Hispanics

The Religious Orders Study enrolls Catholic nuns, priests and brothers, from more than 40 groups across the United States (Figure 1). Participants are without known dementia and agree to annual clinical evaluation and brain donation (some in the Chicago area also agree to donate, spinal cord, nerve, and muscle). Each subject signs a consent form and an Anatomical Gift Act. The study was approved by the Institutional Review Board of Rush University Medical Center.
The study primarily recruits persons living communally, including employed (e.g., Teaching Orders) and retired (e.g., Missionary Orders) persons. The study includes three predominantly African American communities in New York, Baltimore, and New Orleans, and enrolls Hispanic sisters primarily from communities in and around San Antonio. All data collection forms have been translated into Spanish. Working with religious communities offers a number of advantages. First, they are altruistic and have a history of participating in research projects from which they may derive little to no personal benefit. Second, they live communally and loss of contact with participants is rare, facilitating the high follow-up and autopsy rates required to ensure internal study validity. Third, their wishes for organ donation are likely to be honored by the Superior and biological family members are unlikely to interfere with the participants’ written preference. Finally, the participants have similar education, socioeconomic and life experiences for most of their adult lives. This allows for tighter control of these potentially confounding variables in analyses of incident AD and cognitive decline.
The study design (Figure 2) supports the following analyses in a single dataset: 1) the association of neurobiologic indices with AD, MCI, and cognition proximate to death and over multiple years prior to death; 2) the association of risk factors for incident AD, incident MCI, and cognitive decline; and 3) the modeling of neurobiologic pathways linking risk factors to clinical phenotypes. The collection of parkinsonian signs and other measures of motor function allow for similar analyses to be conducted with motor function and decline, and disability.

Gait speed was calculated for each participant using distance in meters and time in seconds. All studies used instructions to walk at usual pace and from a standing start. The walk distance varied from 8 ft to 6 m. For 8 ft, we converted to 4-m gait speed by formula.24 (link) For 6 m, we created a conversion formula (4-m speed=−0.0341 + (6-mspeed)×0.9816 withR²=0.93, based on a cohort of 61 individuals with concurrent 4- and 6-m walks). For 15 feet (4.57 m),23 (link) speed was simply meters divided by time. Where available, data on fast gait speed (walk as fast as comfortably able25 (link)) and the Short Physical Performance Battery were obtained.26 (link) Survival for each individual used study monitoring methods, including the National Death Index and individual study follow-up. Time from gait speed baseline to death was calculated in days. Five-year survival status was confirmed for more than 99% of participants.
Additional variables include sex, age, race/ethnicity (white, black, Hispanic, other, defined by participant), height(centimeters), weight(kilograms), body mass index (BMI), calculated as weight in kilograms divided by height in meters squared (<25, 25–30, and >30), smoking (never, past, current), use of mobility aids (none, cane, walker), systolic blood pressure, self-reports of health (excellent or very good vs good, fair, or poor), hospitalization in the past year (yes/no), and physician-diagnosed medical conditions (cancer, arthritis, diabetes, and heart disease, all yes/no). Measures of self-reported functional status were not collected in all studies and varied in content and form. We created a dichotomous variable reflecting dependence in basic activities of daily living (ADLs) based on report of being unable or needing help from another person to perform any basic activity, including eating, toileting, hygiene, transfer, bathing, and dressing. For individuals independent in ADLs, we created a dichotomous variable reflecting difficulty in instrumental ADLs based on report of difficulty or dependence with shopping, meal preparation, or heavy housework due to a health or physical problem. Participants were then classified into 1 of 3 groups; dependent in ADLs, difficulty with instrumental ADLs, or independent. Physical activity data were collected in 6 studies, but time frames and items varied widely. Two studies used the Physical Activity Scale for the Elderly (PASE).27 (link) We dichotomized the PASEs core at 100.28 (link) We created operational definitions of other covariates that were reasonably consistent across studies. Covariates were identical for height, weight, BMI, and systolic blood pressure. Hospitalization within the prior year was determined largely by self-report, and chronic conditions were by self-report of physician diagnosis, with heart disease encompassing angina, coronary artery disease, heart attack, and heart failure.