Christakis, Nicholas A.

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Christakis, Nicholas A.

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Christakis

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Nicholas A.

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Christakis, Nicholas A.

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The Promises and Pitfalls of Genoeconomics
(Annual Reviews, 2012) Benjamin, Daniel J.; Cesarini, David; Chabris, Christopher F.; Glaeser, Edward; Laibson, David; Guðnason, Vilmundur; Harris, Tamara B.; Launer, Lenore J.; Purcell, Shaun M.; Smith, Albert Vernon; Johannesson, Magnus; Magnusson, Patrik K.E.; Christakis, Nicholas A.; Atwood, Craig S.; Hebert, Benjamin; Freese, Jeremy; Hauser, Robert M.; Hauser, Taissa S.; Hultman, Christina M.; Lichtenstein, Paul; Beauchamp, Jonathan P.; Grankvist, Alexander
This article reviews existing research at the intersection of genetics and economics, presents some new findings that illustrate the state of genoeconomics research, and surveys the prospects of this emerging field. Twin studies suggest that economic outcomes and preferences, once corrected for measurement error, appear to be about as heritable as many medical conditions and personality traits. Consistent with this pattern, we present new evidence on the heritability of permanent income and wealth. Turning to genetic association studies, we survey the main ways that the direct measurement of genetic variation across individuals is likely to contribute to economics, and we outline the challenges that have slowed progress in making these contributions. The most urgent problem facing researchers in this field is that most existing efforts to find associations between genetic variation and economic behavior are based on samples that are too small to ensure adequate statistical power. This has led to many false positives in the literature. We suggest a number of possible strategies to improve and remedy this problem: (a) pooling data sets, (b) using statistical techniques that exploit the greater information content of many genes jointly, and (c) focusing on economically relevant traits that are most proximate to known biological mechanisms.
Intermediate Levels of Network Fluidity Amplify Economic Growth and Mitigate Economic Inequality in Experimental Social Networks
(Society for Sociological Science, 2015) Nishi, Akihiro; Shirado, Hirokazu; Christakis, Nicholas A.
Social connections are mutable. Prior experimental work has shown that circumstances fostering an intermediate rate of forming and breaking social ties (“network fluidity”) facilitate the maintenance of optimal levels of cooperation in experimental social networks. Previous observational work has also suggested a relationship between economic outcomes and network structure (measured statically) at a geographic level. However, it is not known how network fluidity might affect economic growth and inequality, particularly in an experimental setting. Using data from a series of online experiments involving a public goods game in 90 independent, dynamic social networks (with N=1,529 subjects), we show that increasing network fluidity simultaneously achieves the highest level of economic growth and the lowest level of economic inequality, up to a point. These effects of network fluidity on economic outcomes are mediated, in these experiments, by the levels of cooperation and tie formation that subjects evince. Finally, we show that wealthier networks are less unequal. Social network fluidity may play an important role in economic outcomes and hence in social welfare.
Variation in Patient-Sharing Networks of Physicians Across the United States
(American Medical Association (AMA), 2012) Landon, Bruce; Keating, Nancy; Barnett, Michael; Onnela, Jukka-Pekka; Paul, Sudeshna; O’Malley, A. James; Keegan, Thomas; Christakis, Nicholas A.
Using Friends as Sensors to Detect Global-Scale Contagious Outbreaks
(Public Library of Science (PLoS), 2014) Garcia-Herranz, Manuel; Moro, Esteban; Cebrian, Manuel; Christakis, Nicholas A.; Fowler, James H.
Recent research has focused on the monitoring of global–scale online data for improved detection of epidemics, mood patterns, movements in the stock market political revolutions, box-office revenues, consumer behaviour and many other important phenomena. However, privacy considerations and the sheer scale of data available online are quickly making global monitoring infeasible, and existing methods do not take full advantage of local network structure to identify key nodes for monitoring. Here, we develop a model of the contagious spread of information in a global-scale, publicly-articulated social network and show that a simple method can yield not just early detection, but advance warning of contagious outbreaks. In this method, we randomly choose a small fraction of nodes in the network and then we randomly choose a friend of each node to include in a group for local monitoring. Using six months of data from most of the full Twittersphere, we show that this friend group is more central in the network and it helps us to detect viral outbreaks of the use of novel hashtags about 7 days earlier than we could with an equal-sized randomly chosen group. Moreover, the method actually works better than expected due to network structure alone because highly central actors are both more active and exhibit increased diversity in the information they transmit to others. These results suggest that local monitoring is not just more efficient, but also more effective, and it may be applied to monitor contagious processes in global–scale networks.
“Are You at Peace?”
(American Medical Association (AMA), 2006) Steinhauser, Karen E.; Voils, Corrine I.; Clipp, Elizabeth C.; Bosworth, Hayden B.; Christakis, Nicholas A.; Tulsky, James
Background Physicians may question their role in probing patients’ spiritual distress and the practicality of addressing such issues in the time-limited clinical encounter. Yet, patients’ spirituality often influences treatment choices during a course of serious illness. A practical, evidence-based approach to discussing spiritual concerns in a scope suitable to a physician-patient relationship may improve the quality of the clinical encounter. Methods Analysis of the construct of being “at peace” using a sample of patients with advanced cancer, congestive heart failure, or chronic obstructive pulmonary disease. Descriptive statistics were used to compare response distributions among patient subgroups. Construct validity of the concept of being “at peace” was evaluated by examining Spearman rank correlations between the item and existing spirituality and quality-of-life subscales. Results Variation in patient responses was not explained by demographic categories or diagnosis, indicating broad applicability across patients. Construct validity showed that feeling at peace was strongly correlated with emotional and spiritual well-being. It was equally correlated with faith and purpose subscales, indicating applicability to traditional and nontraditional definitions of spirituality. Conclusions Asking patients about the extent to which they are at peace offers a brief gateway to assessing spiritual concerns. Although these issues may be heightened at the end of life, research suggests they influence medical decision making throughout a lifetime of care.
