassment, or sexual assault. Sex-stratified logistic regression models assessed associations of interest, adjusting for participant demographics. Among women, more conservative political ideology was negatively associated with reports of sexual assault, odds ratio (OR) = 0.85, 95% confidence interval (CI) = [0.74, 0.98]. Among males, more conservative political ideology was negatively associated with reports of physically aggressive sexual harassment (OR = 0.85, 95% CI = [0.73, 0.98]), and greater Republican affiliation was negatively associated with reports of sexual assault (OR = 0.82, 95% CI = [0.68, 0.99]). Conservative and Republican women and men are thus less likely to report more severe forms of SH&A, which may explain differences in beliefs on these issues. Research is needed to determine if political differences are due to reporting biases or differential vulnerabilities.

Longitudinal social network analysis of avian mycobacteriosis incidence in a large population of zoo birds

The goal of this study was to evaluate longitudinal patterns of avian mycobacteriosis spread through a social network. Specifically, we wanted to determine whether the patterns of connectivity over time can predict future infections, and whether this pattern can distinguish between different sources of infection. The study population included 13,409 individuals nested in a larger population of birds that were closely monitored in zoological facilities for over 22 years (1992-2014). A retrospective cohort study design and social network connectivity were used to estimate the association between exposure to an infected bird, and development of mycobacteriosis. Avian mycobacteriosis was diagnosed from histopathology and network connectivity was defined by enclosure histories over discrete time periods. Single-variable and multivariable longitudinal, mixed effects logistic regression models examined whether exposure to infected birds, both directly- and indirectly-connected, was associated with development of mycobacteriosis at the next time step. Our adjusted model showed an increased odds of developing mycobacteriosis (odds ratio = 2.15; 95 % CI: 1.48-3.12; p < 0.001) for birds that were directly exposed (i.e., housed in the same aviary) to another infected bird, compared to those with no exposure. Exposure to a positive, indirectly-connected bird at a previous time step was independently associated with an increased risk of mycobacteriosis (odds ratio = 1.56; 95 % CI: 1.11-2.19). This association persisted in adjusted models even when the indirect contacts were housed in distinctly different aviaries and never had contact with the subject of interest or its environment. Adjusted, risk-stratified models further characterized the type of exposure that increased the risk of avian mycobacteriosis. Birds that were exposed in small aviaries were more likely to develop mycobacteriosis than those exposed in larger aviaries and those with no exposure. The lesion distribution and species of the contact (same species versus different species) were also significant predictors of disease risk. Some findings were sensitive to model variation of time divisions and initiation time. Our study shows avian mycobacteriosis spread through the social network in quantifiable and discernable patterns. We provide empirical evidence that a contagious process drives some of the observed infection, but we also show low transmissibility based on sustained patterns of low incidence over time even when large groups of birds are exposed. Targeted risk mitigation efforts based on the characteristics of the exposure may be effective at reducing risk of avian mycobacteriosis while enhancing population sustainability.

Stay-at-home orders associate with subsequent decreases in COVID-19 cases and fatalities in the United States

Governments issue “stay-at-home” orders to reduce the spread of contagious diseases, but the magnitude of such orders’ effectiveness remains uncertain. In the United States these orders were not coordinated at the national level during the coronavirus disease 2019 (COVID-19) pandemic, which creates an opportunity to use spatial and temporal variation to measure the policies’ effect. Here, we combine data on the timing of stay-at-home orders with daily confirmed COVID-19 cases and fatalities at the county level during the first seven weeks of the outbreak in the United States. We estimate the association between stay-at-home orders and alterations in COVID-19 cases and fatalities using a difference-in-differences design that accounts for unmeasured local variation in factors like health systems and demographics and for unmeasured temporal variation in factors like national mitigation actions and access to tests. Compared to counties that did not implement stay-at-home orders, the results show that the orders are associated with a 30.2 percent (11.0 to 45.2) average reduction in weekly incident cases after one week, a 40.0 percent (23.4 to 53.0) reduction after two weeks, and a 48.6 percent (31.1 to 61.7) reduction after three weeks. Stay-at-home orders are also associated with a 59.8 percent (18.3 to 80.2) average reduction in weekly fatalities after three weeks. These results suggest that stay-at-home orders might have reduced confirmed cases by 390,000 (170,000 to 680,000) and fatalities by 41,000 (27,000 to 59,000) within the first three weeks in localities that implemented stay-at-home orders.

