Phase I & II of the Georgia Centenarian Study
We have been most fortunate to have funded three different phases of our research.
Phase 1 (1988-1992) was a cross-sectional study examining unique adaptational characteristics of community-dwelling and cognitively-intact centenarians, octogenarians, and sexagenarians in Georgia. This was a collaboration among The University of Georgia, Medical College of Georgia, and Iowa State University and funded by the National Institute of Mental Health (NIMH). Leonard W. Poon, Peter Martin, and Mary Ann Johnson were in co-principal investigators with collaborations with many colleagues, students, and staff across the three universities. In this study, we compared “expert survivors” (who are cognitively intact and community dwelling centenarians) with “master survivors” (who are octogenarians with similar cognitive and community dwelling characteristics) and sexagenarians.
Phase 2 (1992-1998) was a study to evaluate stability and changes of the three groups over time. This study was also funded by NIMH.
Phase 3 (2001-2007) is a program project designed to identify and isolate longevity genes, neuropathology, functional capacity, and adaptational characteristics of a population-based sample of centenarians and controls in 44 counties in Northern Georgia . This program project is a collaboration among The University of Georgia, Boston University , Duke University , Emory University , Iowa State University, Louisiana State University , Rosalind Franklin University of Medicine and Science, University of Kentucky and University of Michigan and is funded by the NIA
Selected Findings of the Georgia Centenarian Study
The following are selected key findings generated from 1988 to the present based on the data collected in Phases I and II of our study:(1) Health and Health Habits: Consistent with the findings from the Alameda County Study (Breslow & Breslow, 1993) and the Harvard College Alumni Study (Paffenbarger et al., 1994), the Georgia centenarians tended to practice health habits that were found to prolong life (Nickols-Richardson, Johnson, Poon, & Martin, 1996a; Johnson, Houston, Fischer, Poon, & Martin, 1995). That is, few smoked, were obese, or consumed excessive alcohol. They remained active throughout life and ate breakfast on a regular basis. Compared to cohorts in their 60s and 80s, centenarians tended to escape contracting chronic diseases during their lifetime.
(2) Dietary Habits: The intake of most nutrients were similar among 60-, 80-, and 100-year old community-dwelling groups with few exceptions (Fischer et al., 1995; Williams, Johnson, Poon, & Martin, 1995; Johnson, Brown, Poon, Martin, & Clayton, 1992). Centenarians consumed about 20 – 30% more carotenoids and vitamin A from foods. They also consumed breakfast more regularly and avoided weight loss diets and large fluctuations in body weight. Lastly, centenarians tended to consume more whole milk, less 2% milk and yogurt, and were less likely to avoid dietary cholesterol.
(3) Cognition and Intelligence: Comparing cognitively-intact centenarians with younger cohorts, centenarians showed poorer performances in most cognitive functions except for everyday problem-solving tasks (Holtsberg, Poon, Noble, & Martin, 1995; Poon et al., 1992). The magnitudes of age differences were smaller in crystallized intelligence than in fluid intelligence. Education was shown to have a profound positive effect that mitigated the level of performance differences between subjects, especially centenarians. It is interesting to note that the performances of centenarians who used their everyday experiences in problem-solving were found to be similar to the younger cohorts (Poon, et al., 1992). Cognition accounted for about 20% of the variance in IADL for all subjects. When functional and mental health, as well as social and economic resources, were included in the regression equation, the amount of IADL variance that could be predicted increased to 37%. These findings show that cognition, health, and resources are all important predictors of everyday functions.
(4) Personality and Coping Styles: Centenarians were more dominant, suspicious, practical, and relaxed than those in their 60s and 80s (Martin et al., 1992). Centenarians were less likely to use active behavioral coping but were more likely to use cognitive coping behaviors when compared to octogenarians (Martin et al., 1992). Centenarians were more likely to acknowledge problems than those in other age groups, and they were less likely to seek social support as a coping strategy for their problems (Martin, Poon, & Johnson, 1995).
(5) Support Systems: Community-dwelling centenarians reported having fewer potential visitors. They were less likely to talk on the telephone or have a spouse as a primary caregiver, but more likely to have their children as caregivers and to receive help with food and meal preparation from family and friends (Martin, Poon, Kim, & Johnson, 1996). However, they were just as likely as those in their 60s and 80s to have a confidante, to have daily visitors and to have someone help them if they were sick or disabled.
(6) Mental Health: Compared to younger community-dwelling cohorts, centenarians tended to report more somatic but not emotional symptoms. Although centenarians were found to have a higher level of depression, measured by the Geriatric Depression Scale (Yesavage, Brink, Rose, & et al., 1983), compared to younger cohorts, no clinical depression was found among the sample of community-dwelling centenarians. A comment on our findings on race difference is offered here. African-American centenarians had significantly higher levels of depression and poorer self-perceived health than their Caucasian counterparts. However, when education and income were taken into account, differences in self-perceived health were eliminated and differences in mental health decreased but remained significant (Kim, Bramlett, Wright, & Poon, 1998). This was found for all three age groups. This finding shows that concomitant measures such as education, socio-economic background, and mental health are very important and could influence survivorship and quality of life of the oldest old.
(7) Survival Analyses: These analyses were performed to ascertain which variables, if any, could predict length of survival after an individual attained the age of 100 (Poon et al, 2000). While regression and modeling analyses are currently being performed, our preliminary analyses have shown that five clusters of variables show promise. They are: gender, family longevity, income and social support, anthropometrics, and cognition.
(A) Women, on average, survived 1020 days after attaining 100 years. Men, on the other hand, survived an average of 781 days. The gender difference in survival in the first two years are not significantly different. However, the difference is significant after three years. The gender superiority for women is quite glaring among centenarians.
(B) Father’s age of death was found to exert a positive effect on the number of days of survival of centenarians. No effect was found for mother’s age of death.
(C) Three variables in social support seem to relate to length of survival among centenarians. They are: talking on the phone, having someone to help, and having a caregiver for the centenarians. These findings show that the availability of a support system is important to centenarians’ survival.
D) Three anthropometric measures were found to correlate positively to survival. They are: tricep skinfold (an index of body fat), body mass index, and waist to hip ratio. These findings suggest that once a person attains centenarian status, it is important to have sufficient nourishment to survive longer.
(E) Higher level of cognition after age 100 is positively related to longer length of survival. This was found in the positive correlation with problem solving, learning and memory, and the WAIS performance measures of picture arrangement and block design.
