Japanese Young Adults Research Articles

Internet-Based Cognitive Behavior Therapy for Stress and Anxiety among Young Japanese Adults: A Preliminary Study

In the present study, we examined the effect of an internet cognitive behavior therapy (ICBT) program on anxiety, stress, and depressive symptoms in university students. Data were analyzed for 17 participants undergoing ICBT and 11 control group participants. An ANOVA of intention-to-treat analysis and per protocol (PP) analysis indicated that the interaction between group and measurement time was significant for the state–trait anxiety inventory (STAI) scores and that idiosyncratic anxiety was significantly improved. Through the results of PP, a moderate effect size for changes in STAI scores in the intervention group was observed (d = 0.62) based on Cohen’s (1988) classifications. A large effect was also observed for improvements in idiosyncratic anxiety (d = 0.91). Based on the results of the analyses, a significant interaction was observed for the STAI scores. In the intervention group, STAI scores and individual anxiety were significantly reduced after implementing the ICBT program. It was suggested that the ICBT program may positively influence thinking about anxiety and stress from an objective viewpoint.

Japanese university students' difficulty in living and its association with suicidal ideation.

In this study, we investigated (1) Japanese university students' actual "difficulty in living" and (2) its association with suicidal ideation. The Difficulty in Living Questionnaire was administered to 547 Japanese university students. Results revealed that 37.5% of the students felt difficulty in living, and 21.0% had ongoing suicidal ideation. An exploratory factor analysis resulted in a three-factor model, and multiple regression analysis showed that factors "external self-insufficiency" and "feeling of emptiness" significantly predicted suicidal ideation. To prevent young Japanese adults from committing suicide, increasing their self-affirmation and feelings of value among other people is crucial.

Prevalence of Femoroacetabular Impingement Features in Japanese Young Adults without Symptoms: Hip Joint Morphology Using Radial Reformation from Computed Tomography

Prevalence of Femoroacetabular Impingement Features in Japanese Young Adults without Symptoms: Hip Joint Morphology Using Radial Reformation from Computed Tomography

Trends in heterosexual inexperience among young adults in Japan: analysis of national surveys, 1987\u20132015

BackgroundIt has been suggested that an increasing number of Japanese adults remain sexually inexperienced; however, no study has assessed this issue using nationally representative data.MethodsWe used data from seven rounds of the National Fertility Survey of Japan, 1987–2015, and included adults aged 18–39 years (18–34 years in the 1987 survey) in the analyses (sample size 11,553–17,850 [1987–2010]; response rate 70.0–92.5%). For each survey year, sex and age group, we estimated the age-adjusted prevalence of heterosexual inexperience, defined as reporting no experience of sexual intercourse with someone of the opposite sex. We used logistic regression, adjusted for age, to identify factors associated with heterosexual inexperience in the 2010 survey. Information about same-sex sexual experience was not available.ResultsBetween 1992 and 2015, the age-standardized prevalence of heterosexual inexperience in adults aged 18–39 years increased from 21.7 to 24.6% for women (p-values for linear and quadratic trend < 0.05) and from 20.0 to 25.8% for men (p-values for trend < 0.05). Among those aged 30–34 years, the prevalence was 6.2% in 1987 and 11.9% in 2015 for women (p-values for trend ≥0.05) and 8.8% (1987) and 12.7% (2015) for men (p-values for trend ≥0.05). Among those aged 35–39 years, prevalence increased from 4.0% in 1992 to 8.9% in 2015 among women (p-values for trend < 0.05). The corresponding numbers for men in the same age group were 5.5 and 9.5%, respectively (p-values for trend ≥0.05). Among men aged 25–39 years, unemployment, temporary/part-time employment and lower income were associated with heterosexual inexperience.ConclusionsThe proportion of young Japanese adults with no experience of heterosexual intercourse had increased in the past two decades. Among adults in their thirties, around one in ten had no heterosexual experience. Unemployment, temporary/part-time employment and low income were associated with heterosexual inexperience among men. Further research is needed on the factors contributing to and the potential public health and demographic implications of the high proportion of the Japanese population that remains sexually inexperienced well into adult age.

