Isa Okajima

Insomnia as a risk for depression: A longitudinal epidemiologic study on a Japanese rural cohort

OBJECTIVES To determine (1) whether insomnia is a factor related to the presence or persistence of depression for 2 years in the Japanese population and (2) which component of insomnia is associated with the presence of depression for 2 years in a rural cohort. METHOD This is a community-based longitudinal study. Two thousand eight hundred twenty-five people aged 20 years or older were evaluated at baseline, and of those participants, 1,577 (56%) were reevaluated after 2 years. During both surveys, the participants were asked to describe demographic variables and to fill out self-rating scales of insomnia (Pittsburgh Sleep Quality Index [PSQI]) and depressive symptoms (Center for Epidemiologic Studies Depression Scale). RESULTS The results of a multiple logistic regression analysis showed that depression (OR = 6.0; 95% CI, 4.4-8.0) and insomnia (OR = 2.1; 95% CI, 1.5-2.8) at baseline were significantly associated with the presence of depression at the follow-up. Most of the PSQI subscales, except for sleep duration and habitual sleep efficiency, were significantly associated (P < .01) with the presence of depression at the follow-up. In addition, the new appearance and repeated existence of depression at the follow-up were related to persistent insomnia (adjusted ORs = 7.0 and 3.3 [P < .001], respectively). A result of the receiver operating characteristic curve showed that persons with insomnia whose PSQI scores exceeded 8 points at the baseline were most likely to still have insomnia at the follow-up (cutoff point = 7.5). CONCLUSIONS On the basis of our results in a Japanese population, insomnia with high severity level could be a risk factor for the presence/persistence of depression in the long-term prognosis.

Correlations among insomnia symptoms, sleep medication use and depressive symptoms

Aim:  To elucidate the factors associated with insomnia symptoms and the use of sleep medication, and the correlations among insomnia symptoms, sleep medication use and depressive symptoms in the general population.

Validation of the Japanese version of the Ford Insomnia Response to Stress Test and the association of sleep reactivity with trait anxiety and insomnia

OBJECTIVE Our study was conducted to validate the Japanese version of the Ford Insomnia Response to Stress Test (FIRST-J) and to clarify the association of the measure with trait anxiety and insomnia in healthy subjects and insomnia patients. METHODS We studied 161 healthy subjects and 177 insomnia patients who completed the FIRST-J, Pittsburgh Sleep Quality Index (PSQI), Athens Insomnia Scale (AIS), and State-Trait Anxiety Inventory-Trait (STAI). The healthy subjects and the insomnia patients were classified, respectively, into two groups with high FIRST-J and low FIRST-J scores (divided by the median value of healthy subjects). RESULTS Cronbach α coefficients of the FIRST-J in the insomnia patients and healthy subjects were 0.89 and 0.87, respectively. Factor analysis revealed that the FIRST-J had a single-factor structure. The FIRST-J score significantly correlated with all other measures in the healthy subjects, though the score only correlated with the score of the STAI in the insomnia patients. The healthy subjects with high FIRST-J scores showed higher scores of the AIS and STAI than those with low FIRST-J scores. Furthermore, insomnia patients had a higher total score of the FIRST-J than the healthy subjects. CONCLUSIONS The FIRST-J is an important tool for assessing vulnerability to insomnia.

A two-year follow-up study on the symptoms of sleep disturbances/insomnia and their effects on daytime functioning

OBJECTIVE This study attempts to identify changes in the symptoms of sleep disturbances/insomnia over a two-year course and their effects on daytime functioning. METHODS We administered two population-based epidemiological surveys in 2005 and 2007 to participants from rural Japan. RESULTS In the first survey, 30.7% of the subjects reported sleep disturbances/insomnia. Among them, 60.9% reported sleep problems at the two-year follow-up. A comparison of sleep disturbances/insomnia, and subjective daytime functioning measures between the new incident cases and persistent poor sleepers revealed that the total score of persistent poor sleepers was significantly lower than that of new incident cases on the Pittsburgh Sleep Quality Index and physical quality of life (QoL) but not mental QoL. Longitudinal comparisons of the symptoms of sleep disturbances/insomnia in persistent poor sleepers revealed that sleep efficiency was significantly worse at follow-up. Exacerbation of the symptoms of sleep disturbances/insomnia at follow-up was observed in mild but not severe cases. CONCLUSIONS Sleep efficiency progressively worsens over time, and physical QoL can deteriorate as sleep disturbances/insomnia become chronic. Since the symptoms of sleep disturbances/insomnia and their daytime effects are exacerbated even in mild cases, early intervention and treatment are necessary.