Social network analysis and whole-genome sequencing to evaluate disease transmission in a large, dynamic population: A study of avian mycobacteriosis in zoo birds

This study combined a social network analysis and whole-genome sequencing (WGS) to test for general patterns of contagious spread of a mycobacterial infection for which pathways of disease acquisition are not well understood. Our population included 275 cases diagnosed with avian mycobacteriosis that were nested in a source population of 16,430 birds at San Diego Zoo Wildlife Alliance facilities from 1992 through mid-2014. Mycobacteria species were determined using conventional methods and whole genome sequencing (WGS). Mycobacterium avium avium (MAA) and Mycobacterium genavense were the most common species of mycobacteria identified and were present in different proportions across bird taxa. A social network for the birds was constructed from the source population to identify directly and indirectly connected cases during time periods relevant to disease transmission. Associations between network connectivity and genetic similarity of mycobacteria (as determined by clusters of genotypes separated by few single nucleotide polymorphisms, or SNPs) were then evaluated in observed and randomly generated network permutations. Findings showed that some genotypes clustered along pathways of bird connectivity, while others were dispersed throughout the network. The proportion of directly connected birds having a similar mycobacterial genotype was 0.36 and significant (p<0.05). This proportion was higher (0.58) and significant for MAA but not for M. genavense. Evaluations of SNP distributions also showed genotypes of MAA were more related in connected birds than expected by chance; however, no significant patterns of genetic relatedness were identified for M. genavense, although data were sparse. Integrating the WGS analysis of mycobacteria with a social network analysis of their host birds revealed significant genetic clustering along pathways of connectivity, namely for MAA. These findings are consistent with a contagious process occurring in some, but not all, case clusters.

Stay-at-home orders associate with subsequent decreases in COVID-19 cases and fatalities in the United States

Governments issue "stay-at-home" orders to reduce the spread of contagious diseases, but the magnitude of such orders' effectiveness remains uncertain. In the United States these orders were not coordinated at the national level during the coronavirus disease 2019 (COVID-19) pandemic, which creates an opportunity to use spatial and temporal variation to measure the policies' effect. Here, we combine data on the timing of stay-at-home orders with daily confirmed COVID-19 cases and fatalities at the county level during the first seven weeks of the outbreak in the United States. We estimate the association between stay-at-home orders and alterations in COVID-19 cases and fatalities using a difference-in-differences design that accounts for unmeasured local variation in factors like health systems and demographics and for unmeasured temporal variation in factors like national mitigation actions and access to tests. Compared to counties that did not implement stay-at-home orders, the results show that the orders are associated with a 30.2 percent (11.0 to 45.2) average reduction in weekly incident cases after one week, a 40.0 percent (23.4 to 53.0) reduction after two weeks, and a 48.6 percent (31.1 to 61.7) reduction after three weeks. Stay-at-home orders are also associated with a 59.8 percent (18.3 to 80.2) average reduction in weekly fatalities after three weeks. These results suggest that stay-at-home orders might have reduced confirmed cases by 390,000 (170,000 to 680,000) and fatalities by 41,000 (27,000 to 59,000) within the first three weeks in localities that implemented stay-at-home orders.

Spatiotemporal network structure among "friends of friends" reveals contagious disease process

Disease transmission can be identified in a social network from the structural patterns of contact. However, it is difficult to separate contagious processes from those driven by homophily, and multiple pathways of transmission or inexact information on the timing of infection can obscure the detection of true transmission events. Here, we analyze the dynamic social network of a large, and near-complete population of 16,430 zoo birds tracked daily over 22 years to test a novel “friends-of-friends” strategy for detecting contagion in a social network. The results show that cases of avian mycobacteriosis were significantly clustered among pairs of birds that had been in direct contact. However, since these clusters might result due to correlated traits or a shared environment, we also analyzed pairs of birds that had never been in direct contact but were indirectly connected in the network via other birds. The disease was also significantly clustered among these friends of friends and a reverse-time placebo test shows that homophily could not be causing the clustering. These results provide empirical evidence that at least some avian mycobacteriosis infections are transmitted between birds, and provide new methods for detecting contagious processes in large-scale global network structures with indirect contacts, even when transmission pathways, timing of cases, or etiologic agents are unknown.