Factors Affecting Evacuation Behavior in Cases of Toxic Gas Release: Questionnaire Survey of Korean and Japanese Younger Adults

Factors Affecting Evacuation Behavior in Cases of Toxic Gas Release: Questionnaire Survey of Korean and Japanese Younger Adults

Relationship of Lifestyle Habits with Sleep Quality among Japanese in Their 20s

The purpose of this study was to analyze the effects of lifestyle on sleep quality in young Japanese adults. A cross-sectional study was conducted on the web. We analyzed 637 eligible subjects (316 men and 321 women) aged 20 - 29 years. Information on diet and individual lifestyle characteristics, including sleep quality, which was assessed using the Pittsburgh Sleep Quality Index Japanese version (PSQI-J). Results were obtained by participants completing an online questionnaire. The participants were divided into two groups based on whether they were students (“student group”) or not (“not student group”). The participants with a PSQI-J global score of 6 or higher were evaluated as low-sleep-quality. Logistic regression analyses were performed to evaluate associations of lifestyle habits with low-sleep-quality. Logistic regression analyses were applied for “student group” and “not student group”. The results showed that days of eating out at dinner (OR: 1.11, CI: 1.00 - 1.22) and skipping dinner (OR: 1.21, CI: 1.05 - 1.42) were significant and independent predictors for low-sleep-quality among the “not student group”. There were no significant and independent predictors for low-sleep-quality among “student group”. Our results suggested that excessive intake by eating out and deficient intake by skipping dinner might lead to a high PSQI-J score. It is necessary for young people to receive education on the importance of cooking their own meals for traditional and daytime eating. The implication of this study lies in the fact that we have analyzed the effects of lifestyle habits on quality of sleep.

The level of salivary lactate dehydrogenase as an indicator of the association between gingivitis and related factors in Japanese university students.

The aim of this study was to investigate the association between the presence of gingivitis estimated using the salivary level of lactate dehydrogenase (LD) and related factors in young Japanese adults. Data from 1,915 participants (21.4 ± 2.5 years) were analyzed. Unstimulated saliva was collected from each participant and the salivary LD level was evaluated using a commercially available test kit with an integer scale ranging from 1 to 10. Gingivitis was defined as the LD level of ≥8. The number of permanent teeth, the simplified oral hygiene index (OHI-S), the presence of partially erupted molars and body mass index were recorded. Additionally, participants answered a questionnaire. The percentage of male participants, the number of permanent teeth, the OHI-S and the presence of partially erupted molars were higher, whereas the proportion receiving dental check-ups was lower in the gingivitis group (n = 88, 4.6%) than in the healthy group. Logistic regression analysis showed that gingivitis was significantly associated with OHI-S (OR: 2.68, 95% CI: 1.94-3.69) and receiving dental checkups (OR: 0.31, 95% CI: 0.10-0.99). The present findings indicated that the OHI-S and receiving dental checkups were significantly associated with gingivitis, as assessed by the salivary LD level, in this cohort.

Investigating Multidimensional Interoceptive Awareness in a Japanese Population: Validation of the Japanese MAIA-J.

The Multidimensional Assessment of Interoceptive Awareness (MAIA) is a self-report instrument to assess relevant dimensions of bodily awareness. The aim of this study was to offer a Japanese version and adaptation of the MAIA (MAIA-J), as well as to analyse its psychometric properties in a Japanese population. The English MAIA was systematically forward and backward translated by bi-lingual Japanese experts; additionally, content validity aspects regarding language were discussed by a panel of experts. The MAIA-J was administered to 390 Japanese young adults (age: 20.3 ± 2.2), 67.7% women and 32.2% men. Exploratory factor analysis (EFA) reduced the questionnaire from 32 to 25 items and from 8 to 6 factors (Noticing, Not-Distracting, Attention Regulation, Emotional Awareness, Body Listening, and Trusting). The Japanese version showed appropriate indicators of construct validity and reliability, with Cronbach's α between 0.67 and 0.87 for the 6 MAIA-J dimensions. The findings demonstrate that MAIA-J has a slightly different factor structure compared to the original English MAIA. Results are discussed with respect to cultural differences. However, the study results support acceptable reliability of the MAIA-J in the Japanese sample, warranting its use for future studies with Japanese populations.

Perceived Usefulness of Emoticons, Emojis, and Stickers in Text Messaging

In text-based communication, which lacks nonverbal cues, various techniques for expressing communicative intent are now available. Most prominently used are emoticons, emojis, and stickers. Although previous studies have separately examined emoticons and emojis, few have compared their features, and also included comparison with stickers. The authors conducted a survey targeting 300 Japanese young adults to investigate the features of emoticons, emojis, and stickers from the viewpoint of their perceived usefulness. The authors also examined the effects of gender and text-messaging dependency on ratings of the perceived usefulness of these graphical symbols. This study revealed a detailed feature list for each type of symbol. The existence of characteristic roles for each type of symbol is discussed. This study also confirmed the effects of gender and text-messaging dependency on symbol usefulness ratings.