Anxiety symptoms among adolescents in Japan and England: their relationship with self‐construals and social support

Background: Most of our knowledge about anxiety in adolescents has come from studies conducted in Western countries. Little is known about the extent to which these results can be generalized to those who live in other cultures. The main aim of this study was to compare the frequency and correlates of anxiety symptoms among adolescents in Japan and England. Method: A total of 689 adolescents (338 from England and 351 from Japan), aged 12–17 years, took part in this research. They completed a set of questionnaires which were used to measure DSM‐IV anxiety disorder symptoms, general difficulties and positive attributes, self‐construals, and social support. Results: Adolescents in England reported significantly higher levels of anxiety symptoms than adolescents in Japan. In both countries, independent self‐construal was negatively associated with anxiety symptoms, while interdependent self‐construal was positively associated with anxiety. However, the magnitude of this relationship was stronger for independent self‐construal than the interdependent self‐construal. Path analysis showed that the effect of interdependent self‐construal seemed to be weaker in Japan than in England. Conclusion: Future studies need to explore the effects of cultural context and environmental experiences such as the role of parenting styles that account for the higher levels of anxiety in English compared with Japanese adolescents. Depression and Anxiety, 2011.

Effects of Safety Behaviour On the Maintenance of Anxiety and Negative Belief Social Anxiety Disorder

Background: Safety behaviour plays an important role in the maintenance of social anxiety disorder (SAD). SAD patients engage in various safety behaviours in social situations in order to decrease the risk of negative evaluations from others. Aims: The present study examined the effect of safety behaviour on the maintenance of anxiety and negative belief in SAD by using Structural Equation Modelling (SEM). Methods: Participants were a healthy group (442) and a SAD group (46) who met the SAD criteria for DSM-IV and who had high scores of SAD symptoms. In the assumed maintenance model, independence variables were safety and avoidance behaviour and dependence variables were anxiety and negative belief. Results: This result showed that the SAD group significantly has more high scores than the healthy group in all scales of anxiety, negative belief and avoidance behaviour, expect for safety behaviour. The result of the multiple-group procedure indicated that safety behaviour contributes more strongly to anxiety and negative belief in the SAD group than in the healthy group. Conclusions: It is speculated that the SAD group have a stronger link between safety behaviour and negative belief than the healthy group, whereas frequency of the use of safety behaviour is equivalent between two groups. These results support the findings of previous studies.

A Japanese form of social anxiety (taijin kyofusho): Frequency and correlates in two generations of the same family

Background: One specific type of social anxiety, occurring primarily in Japanese culture, is called taijin kyofusho. Taijin kyofusho is characterized by an intense fear that one’s body parts or functions displease, embarrass or are offensive to others. Aim: The main aim of the present study was to compare the frequency and correlates of taijin kyofusho symptoms (TKS) in Japanese adolescents and their parents. Method: The sample included 351 adolescents, aged 12 to 17 years, and one of their parents/guardians. These adolescents were recruited from secondary schools in Miyazaki, Japan. All participants completed a set of questionnaires that were used to measure TKS, DSM-IV anxiety disorder symptoms, general difficulties and positive attributes, self-construals and social support. Results: Adolescents reported significantly more TKS than their parent/guardians. In each generational sample high TKS was significantly associated with high levels of anxiety symptoms, the strongest correlation being with social phobia. The pattern of the relationship between self-construal and TKS differed across the two generations. Among adolescents, independent self-construal was associated with lower TKS, whereas among parents, interdependent self-construal was associated with lower evaluative concerns from others. Conclusion: The present study illustrates the importance of the diverse roles that self-construals play in TKS across different generations of the same family constellation in contemporary Japanese culture.

Preliminary Assessment of the Behavioral Activation Model in Japanese Undergraduate Students

Many studies have reported that behavioral activation is an effective intervention for depression. The behavioral activation model is based on several formulations. For example, depressive mood leads to avoidant behaviors, avoidance negatively affects social contacts, decreased socialization lessens opportunities for positive reinforcement, and a decrease in positive reinforcement results in more depressive mood. The purpose of this study was to examine relationships among avoidant behavior, social contact, frequency of positive reinforcement, and depressive mood by using structural equation modeling to assess support for aspects of this behavioral activation model. Participants were 630 Japanese undergraduate students and vocational school students. Results provided preliminary support for the model. Treating both avoidance and activating behavior might contribute to decreased impairment.