Using social and behavioural science to support COVID-19 pandemic response

The COVID-19 pandemic represents a massive global health crisis. Because the crisis requires large-scale behaviour change and places significant psychological burdens on individuals, insights from the social and behavioural sciences can be used to help align human behaviour with the recommendations of epidemiologists and public health experts. Here we discuss evidence from a selection of research topics relevant to pandemics, including work on navigating threats, social and cultural influences on behaviour, science communication, moral decision-making, leadership, and stress and coping. In each section, we note the nature and quality of prior research, including uncertainty and unsettled issues. We identify several insights for effective response to the COVID-19 pandemic and highlight important gaps researchers should move quickly to fill in the coming weeks and months.

Assortative mating at loci under recent natural selection in humans

Genetic correlation between mates at specific loci can greatly alter the evolutionary trajectory of a species. Genetic assortative mating has been documented in humans, but its existence beyond population stratification (shared ancestry) has been a matter of controversy. Here, we develop a method to measure assortative mating across the genome at 1,044,854 single-nucleotide polymorphisms (SNPs), controlling for population stratification and cohort-specific cryptic relatedness. Using data on 1683 human couples from two data sources, we find evidence for both assortative and disassortative mating at specific, discernible loci throughout the entire genome. Then, using the composite of multiple signals (CMS) score, we also show that the group of SNPs exhibiting the most assortativity has been under stronger recent positive selection. Simulations using realistic inputs confirm that assortative mating might indeed affect changes in allele frequency over time. These results suggest that genetic assortative mating may be speeding up evolution in humans.

The Structure of Negative Social Ties in Rural Village Networks

Negative (antagonistic) connections have been of longstanding theoretical importance for social structure. In a population of 24,696 adults interacting face to face within 176 isolated villages in western Honduras, we measured all connections that were present, amounting to 105,175 positive and 16,448 negative ties. Here, we show that negative and positive ties exhibit many of the same structural characteristics. We then develop a complete taxonomy of all 138 possible triads of two-type relationships. Consistent with balance theory, we find that antagonists of friends and friends of antagonists tend to be antagonists; but, in an important empirical refutation of balance theory, we find that antagonists of antagonists also tend to be antagonists, not friends. Finally, villages with comparable levels of animosity tend to be geographically proximate. Similar processes, involving social contact, give rise to both positive and negative social ties in rural villages, and negative ties play an important role in social structure.

Weather impacts expressed sentiment

We conduct the largest ever investigation into the relationship between meteorological conditions and the sentiment of human expressions. To do this, we employ over three and a half billion social media posts from tens of millions of individuals from both Facebook and Twitter between 2009 and 2016. We find that cold temperatures, hot temperatures, precipitation, narrower daily temperature ranges, humidity, and cloud cover are all associated with worsened expressions of sentiment, even when excluding weather-related posts. We compare the magnitude of our estimates with the effect sizes associated with notable historical events occurring within our data.

Social connectedness is associated with fibrinogen level in a human social network

Socially isolated individuals face elevated rates of illness and death. Conventional measures of social connectedness reflect an individual's perceived network and can be subject to bias and variation in reporting. In this study of a large human social network, we find that greater indegree, a sociocentric measure of friendship and familial ties identified by a subject's social connections rather than by the subject, predicts significantly lower concentrations of fibrinogen (a biomarker of inflammation and cardiac risk), after adjusting for demographics, education, medical history and known predictors of cardiac risk. The association between fibrinogen and social isolation, as measured by low indegree, is comparable to the effect of smoking, and greater than that of low education, a conventional measure of socioeconomic disadvantage. By contrast, outdegree, which reflects an individual's perceived connectedness, displays a significantly weaker association with fibrinogen concentrations.

International chicken trade and increased risk for introducing or reintroducing highly pathogenic avian influenza A (H5N1) to uninfected countries

Every year billions of chickens are shipped thousands of miles around the globe in order to meet the ever increasing demands for this cheap and nutritious protein source. Unfortunately, transporting chickens internationally can also increase the chance for introducing zoonotic viruses, such as highly pathogenic avian influenza A (H5N1) to new countries. Our study used a retrospective analysis of poultry trading data from 2003 through 2011 to assess the risk of H5N1 poultry infection in an importing country. We found that the risk of infection in an importing country increased by a factor of 1.3 (95% CI: 1.1-1.5) for every 10-fold increase in live chickens imported from countries experiencing at least one H5N1 poultry case during that year. These results suggest that the risk in a particular country can be significantly reduced if imports from countries experiencing an outbreak are decreased during the year of infection or if biosecurity measures such as screening, vaccination, and infection control practices are increased. These findings show that limiting trade of live chickens or increasing infection control practices during contagious periods may be an important step in reducing the spread of H5N1 and other emerging avian influenza viruses.