Associations between problematic Internet use and psychiatric symptoms among university students in Japan.

Research on the adverse effects of Internet use has gained importance recently. However, there is currently insufficient data on Japanese young adults' Internet use, so we conducted a survey targeting Japanese university students to research problematic Internet use (PIU). We also investigated the relationship between PIU and multiple psychiatric symptoms. A paper-based survey was conducted at five universities in Japan. Respondents were asked to fill out self-report scales regarding their Internet dependency using the Internet Addiction Test (IAT). Sleep quality, attention-deficit hyperactivity disorder (ADHD) tendency, depression, and anxiety symptom data were also collected based on respective self-reports. There were 1336 responses and 1258 were included in the analysis. The mean IAT score (± SD) was 37.87 ± 12.59; and 38.2% of participants were classified as PIU, and 61.8% as non-PIU. The trend level for young women showed that they were more likely to be classified as PIU than young men (40.6% and 35.2% respectively, P = 0.05). Compared to the non-PIU group, the PIU group used the Internet longer (P < 0.001), had significantly lower sleep quality (P < 0.001), had stronger ADHD tendencies (P < 0.001), had higher Depression scores (P < 0.001), and had higher Trait-Anxiety scores (P < 0.001). Based on multiple logistic regression analyses, the factors that contributed to an increased risk of PIU were: being female (odds ratio [OR] = 1.52), being older (OR = 1.17), having poor sleep quality (OR = 1.52), having ADHD tendencies (OR = 2.70), having depression (OR = 2.24), and having anxiety tendencies (OR = 1.43). We found a high PIU prevalence among Japanese young adults. The factors that predicted PIU were: female sex, older age, poor sleep quality, ADHD tendencies, depression, and anxiety.

Secure base script and psychological dysfunction in Japanese young adults in the 21st century: Using the Attachment Script Assessment.

The universality of secure base construct, which suggests that one's use of an attachment figure as a secure base from which to explore the environment is an evolutionary outcome, is one of the core ideas of attachment theory. However, this universality idea has been critiqued because exploration is not as valued in Japanese culture as it is in Western cultures. Waters and Waters (2006) hypothesized that one's experiences of secure base behaviors are stored as a script in memory, and developed a narrative assessment called the Attachment Script Assessment (ASA) to evaluate one's secure base script. This study examined the validity of the ASA and the utility of secure base concept in Japanese culture. A sample of Japanese young adults (N = 89; M = 23.46; SD = 3.20; 57% = females) completed both the ASA and self-report questionnaires. The results revealed that the ASA score was associated with two dimensions of self-report questionnaires assessing parent-youth attachment relationships (trust and communication). The ASA score was not related to Japanese cultural values (amae acceptance, interdependent self-construal, and low independent self-construal). However, a low ASA score was related to a psychological dysfunction in the Japanese cultural context; hikikomori symptoms, which are defined as a desire to remain in his or her own room and his or her understanding of this behavior in other people. We concluded that since hikikomori can be interpreted as an extreme inhibition of exploration, the association between low secure base script and hikikomori symptoms suggests the utility of secure base construct in Japan. (PsycINFO Database Record

Associations of Current Wheeze and Body Mass Index with Perennial and Seasonal Allergic Rhinitis in Young Adults

Background: The coexistence of asthma and allergic rhinitis (AR) and its distinct association with obesity have been reported. However, few studies have differentiated the two types of AR, i.e., perennial (PAR) and seasonal AR (SAR), with regard to their associations with asthma and obesity. The aim of this study was to evaluate the coexistence of current wheeze and two types of AR and the impact of body mass index (BMI) on these two conditions in Japanese young adults. Methods: First-year students from Hokkaido University were enrolled into this study from 2011 to 2016. A questionnaire survey including the prevalence of current wheeze, PAR, and SAR every year for 11,917 nonsmoking young adults was conducted. The difference in the impact of current wheeze and BMI on these two types of AR was separately evaluated. Results: Although both PAR and SAR were significantly associated with current wheeze, the impact of these two AR types on current wheeze was different (OR for PAR = 2.46 vs. OR for SAR = 1.29). When we classified all of the subjects into 4 groups with or/and without the two types of AR, the prevalence of current wheeze was significantly higher in subjects with PAR than in those without PAR (p < 0.001). However, the prevalence of current wheeze did not differ between subjects with or without SAR. Multinomial regression analyses showed that the association of wheeze with PAR and/or SAR was stronger compared to that of wheeze with SAR without PAR. The prevalence of PAR was not associated with BMI. Contrarily, a low BMI was significantly associated with a high SAR prevalence (p < 0.05). Conclusion: Comparisons between PAR and SAR showed that the conditions are differentially associated with current wheeze and BMI.

