Objectives MIDUS is a national study of health and aging among individuals aged 25 to 74 at baseline(1995/96). Longitudinal survey assessments (2004/05), were followed by biological assessments on a subsample aged 35–85. To facilitate public use, we describe the protocol, measures, and sample. Methods Respondents traveled to clinics for a two-day data collection protocol that included fasting blood specimens, 12-hour urine specimen, medical history, physical exam, bone densitometry, a laboratory challenge (heart rate variability, blood pressure, respiration, salivary cortisol). Results Response rates for the biological protocol (N = 1,255) were 39.3%, or 43.1% (adjusting for those who could not be located or contacted). Reasons for non-participation were travel, family obligations, and being too busy. Respondents were comparable to the recruitment pool on most demographic characteristics and health assessments. Discussion Strengths of the protocol vis-à-vis other similar studies include opportunities to link biological factors with diverse content from other MIDUS projects.

The hypothesis that the S allele of the 5-HTTLPR serotonin transporter promoter region is associated with increased risk of depression, but only in individuals exposed to stressful situations, has generated much interest, research, and controversy since first proposed in 2003. Multiple meta-analyses combining results from heterogeneous analyses have not settled the issue. To determine the magnitude of the interaction and the conditions under which it might be observed, we performed new analyses on 31 datasets containing 38 802 European-ancestry subjects genotyped for 5-HTTLPR and assessed for depression and childhood maltreatment or other stressful life events, and meta-analyzed the results. Analyses targeted two stressors (narrow, broad) and two depression outcomes (current, lifetime). All groups that published on this topic prior to the initiation of our study and met the assessment and sample size criteria were invited to participate. Additional groups, identified by consortium members or self-identified in response to our protocol (published prior to the start of analysis1) with qualifying unpublished data were also invited to participate. A uniform data analysis script implementing the protocol was executed by each of the consortium members. Our findings do not support the interaction hypothesis. We found no subgroups or variable definitions for which an interaction between stress and 5-HTTLPR genotype was statistically significant. In contrast, our findings for the main effects of life stressors (strong risk factor) and 5-HTTLPR genotype (no impact on risk) are strikingly consistent across our contributing studies, the original study reporting the interaction, and subsequent meta-analyses. Our conclusion is that if an interaction exists in which the S allele of 5-HTTLPR increases risk of depression only in stressed individuals, then it is not broadly generalizable, but must be of modest effect size and only observable in limited situations.

Despite a social structure where elderly persons often live with their children and social interaction is likely to be more family-centered than in western countries, data from Taiwan suggest that participation in social activities outside the family may have a bigger impact on cognitive function than social contacts with family or non-relatives.

A simple subjective assessment of one's ranking on the social hierarchy was associated with self-rated health and physical functional status in an older ethnic Chinese population. The associations were independent of the effects of traditional objective measures of SES, such as education, income, and occupation.