Nighttime temperature and human sleep loss in a changing climate

Human sleep is highly regulated by temperature. Might climate change-through increases in nighttime heat-disrupt sleep in the future? We conduct the inaugural investigation of the relationship between climatic anomalies, reports of insufficient sleep, and projected climate change. Using data from 765,000 U.S. survey respondents from 2002 to 2011, coupled with nighttime temperature data, we show that increases in nighttime temperatures amplify self-reported nights of insufficient sleep. We observe the largest effects during the summer and among both lower-income and elderly respondents. We combine our historical estimates with climate model projections and detail the potential sleep impacts of future climatic changes. Our study represents the largest ever investigation of the relationship between sleep and ambient temperature and provides the first evidence that climate change may disrupt human sleep.

Social influence and political mobilization: Further evidence from a randomized experiment in the 2012 U.S. presidential election

A large-scale experiment during the 2010 U.S. Congressional Election demonstrated a positive effect of an online get-out-the-vote message on real world voting behavior. Here, we report results from a replication of the experiment conducted during the U.S. Presidential Election in 2012. In spite of the fact that get-out-the-vote messages typically yield smaller effects during high-stakes elections due to saturation of mobilization efforts from many sources, a significant increase in voting was again observed. Voting also increased significantly among the close friends of those who received the message to go to the polls, and the total effect on the friends was likely larger than the direct effect, suggesting that understanding social influence effects is potentially even more important than understanding the direct effects of messaging. These results replicate earlier work and they add to growing evidence that online social networks can be instrumental for spreading offline behaviors.

Exploiting social influence to magnify population-level behaviour change in maternal and child health: study protocol for a randomised controlled trial of network targeting algorithms in rural Honduras

INTRODUCTION

Despite global progress on many measures of child health, rates of neonatal mortality remain high in the developing world. Evidence suggests that substantial improvements can be achieved with simple, low-cost interventions within family and community settings, particularly those designed to change knowledge and behaviour at the community level. Using social network analysis to identify structurally influential community members and then targeting them for intervention shows promise for the implementation of sustainable community-wide behaviour change.

METHODS AND ANALYSIS

We will use a detailed understanding of social network structure and function to identify novel ways of targeting influential individuals to foster cascades of behavioural change at a population level. Our work will involve experimental and observational analyses. We will map face-to-face social networks of 30 000 people in 176 villages in Western Honduras, and then conduct a randomised controlled trial of a friendship-based network-targeting algorithm with a set of well-established care interventions. We will also test whether the proportion of the population targeted affects the degree to which the intervention spreads throughout the network. We will test scalable methods of network targeting that would not, in the future, require the actual mapping of social networks but would still offer the prospect of rapidly identifying influential targets for public health interventions.

ETHICS AND DISSEMINATION

The Yale IRB and the Honduran Ministry of Health approved all data collection procedures (Protocol number 1506016012) and all participants will provide informed consent before enrolment. We will publish our findings in peer-reviewed journals as well as engage non-governmental organisations and other actors through venues for exchanging practical methods for behavioural health interventions, such as global health conferences. We will also develop a 'toolkit' for practitioners to use in network-based intervention efforts, including public release of our network mapping software.

TRIAL REGISTRATION NUMBER

NCT02694679; Pre-results.

Dueling biological and social contagions

Numerous models explore how a wide variety of biological and social phenomena spread in social networks. However, these models implicitly assume that the spread of one phenomenon is not affected by the spread of another. Here, we develop a model of “dueling contagions”, with a particular illustration of a situation where one is biological (influenza) and the other is social (flu vaccination). We apply the model to unique time series data collected during the 2009 H1N1 epidemic that includes information about vaccination, flu, and face-to-face social networks. The results show that well-connected individuals are more likely to get vaccinated, as are people who are exposed to friends who get vaccinated or are exposed to friends who get the flu. Our dueling contagion model suggests that other epidemiological models may be dramatically underestimating the R₀ of contagions. It also suggests that the rate of vaccination contagion may be even more important than the biological contagion in determining the course of the disease. These results suggest that real world and online platforms that make it easier to see when friends have been vaccinated (personalized vaccination campaigns) and when they get the flu (personalized flu warnings) could have a large impact on reducing the severity of epidemics. They also suggest possible benefits from understanding the coevolution of many kinds of dueling contagions.

