This article examined the effects of a community-based genomic–epidemiologic study on residents of Nagahama, Japan regarding their attitudes toward the project and genetic testing.

Respondents who were aware of the contents of the study perceived their understanding of terminology to be high. This was contrary to our expectation that the awareness of the study contents did not correlate with their self-rated understanding terminology as Nagahama City and Kyoto University try hard to keep every citizen informed about the Nagahama study by providing leaflets several times to all houses [14]. One reason might be that participants in the Nagahama study could enhance their understanding of terminology through the study’s briefing paper, and another reason might be that those who were interested in genome studies could also attend symposia or science cafés because science communication activities are mainly accepted by those who are already interested in science and have positive attitudes toward science, as Gottweis [28] suggested.

Previous studies have shown that the public generally has positive attitudes toward genetic studies [15–19]. Similarly, the present study found that more than 80 % of the respondents were aware of the benefits of genetic studies. Those who were aware of the project’s contents and perceived their comprehension of the terminology well were more aware of the benefits than those who had lower awareness. This result supports the idea that experiences and familiarity with genetic testing are associated with positive attitudes toward it. In a nationwide study in Japan [17], those who had learned about genetics in school and had heard of the term “genetic testing” approved of the promotion of genomic studies. In Dutch studies [16, 23], the public attitude changed over time even though their experience with genetic testing had not increased. More people endorsed the ideas that “genetic knowledge helps people live longer” and “genetic study should be promoted” in 2010 than in 2002. They suggested that the public do not perceive neonatal and prenatal screening tests as genetic tests. However, there is a chance that the public unconsciously glances over genetic issues in today’s society. Condit [12] suggested that people accept a new technology as the natural order when it becomes familiar over time. Most citizens usually see genome studies as being outside of the natural order. The Nagahama study program was perceived as an extensive and free health check-up program that ultimately inspired 10,084 residents to become involved [14]. In this case, because of the number of participants, this method may be effective to familiarize the general public with genetic studies and its outcomes. Alhakami & Slovic [29] suggested that people tended to judge the benefits as high when they felt the activity was favorable, which may apply in the case.

Lids et al. [30] clarified that research participants have a “personal” frame, while researchers have a “science” frame. Therapeutic misconception arises not from a lack of information but from a difference in cognitive frame. Therefore, they posit that scientific reframing of what is involved in a clinical trial is necessary. The Nagahama study has been promoted by the catchphrase “for your children and grandchildren” to avoid a “science” frame. One third of citizens live in their native community and one fourth of citizens live with their extended family consisting of more than three generations of family members [31]. Belief of the study’s benefits for their children and grandchildren may attract them to participate and become aware of the benefits of the genome study.

Almost half of the respondents had a positive attitude toward donating their DNA for drug susceptibility genetic testing, while approximately 30 % could not decide and roughly 20 % had a negative attitude. A logistic regression analysis was conducted to explore the factors associated with willingness to participate in drug susceptibility genetic testing. According to the results, both males and females who had positive attitudes toward such testing had high levels of self-rated understanding of the terminology and a high degree of awareness of the benefits of genetic studies.

Kobayashi and Satoh [32] used the Internet to explore Japanese attitudes toward pharmacogenomics research. Of their respondents, 45.3 % had a positive attitude and 46.3 % were neutral toward participating in pharmacogenomics research when taking medications. However, the willingness to participate increased to 61.7 % positive and decreased to 30.6 % neutral when experiencing severe adverse drug reactions. The proportion of respondents who refuse to participate was similar in both scenarios (8.3 % vs. 7.6 %, respectively) in their study. The reason for the disparity between Kobayashi’s study and ours could be the use of the Internet and a correspondingly higher interest in scientific issues compared with those in the present study.

