Chisato Hayashi

The Osaka University Aged Twin Registry: Epigenetics and Identical Twins Discordant for Aging-Dependent Diseases

The Osaka University Aged Twin Registry (OUATR) is the largest adult twin registry in Japan. Since its establishment in 1974, the OUATR has conducted a number of studies with particular focus on the environmental contribution to physical-cognitive-mental aging, longevity and aging-dependent diseases in later adulthood. The registry consists of 12,000 pairs of Japanese twins born between 1900 and 1935. Two hundred and fifty pairs of twins have undergone comprehensive medical examination to date. Follow-up questionnaires have been mailed out on a regular basis, for the purpose of checking current vital statuses, health conditions, and so forth. The main objective of this longitudinal twin study is to contribute to the prevention of lifestyle-related diseases and the promotion of successful aging.

Association between subjective memory complaints and impaired higher-level functional capacity in people aged 60 years or older

OBJECTIVE We aimed to investigate the association between subjective memory complaints and higher-level functional capacity in either people with long-term care needs or those who require help to maintain functional capacity. METHODS We conducted a cross-sectional study among participants aged 60 years or older. We measured subjective memory complaints, higher-level functional capacity, and depressive symptoms, and then estimated odds ratios (ORs) by multiple logistic analysis. Subjective memory complaints were used as the predictor variable, higher-level functional capacity as the outcome variable, and age, depressive symptoms, medical history of diabetes and hypertension, frequency of going out, falling within a year, and body mass index as possible confounders. We assessed higher-level functional capacity using the Tokyo Metropolitan Institute of Gerontology (TMIG) index of competence score ≤5 as a cut-off (which is associated with higher one-year mortality rates). RESULTS We conducted analyses using 501 people aged 60 years or older. Among women, subjective memory complaints were associated with impaired higher-level functional capacity after adjustment for age and depressive symptoms (OR=3.36; 95% confidence interval [CI], 1.59-7.08). Among the men, subjective memory complaints were not significantly associated with impaired higher-level functional capacity after adjustment for age and depressive symptoms (OR=1.91; 95% CI, 0.88-4.12). CONCLUSIONS Subjective memory complaints among women can indicate impaired higher-level functional capacity and may suggest higher one-year mortality rates.

Factors Affecting the Appearance of 'Twin Language' : an Original Language Naturally Developing within Twin Pairs

ObjectivesThe appearance of ‘twin language’ has been highlighted as a reason for delayed language development in twins. ‘Twin language’ is a unique language understandable only within the pair, and not by their mother or others. The purpose of this study was to examine and clarify the factors affecting the appearance of ‘twin language’.MethodsA mailed questionnaires survey was conducted in 2733 mothers of twins. Of them, 1395 mothers returned the questionnaires. The core questionnaire asked for data on birth weight, age at first spoken word, whether the twins were as alike as two peas in a pod, household members and non-verbal play. Logistic regression analysis was used in this study.ResultsOut of the 1395 pairs included in this analysis, 598 pairs (42.9%) showed the appearance of a ‘twin language’. When the 598 pairs were divided by whether the twin pair was exactly alike or not, there were 112 opposite sex pairs, 105 not-alike male pairs, 106 not-alike female pairs, 129 exactly alike male pairs and 140 exactly alike female pairs. Namely, 38.4% of the opposite sex pairs, 40.4% of the not-alike male pairs, 39.3% of the not-alike female pairs, 47.6% of the exactly alike male pairs and 48.4% in the exactly alike female pairs had a twin language. By multivariate logistic regression analysis controlling for twins’ age, it was found that ‘twin language’ was significantly more frequent in exactly alike twin pairs, pairs with non-verbal play, and pairs with fewer older siblings.ConclusionsThese findings suggest that three factors (whether the twin pair is exactly alike or not, older siblings, non-verbal play) affect the appearance of ‘twin language’.

Associations between Depressive State and Impaired Higher-Level Functional Capacity in the Elderly with Long-Term Care Requirements.

Depressive state has been reported to be significantly associated with higher-level functional capacity among community-dwelling elderly. However, few studies have investigated the associations among people with long-term care requirements. We aimed to investigate the associations between depressive state and higher-level functional capacity and obtain marginal odds ratios using propensity score analyses in people with long-term care requirements. We conducted a cross-sectional study based on participants aged ≥65 years (n = 545) who were community dwelling and used outpatient care services for long-term preventive care. We measured higher-level functional capacity, depressive state, and possible confounders. Then, we estimated the marginal odds ratios (i.e., the change in odds of impaired higher-level functional capacity if all versus no participants were exposed to depressive state) by logistic models using generalized linear models with the inverse probability of treatment weighting (IPTW) for propensity score and design-based standard errors. Depressive state was used as the exposure variable and higher-level functional capacity as the outcome variable. The all absolute standardized differences after the IPTW using the propensity scores were <10% which indicated negligible differences in the mean or prevalence of the covariates between non-depressive state and depressive state. The marginal odds ratios were estimated by the logistic models with IPTW using the propensity scores. The marginal odds ratios were 2.17 (95%CI: 1.13–4.19) for men and 2.57 (95%CI: 1.26–5.26) for women. Prevention of depressive state may contribute to not only depressive state but also higher-level functional capacity.

The Japanese Study of Adult Twins Reared Apart and Growing Old Separately.

More than 100 pairs of adult twins, reared apart and growing old separately, have participated in the Japanese Study of Adult Twins Reared Apart and Growing Old Separately since it began in 1974. The subjects are 161 pairs of adult twins born between 1910 and 1945 in Japan. The main focus of this study is to investigate the influences of environmental factors and life history on life satisfaction and psychological well-being in later adulthood. A mail survey has been conducted on these twins each year since 1974. To date, the Wechsler Adult Intelligent Scale, Maudsley Personality Inventory, Newgarten Life Satisfaction Index, comprehensive medical examinations and personal interviews have been conducted for 12 twin pairs residing in various areas of Japan.

Linguistic Features of Japanese Twins at 3 or 4 Years of Age Evaluated by Illinois Test of Psycholinguistic Abilities

In general, twins have delayed language development early in childhood compared with singletons. The purpose of this study was to clarify the overall linguistic features of twins. A Japanese version of the Illinois Test of Psycholinguistic Abilities (ITPA) was administered in 24 twin pairs (aged 3 to 4 years) at their own homes. The overall language abilities of the twins were in the normal range (based on ITPA normative data: mean scale score 36.0 +/- 6.0 points), and for the ITPA subtests only, Auditory Reception fell within the range of language disorder (mean scale score 24.9 +/- 5.1 points). The findings suggest that in 3- to 4-year-old Japanese twins, overall language abilities are not delayed. However, there may be specific difficulties with auditory reception skills.