Face-to-Face and Online Networks: College Students' Experiences in a Weight-Loss Trial

This study aimed to understand how college students participating in a 2-year randomized controlled trial (Project SMART: Social and Mobile Approach to Reduce Weight; N = 404) engaged their social networks and used social and mobile technologies to try and lose weight. Participants in the present study (n = 20 treatment, n = 18 control) were approached after a measurement visit and administered semi-structured interviews. Interviews were analyzed using principles from grounded theory. Treatment group participants appreciated the timely support provided by the study and the integration of content across multiple technologies. Participants in both groups reported using non-study-designed apps to help them lose weight, and many participants knew one another outside of the study. Individuals talked about weight-loss goals with their friends face to face and felt accountable to follow through with their intentions. Although seeing others' success online motivated many, there was a range of perceived acceptability in talking about personal health-related information on social media. The findings from this qualitative study can inform intervention trials using social and mobile technologies to promote weight loss. For example, weight-loss trials should measure participants' use of direct-to-consumer technologies and interconnectivity so that treatment effects can be isolated and cross-contamination accounted for.

An exploratory comparison of name generator content: Data from rural India

Since the 1970s sociologists have explored the best means for measuring social networks, although few name generator analyses have used sociocentric data or data from developing countries, partly because sociocentric studies in developing countries have been scant. Here, we analyze 12 different name generators used in a sociocentric network study conducted in 75 villages in rural Karnataka, India. Having unusual sociocentric data from a non-Western context allowed us to extend previous name generator research through the unique analyses of network structural measures, an extensive consideration of homophily, and investigation of status difference between egos and alters. We found that domestic interaction questions generated networks that were highly clustered and highly centralized. Similarity between respondents and their nominated contacts was strongest for gender, caste, and religion. We also found that domestic interaction name generators yielded the most homogeneous ties, while advice questions yielded the most heterogeneous. Participants were generally more likely to nominate those of higher social status, although certain questions, such as who participants talk to uncovered more egalitarian relationships, while other name generators elicited the names of social contacts distinctly higher or lower in status than the respondent. Some questions also seemed to uncover networks that were specific to the cultural context, suggesting that network researchers should balance local relevance with global generalizability when choosing name generators.

Formation of raiding parties for intergroup violence is mediated by social network structure

Intergroup violence is common among humans worldwide. To assess how within-group social dynamics contribute to risky, between-group conflict, we conducted a 3-y longitudinal study of the formation of raiding parties among the Nyangatom, a group of East African nomadic pastoralists currently engaged in small-scale warfare. We also mapped the social network structure of potential male raiders. Here, we show that the initiation of raids depends on the presence of specific leaders who tend to participate in many raids, to have more friends, and to occupy more central positions in the network. However, despite the different structural position of raid leaders, raid participants are recruited from the whole population, not just from the direct friends of leaders. An individual's decision to participate in a raid is strongly associated with the individual's social network position in relation to other participants. Moreover, nonleaders have a larger total impact on raid participation than leaders, despite leaders' greater connectivity. Thus, we find that leaders matter more for raid initiation than participant mobilization. Social networks may play a role in supporting risky collective action, amplify the emergence of raiding parties, and hence facilitate intergroup violence in small-scale societies.

Using social and mobile tools for weight loss in overweight and obese young adults (Project SMART): a 2 year, parallel-group, randomised, controlled trial

BACKGROUND

Few weight loss interventions are evaluated for longer than a year, and even fewer employ social and mobile technologies commonly used among young adults. We assessed the efficacy of a 2 year, theory-based, weight loss intervention that was remotely and adaptively delivered via integrated user experiences with Facebook, mobile apps, text messaging, emails, a website, and technology-mediated communication with a health coach (the SMART intervention).

METHODS

In this parallel-group, randomised, controlled trial, we enrolled overweight or obese college students (aged 18-35 years) from three universities in San Diego, CA, USA. Participants were randomly assigned (1:1) to receive either the intervention (SMART intervention group) or general information about health and wellness (control group). We used computer-based permuted-block randomisation with block sizes of four, stratified by sex, ethnicity, and college. Participants, study staff, and investigators were masked until the intervention was assigned. The primary outcome was objectively measured weight in kg at 24 months. Differences between groups were evaluated using linear mixed-effects regression within an intention-to-treat framework. Objectively measured weight at 6, 12, and 18 months was included as a secondary outcome. The trial is registered with ClinicalTrials.gov, number NCT01200459.

