Original Research Article Impact of Lifestyle Changes on Stress in a Modernizing Rural Population in Hainan Island, China AKI YAZAWA, 1 * YOSUKE INOUE, 1 DANDAN LI, 2 JIANWEI DU, 2 YUMING JIN, 2 YAN CHEN, 2 MASARU NISHITANI, 3 CHIHO WATANABE, 1 AND MASAHIRO UMEZAKI 1 1 Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan 2 Hainan Center for Disease Control and Prevention, Haikou, Hainan 570203, China 3 National Museum of Japanese History, Sakura, Chiba 285-8502, Japan Objective: Little is known about inter-individual variation in psychological stress in modernizing rural populations in developing countries. The objective of this study was to investigate the association between Epstein-Barr virus (EBV) antibody titer, a biomarker of psychological stress, and lifestyle parameters in rural communities in Hainan Island, China. Methods: EBV antibody titer was measured in dried blood spot (DBS) samples collected from 240 adults living in rural communities in Hainan Island. Measures of two major lifestyle changes in rural areas of Hainan Island, i.e., diet and commercial goods possession, were examined by using information on the weekly frequency of pork consumption and monthly mobile phone fees. Both parameters were standardized to create two composite scores: a total affluence index (TAI—the sum of these scores), and an investment tendency index (ITI—the difference between them). Least- squares regression analysis was used to investigate the association between EBV antibody titer and these lifestyle parameters. Results: A positive association was found between the frequency f pork consumption and EBV antibody titer (P 5 0.040), whereas a negative association was found between mobile phone fees and EBV antibody titer (P 5 0.028). A neg- ative association was also observed between ITI and EBV antibody titer (P 5 0.002) after adjusting for the effect of TAI. Conclusion: Psychological stress among local residents was linked to the type of lifestyle changes they had experi- enced, where the adoption of a more market-oriented lifestyle, irrespective of current affluence, was associated with less psychological stress. Am. J. Hum. Biol. 00:000–000, 2013. V C 2013 Wiley Periodicals, Inc. In recent decades, rapid economic growth in developing countries has brought about drastic changes in people’s lifestyles. Such changes have been observed at both the individual level [e.g., changes in diet, physical activity and disease profiles (Monda et al., 2007)] and societal level [e.g., changes in infrastructure, land use, transpor- tation planning and urban design (Popkin, 2001)]. The combined effects of this process of change have been termed “modernization.” It has been suggested that modernization is a psycho- logical stressor (Brown, 1982; Jenner et al., 1987; Pearson et al., 1993). For example, using the urinary concentra- tion of catecholamine as a biomarker of psychological stress, Pearson et al. (1993) showed that Samoan adults who resided in Honolulu, the provincial capital of Hawaii, the United States of America, had higher levels of psycho- logical stress than their counterparts living in rural West- ern Samoa. Similarly, McDade et al. (2000a) used another biomarker of psychological stress—Epstein-Barr virus (EBV) antibody titer—to highlight how urban children and adolescents had higher psychological stress than their rural peers in Western Samoa. As yet, however, little attention has been paid to whether there might be inter-individual variation in psy- chological stress within modernizing rural populations. This may be an important gap in our knowledge especially as some evidence suggests that the modernization process has induced diversification in the lifestyle of individuals (e.g., types of activity and diet), even within rural areas (Adelman and Morris, 1973). Moreover, social comparison theory provides a mechanism for explaining how diversifi- cation within what were once homogenous communities might play a role in deteriorating psychological health. It highlights how the perception of an undesirable difference in lifestyle parameters with other community members, especially those whom a person believes to be comparable to him or herself (defined as a reference group), may be detrimental in terms of increasing the psychological stress of those who fare worse in the comparison (Fes- tinger, 1954). Given this, investigating different types of lifestyle in such an environment might shed light on the impact that modernization has on local residents’ psycho- logical stress due to the changes it brings about in differ- ent forms of behavior (i.e., lifestyle). This study was conducted among rural communities in Hainan Island, China. People in the rural communities in this location lived generally impoverished lives until the 1990s. However, from the late 1990s onwards rapid eco- nomic development occurred there and the communities as a whole became much wealthier. One result of this was that people’s lifestyles increasingly diversified. The authors’ observations among the local communities on the Contract grant sponsor: The Japan Society for the Promotion of Science; Contract grant number: A Grant-in-Aid for Scientific Research (KAKENHI project no. 20401011, 11J02876) and Institutional Program for Young Researcher Overseas Visits (International Training Program to Pro- duce New Leaders in Global Health). *Correspondence to: Aki Yazawa, Department of Human Ecology, Grad- uate School of Medicine, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. E-mail: aki-y@humeco.m.u-tokyo.ac.jp Received 20 June 2013; Revision received 10 September 2013; Accepted 10 September 2013 DOI: 10.1002/ajhb.22467 Published online 00 Month 2013 in Wiley Online Library (wileyonlinelibrary.com). V C 2013 Wiley Periodicals, Inc. AMERICAN JOURNAL OF HUMAN BIOLOGY 00:00–00 (2013)