The Intramembrane Structure of Septate Junctions Based on Direct Freezing
(Company of Biologists, 1986) Kachar, B; Christakis, Nicholas A.; Reese, T.S.; Lane, N.J.
Smooth septate junctions from the midgut of the cricket, Acheta, and the horseshoe crab, Limulus, as well as Hydra-type septate junctions from the epidermis of Hydra have been studied by freeze-fracture after direct freezing using the liquid helium-cooled copper block/slam freezing method. The exoplasmic fracture face at both types of septate junction exhibits rows of closely packed but irregularly shaped intramembrane particles. Complementary to these particle rows, on the protoplasmic fracture face, are sharply defined grooves with a periodic variation in depth and width that was conspicuous in Hydra but less well defined in arthropods. The closely packed, irregular particles on the exoplasmic faces could represent plastically deformed portions of transmembrane proteins pulled through the bilayer during freeze-fracture. On the basis of this interpretation, the grooves on the protoplasmic faces represent a confluence of the bilayer disruptions occurring during fracturing. The structures observed here are different from those reported in replicas of glutaraldehyde-fixed and glycerol-cryoprotected tissue, in which the intramembrane junctional components partition with the protoplasmic face and often assume the appearance of continuous cylinders. This comparison illustrates some of the artifacts associated with freeze-fracturing and shadowing. On the basis of a comparison of freeze-fracture replicas and sections of lanthanum-infiltrated tissues, the relationship between intramembrane junctional components and intercellular septal elements is analysed.
Intimate partner violence norms cluster within households: an observational social network study in rural Honduras
(Springer Nature, 2016) Shakya, Holly B.; Hughes, D. Alex; Stafford, Derek; Christakis, Nicholas A.; Fowler, James H.; Silverman, Jay G.
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.
Parental Influence on Substance Use in Adolescent Social Networks
(American Medical Association (AMA), 2012) Shakya, Holly B.; Christakis, Nicholas A.; Fowler, James H.
Objective To evaluate the relationship between the parenting style of an adolescent's peers' parents and an adolescent's substance use. Design Longitudinal survey. Setting Adolescents across the United States were interviewed at school and at home. Participants Nationally representative sample of adolescents in the United States. Main Exposure Authoritative vs neglectful parenting style of adolescent's parents and adolescent's friends' parents and adolescent substance use. Main Outcome Measures Adolescent alcohol abuse, smoking, marijuana use, and binge drinking. Results If an adolescent had a friend whose mother was authoritative, that adolescent was 40% (95% CI, 12%-58%) less likely to drink to the point of drunkenness, 38% (95% CI, 5%-59%) less likely to binge drink, 39% (95% CI, 12%-58%) less likely to smoke cigarettes, and 43% (95% CI, 1%-67%) less likely to use marijuana than an adolescent whose friend's mother was neglectful, controlling for the parenting style of the adolescent's own mother, school-level fixed effects, and demographics. These results were only partially mediated by peer substance use. Conclusions Social network influences may extend beyond the homogeneous dimensions of own peer or own parent to include extradyadic influences of the wider network. The value of parenting interventions should be reassessed to take into account these spillover effects in the greater network.
Attitude and Self-reported Practice Regarding Prognostication in a National Sample of Internists
(American Medical Association (AMA), 1998) Christakis, Nicholas A.; Iwashyna, Theodore J.
Background Since prognostication appears increasingly important in clinical practice, especially in end-of-life care, we examined physicians' experiences and attitudes regarding it. Methods We mailed a survey to a national sample of 1311 internists, yielding 697 responses that were analyzed with multivariate models and other means. Findings were supplemented by qualitative comments from 162 physicians and by interviews with 20. Results On an annual basis, the typical internist addressed the question "How long do I have to live?" 10 times, withdrew or withheld life support 5 times, and referred 5 patients to hospice. Nevertheless, physicians disdain prognostication: 60.4% find it "stressful" to make predictions; 58.7% find it "difficult"; 43.7% wait to be asked by a patient before offering predictions; 80.2% believe patients expect too much certainty; 50.2% believe that if they were to make an error, patients might lose confidence; 89.9% believe they should avoid being too specific; and 56.8% report inadequate training in prognostication. With respect to the key concept of "terminal" illness, physicians on average believe that such patients should have 13.5±11.8 weeks to live, but responses varied substantially from 1 to 75 weeks. Conclusions Physicians (1) commonly encounter situations that require prognostication, (2) feel poorly prepared for prognostication, (3) find it stressful and difficult to make predictions, (4) believe that patients expect too much certainty and might judge them adversely for prognostic errors, and (5) vary in how they regard the key concept of being "terminally ill." These observations may have significant consequences for patient care.
Complexities in Prognostication in Advanced Cancer
(American Medical Association (AMA), 2003) Lamont, Elizabeth; Christakis, Nicholas A.
Predicting survival and disclosing the prediction to patients with advanced disease, particularly cancer, is among the most difficult tasks that physicians face. With the de-emphasis of prognosis in favor of diagnosis and therapeutics in the medical literature, physicians may have difficulty finding the survival information they need to make appropriate estimates of survival for patients who develop cancer. Quite separate from the challenge of estimating survival accurately, physicians may also find the process of disclosing the prognosis to their patients difficult. Using the vignette of a real patient with advanced cancer who far outlived her physician's prognostic estimate, we discuss clinical issues related to the science of prognosis in advanced cancer and the art of its disclosure.