Haga et al. [33] investigated the American public’s attitude toward pharmacogenomics research. Of their respondents, 92 % had positive attitudes toward testing to assist with drug selection and 73 % approved of testing to predict mild side effects. Respondents in their study were markedly more positive compared with respondents in our and Kobayashi’s studies [32]. Ishiyama et al. [17] assume that Japanese tend to be prudent in decision-making. Our results support them.

In addition, 78 % of respondents in the Haga et al. stated they were unwilling to undergo drug susceptibility genetic testing if their DNA or test results would be shared without their permission [33]. The authors suggest that the respondents might be unaware that federal law bans genetic discrimination by health insurers or employers, which may have effected their results. In the present study, the belief that companies or government bodies may use genetic information was not associated with willingness toward testing. Nagahama city government enacted an ordinance, the “Nagahama Rule,” to manage the Nagahama study. The mission was to prioritize citizens’ dignity and that might have encouraged citizens’ trust in the study.

Awareness of the project contents was associated with the willingness to participate in drug susceptibility genetic testing in males but not in females. According to a review by the Office of Science and Technology and the Wellcome Trust [34], the supporters of science tend to be self-confident, and they generally have trust in the government and higher authorities. Recruitment for the Nagahama study was achieved through various public information channels as well as word-of-mouth communications. Thus, males who were inactive in their respective community associations were less aware of the Nagahama study, whereas females were more aware because volunteering was a routine community activity for them [14]. Conversely, males who were active in their community associations generally trusted regulatory systems. This might explain why the positive attitudes toward drug susceptibility genetic testing associated with the awareness of Nagahama study were only seen in males. For females, just being aware of community-based genome studies did not change the willingness to participate in drug susceptibility genetic testing. Females may be able to bring themselves to donate DNA toward genetic testing if they feel familiar with the genetic terminology. Condit [12] suggests that people tend to perceive a certain category as the natural state of affairs when the given category is familiar to them. For example, people may agree to donate their DNA for drug susceptibility genetic testing without reluctance if their family members and if trusted confidants recommend such involvement. Moreover, as Lids et al. suggest, it is necessary to provide information appropriate to the public’s cognitive frame of personal needs for drug susceptibility genetic testing. As genome cohort study is coherently the project to promote public health through the development of medicine within a “science frame,” while “extensive and free health check-up,” “study for your children and grandchildren,” and “genetic testing for revealing of association between drug effectiveness or drug adverse reaction and genomic markers” are different things within a “personal frame.” Timely and consecutive communication is required because the results are obtained a long time after participants provide consent for the study.

The present study has several limitations. First, participants were dichotomized into respondents who were aware of the project’s contents and those who didn’t know about the study at all; however, this approach may have introduced bias. In fact, those who were aware of the project contents were generally involved in community activities, were health conscious, and had trust in the government. This self-selecting bias may have altered the results.

Second, this study itself may become a public relation tool for the Nagahama study, and consequently, influence respondents’ attitudes toward genetic research. However, we found that the attitude of subjects who were aware about the study contents before the study period was significantly different from that of subjects who did not know about the study content before the study period. This difference persisted even if subjects who were unaware of the contents gained knowledge during the study period.

Third, self-rated understanding of terminology may not indicate true comprehension. According to Ladwig et al. [24], perceived knowledge affects understanding in a different way than factual knowledge. Perceived knowledge could be influenced by specific heuristics, whereas factual knowledge could not. Hypothetically, perceived knowledge is more supportive of technology. Future studies should investigate the differences of influence between perceived and factual knowledge for public understanding of genome study. Finally, this study involved cooperation between the local government and a university, which is a rare scenario in Japan. Thus, the results of such collaboration may not apply to other communities.

It is necessary to conduct future research about the gap between the awareness of the benefits of genome study and the willingness to undergo drug susceptibility genetic testing. We hope to conduct a series of interviews to explore the reasons for negative attitudes toward drug susceptibility genetic testing, which might be a potential abhorrence, differences in context, the misconception as specific treatment for serious diseases but general diagnose, lack of information, or a matter of communication.