Immunogenicity, safety, and tolerability of a recombinant hepatitis B vaccine manufactured by a modified process in healthy young Japanese adults

ABSTRACTHepatitis B vaccines are highly effective in preventing hepatitis B virus infection and have been included in the national immunization program of Japan since 2016. Heptavax®-II is one of two hepatitis B vaccine products licensed in Japan, and its manufacturing process is being modified to reduce variability of manufacturing and optimize immunogenicity. In this study (NCT01463683), the immunogenicity and safety of a modified-process hepatitis B vaccine (mpHBV) were compared to those of the licensed Heptavax®-II. Overall, 722 Japanese adults aged 20-to-35 years old were randomized in a 3:3:1 ratio to either the mpHBV subcutaneous (SC) injection group (mpHBV SC), the Heptavax®-II SC injection group (Heptavax®-II SC), or the mpHBV intramuscular (IM) injection group (mpHBV IM). All participants received a 3-dose series of either mpHBV or Heptavax®-II at Day 1, Month 1, and Month 6. Serum antibody to hepatitis B virus surface antigen (anti-HBs) was assayed on Day 1 prior to the first vaccination and Month 7 (1 month Postdose 3). Seroprotection rates in mpHBV SC were non-inferior to that in Heptavax®-II SC and anti-HBs geometric mean titers were numerically higher in mpHBV SC as compared to Heptavax®-II SC. The incidences of injection-site and systemic adverse events (AEs) observed in mpHBV SC were comparable to those in Heptavax®-II SC, except for erythema which was higher in mpHBV SC than in Heptavax®-II SC. Most injection-site and systemic AEs were mild-to-moderate in intensity and there were no reports of vaccine-related serious AEs in any group. IM administration of mpHBV was well-tolerated and more immunogenic compared to SC administration. In conclusion, mpHBV and Heptavax®-II were well-tolerated and elicited satisfactory immune responses for the prevention against hepatitis B virus-associated diseases.

Exploring Potential Factors in Sticker Use Among Japanese Young Adults

In text-based communication, people can now use not only emoticons and emoji, but also graphical symbols called stickers. This study focused on the use of stickers in text-based communication. A questionnaire asking subjects to individually rate the perceived usefulness of 25 features of stickers was prepared and used in a survey targeting 211 Japanese college students. The authors then explored potential factors in the roles of stickers. The study revealed three potential roles of stickers: “easy transmission of subtle nuances and nonverbal cues,” “abundant and versatile expressions that can be substituted for text messages,” and “changing the topic, flow, or rationale of the interaction.” The authors examined the effects of gender and text messaging dependency on these roles. Results showed significant effects of dependency in all roles, but effects of gender were seen in only “abundant and versatile expressions that can be substituted for text messages.”

Sex differences in insulin and glucagon responses for glucose homeostasis in young healthy Japanese adults.

It has been reported that glucose responses during the oral glucose tolerance test differ between healthy women and men. However, it remains unknown what factors contribute to these differences between the sexes. The present study analyzed the insulin and glucagon responses during the oral glucose tolerance test in 25 female and 38 male healthy young adults aged 22–30 years. The plasma glucose levels at 120 min were significantly higher in women than men. Insulin secretion was significantly greater at 30, 90 and 120 min from baseline in women than men. Glucagon suppression was greater at 30 and 120 min from baseline in men than women when determined by a sandwich enzyme‐linked immunosorbent assay glucagon kit. These results suggest that the differences in glucose responses during the oral glucose tolerance test are mediated by the difference between the sexes in bi‐hormonal responses in healthy individuals.

Effect of Eating out on Quality and Quantity of Sleep among Japanese in Their 20s