FINDINGS

Between May 18, 2011, and May 17, 2012, 404 individuals were randomly assigned to the intervention (n=202) or control (n=202). Participants' mean (SD) age was 22·7 (3·8) years. 284 (70%) participants were female and 125 (31%) were Hispanic. Mean (SD) body-mass index at baseline was 29·0 (2·8) kg/m(2). At 24 months, weight was assessed in 341 (84%) participants, but all 404 were included in analyses. Weight, adjusted for sex, ethnicity, and college, was not significantly different between the groups at 24 months (-0·79 kg [95% CI -2·02 to 0·43], p=0·204). However, weight was significantly less in the intervention group compared with the control group at 6 months (-1·33 kg [95% CI -2·36 to -0·30], p=0·011) and 12 months (-1·33 kg [-2·30 to -0·35], p=0·008), but not 18 months (-0·67 kg [95% CI -1·69 to 0·35], p=0·200). One serious adverse event in the intervention group (gallstones) could be attributable to rapid and excessive weight loss.

INTERPRETATION

Social and mobile technologies did not facilitate sustained reductions in weight among young adults, although these approaches might facilitate limited short-term weight loss.

FUNDING

The National Heart, Lung, and Blood Institute of the National Institutes of Health (U01 HL096715).

Intimate partner violence norms cluster within households: an observational social network study in rural Honduras

Background

Intimate partner violence (IPV) is a complex global problem, not only because it is a human rights issue, but also because it is associated with chronic mental and physical illnesses as well as acute health outcomes related to injuries for women and their children. Attitudes, beliefs, and norms regarding IPV are significantly associated with the likelihood of both IPV experience and perpetration.

Methods

We investigated whether IPV acceptance is correlated across socially connected individuals, whether these correlations differ across types of relationships, and whether social position is associated with the likelihood of accepting IPV. We used sociocentric network data from 831 individuals in rural Honduras to assess the association of IPV acceptance between socially connected individuals across 15 different types of relationships, both within and between households. We also investigated the association between network position and IPV acceptance.

Results

We found that having a social contact that accepts IPV is strongly associated with IPV acceptance among individuals. For women the clustering of IPV acceptance was not significant in between-household relationships, but was concentrated within households. For men, however, while IPV acceptance was strongly clustered within households, men’s acceptance of IPV was also correlated with people with whom they regularly converse, their mothers and their siblings, regardless of household. We also found that IPV was more likely to be accepted by less socially-central individuals, and that the correlation between a social contact’s IPV acceptance was stronger on the periphery, suggesting that, as a norm, it is held on the periphery of the community.

Conclusion

Our results show that differential targeting of individuals and relationships in order to reduce the acceptability and, subsequently, the prevalence of IPV may be most effective. Because IPV norms seem to be strongly held within households, the household is probably the most logical unit to target in order to implement change. This approach would include the possible benefit of a generational effect. Finally, in social contexts in which perpetration of IPV is not socially acceptable, the most effective strategy may be to implement change not at the center but at the periphery of the community.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-2893-4) contains supplementary material, which is available to authorized users.

Self-comparisons as motivators for healthy behavior

OBJECTIVE

We explored whether individuals' comparison of themselves to their social contacts, specifically feeling fitter or thinner than friends, is a significant predictor of three weight-loss behaviors (dieting, reducing alcohol, exercising).

METHODS

We used a longitudinal survey of a national sample of Americans (N = 20,373) to measure respondents' personal social networks and their self-comparisons to their social contacts at two annual waves.

RESULTS

Participants who felt thinner than friends in Wave 1 had 1.16 lower odds of dieting in Wave 2. Those who felt fitter than friends in Wave 1 had 1.10 times higher odds of reducing alcohol and 1.18 times higher odds of exercising in Wave 2. We found that 20% of the relationship between feeling thin at baseline and subsequent dieting may be because feeling heavier than friends makes one want to lose weight. This same dynamic accounts for 25% of the relationship between feeling fit and dieting and 12% of the relationship between feeling thin and reducing alcohol.

CONCLUSIONS

These results suggest that normative self-comparison with important others is a potentially salient determinant of obesity-related health behavior and appears to work differently depending upon the behavior. Interventions may benefit from exploiting social comparisons in targeted ways.