The purpose of this study was to analyze the effects of eating out or skipping meals on the quality or quantity of sleep in young Japanese adults. We analyzed 584 eligible subjects (283 men and 301 women) aged 20 - 29 years. Information on diet and individual lifestyle characteristics, including sleep quality, which was assessed by the Pittsburgh Sleep Quality Index Japanese version (PSQI-J), were obtained by participants completing an online questionnaire. Kendall’s tau coefficient was used to measure the ordinal association between diet and sleep quality. The Mann-Whitney U test was performed to evaluate differences in sleep quality by frequency of eating out and frequency of skipping meals. The results revealed a significant difference in sleep duration and PSQI-J score between people who eat out >2 times a week (“high restaurants group”) and those who do not (“low restaurants group”). Furthermore, whereas the mean sleep duration in the “high restaurants group” was 6.59 hours, the mean sleep duration in the “low restaurants group” was 6.90 hours (p = 0.007). The PSQI-J score was significantly higher in the “high restaurants group” than in the “low restaurants group” (4.91 versus 4.37, p = 0.006). Significant differences were also evident in the test’s component scores: C2, C3, and C7. No significant difference was found in sleep duration and PSQI-J score between the groups in terms of frequency of skipping meals (breakfast, lunch, and dinner). Our results suggested that excessive intake by eating out more than twice a week may lead to short sleep duration and high PSQI-J score.

Prevalence of sleep-disordered breathing in Japanese medical students based on type-3 out-of-center sleep test

BackgroundSleep-disordered breathing (SDB), especially obstructive sleep apnea disorder (OSA), is thought to mainly affect men over the age of 40. Following findings that Asian people are more likely to experience severe OSA, regardless of obesity, we investigated the prevalence of SDB and OSA in a larger sample and in more younger age groups than those described in previous reports. MethodsBetween 2011 and 2016, 487 medical students (358 males, mean age 24.8 ± 1.9 years; 129 females: mean age 23.8 ± 1.6 years) underwent an out-of-center sleep test using a type-3 portable monitor. The results were analyzed visually. ResultsThe mean ± standard deviation of the respiratory event index (REI: events/hour of monitoring) was 5.4 ± 6.7 (6.7 ± 7.5 in male participants, 2.6 ± 2.1 in female participants). There were 170 participants (36.6%) with an REI≥5, including 158 male participants (46.9%) and 12 female participants (9.1%). SDB or undefined OSA with low REI (15 > REI≥5) was observed in 141 participants (30.4%), defined OSA with moderate REI (30 > REI≥15) in 19 participants (4.1%), and defined OSA with high REI (REI≥30) in 10 participants (2.2%). Among the male students, 129 had low REI (38.3%), 19 had moderate REI (5.6%), and 10 had high REI (3.0%). All female participants with OSA events (9.4%) had a low REI. ConclusionsThe prevalence of OSA in Japanese young adults, especially males under 30 years old, is similar or even higher than that in older age groups described previously. Thus, an aggressive sleep study for SDB might be necessary for the younger generation in the Asian population.

An Evaluation of Soft Tissue Facial Profile in Japanese Young Adults with Normal Occlusion Using Proportional Analysis

An Evaluation of Soft Tissue Facial Profile in Japanese Young Adults with Normal Occlusion Using Proportional Analysis

The reliability and validity of the Temporal Focus Scale in young Japanese adults

Temporal focus is understood as one component of an individual's time perspective, and is defined as the attention individuals devote to thinking about the past, present, and future. The 12-item Temporal Focus Scale is comprised of 3 factors (past, current, and future focus). In this study, we examined the reliability and validity of Temporal Focus Scale scores in a sample of 977 young Japanese adults, aged 18–24years old. The hypothesized 3 factor structure was confirmed, although there were problems with item number 10. Internal consistency estimates for scores without item 10 were over 0.70, and seven-week test-retest reliability was also adequate. To verify the convergent and discriminant validity, we tested the relationship between scores and time perspective, time attitudes, life satisfaction, self-esteem, and career confidence. Results of correlational analyses supported our hypotheses. Specifically, a future focus was more strongly correlated with career efficacy than a past or current focus.

Reduced orbitofrontal cortical volume is associated with interdependent self-construal

Interdependent self-construal refers to a view of the self as embedded in relationships with others. Prior work suggests that this construal is linked to a strong value placed on social obligations and duties. Interdependent people are therefore cognitively attuned to others and various social events in their surroundings while down-regulating their personal goals. In the present work, we examined whether structural properties of the brain predict interdependent self-construal. We performed a structural magnetic resonance imaging on 135 Japanese young adults while assessing (i) independent and interdependent self-construals and (ii) the degree to which individuals form vivid images of external objects (object imagery). The cortical volume of the orbitofrontal cortex (OFC) (a core cortical region responsible for value-based decisionmaking and, thus, inherently involved in personal goals and desires) inversely predicted interdependent self-construal. Further analysis found that the highest level of interdependent self-construal is achieved when those who are relatively low in the OFC volume are simultaneously high in object imagery, consistent with previous evidence that interdependence, as realized via obligation and duty, requires both the reduced self-interest and vigilant cognitive attunement to environmental context.