Dementia remains the major predictor of death among octogenarians. A study of two population cohorts of 85-year-olds examined 22 years apart.

Dementia is the major predictor of death in old age. The aim of this paper was to determine whether 8-year mortality among 85-year olds with and without dementia, and if the contribution of dementia to mortality relative to other common diseases has changed. We used two population-based cohorts of 85-year-olds (N = 1065), born in 1901-02 and 1923-24, which were examined with identical methods in 1986-87 and 2008-2010 and followed for 8-year mortality according to data from the Swedish Tax Agency. Dementia was diagnosed according to DSM-III-R. Other diseases were diagnosed based on self-reports, close informant interviews, somatic examinations, and the Swedish National In-patient Register. Compared to cohort 1901-02, cohort 1923-24 had a lower 8-year mortality both among those with (HR 0.7; 95% CI 0.5-0.99) and without dementia (HR 0.7; 95% CI 0.5-0.9). Dementia was associated with increased mortality in both cohorts (cohort 1901-02, HR 2.6; 95% CI 2.0-3.2, cohort 1923-24, HR 2.8; 95% CI 2.3-3.5), and remained the major predictor of death, with a population attributable risk of 31.7% in 1986-87 and 27.7% in 2008-10. Dementia remained the most important predictor of death in both cohorts. The relative risk for mortality with dementia did not change between cohorts, despite a decreased mortality rate in the population.

Amyloid ß42 and Total Tau Levels in Cerebrospinal Fluid Associate with Survival in an 85-Year-Old Population-Based Cohort Followed until Death.

BACKGROUND: Dementia of Alzheimer's type (AD) is related to decreased survival. It is not clear whether also biological markers of AD are related to mortality. Low levels of amyloid beta-42 (Aß42) and high levels of total tau (T-tau) protein in cerebrospinal fluid (CSF) are established biomarkers for AD. OBJECTIVE: Our aim was to investigate whether levels of Aß42 and T-tau are associated with survival among octogenarians independently of dementia status. METHODS: Sixty-five 85-year-olds underwent lumbar puncture and were followed with repeated neuropsychiatric examinations until death. RESULTS: Lower CSF Aß42 (p = 0.010) and higher CSF T-tau (p = 0.005) at the age of 85 were associated with lower survival independently of dementia status at baseline and follow-up. Low CSF Aß42 and high CSF T-tau were also related to baseline dementia at the age of 85 years, and lower CSF Aß42 with increased dementia incidence during the first 3 years of follow-up. CONCLUSIONS: Biological markers of AD are associated with mortality in octogenarians. The reason for this needs further study. Our findings highlight the importance to consider the competing risk of death when evaluating biological markers of AD in the very old.

The Gothenburg H70 Birth cohort study 2014-16: design, methods and study population.

To improve health care for older persons, we need to learn more about ageing, e.g. identify protective factors and early markers for diseases. The Gothenburg H70 Birth Cohort Studies (the H70 studies) are multidisciplinary epidemiological studies examining representative birth cohorts of older populations in Gothenburg, Sweden. So far, six birth cohorts of 70-year-olds have been examined over time, and examinations have been virtually identical between studies. This paper describes the study procedures for the baseline examination of the Birth cohort 1944, conducted in 2014-16. In this study, all men and women born 1944 on specific dates, and registered as residents in Gothenburg, were eligible for participation (n = 1839). A total of 1203 (response rate 72.2%; 559 men and 644 women; mean age 70.5 years) agreed to participate in the study. The study comprised sampling of blood and cerebrospinal fluid, psychiatric, cognitive, and physical health examinations, examinations of genetics and family history, use of medications, social factors, functional ability and disability, physical fitness and activity, body composition, lung function, audiological and ophthalmological examinations, diet, brain imaging, as well as a close informant interview, and qualitative studies. As in previous examinations, data collection serves as a basis for future longitudinal follow-up examinations. The research gained from the H70 studies has clinical relevance in relation to prevention, early diagnosis, clinical course, experience of illness, understanding pathogenesis and prognosis. Results will increase our understanding of ageing and inform service development, which may lead to enhanced quality of care for older persons.

Attrition in the Gothenburg H70 birth cohort studies, an 18-year follow-up of the 1930 cohort.

Background: Longitudinal studies are essential to understand the ageing process, and risk factors and consequences for disorders, but attrition may cause selection bias and impact generalizability. We describe the 1930 cohort of the Gothenburg H70 Birth Cohort Studies, followed from age 70 to 88, and compare baseline characteristics for those who continue participation with those who die, refuse, and drop out for any reason during follow-up. Methods: A population-based sample born 1930 was examined with comprehensive assessments at age 70 (N = 524). The sample was followed up and extended to increase sample size at age 75 (N = 767). Subsequent follow-ups were conducted at ages 79, 85, and 88. Logistic regression was used to analyze baseline characteristics in relation to participation status at follow-up. Results: Refusal to participate in subsequent examinations was related to lower educational level, higher blood pressure, and lower scores on cognitive tests. Both attrition due to death and total attrition were associated with male sex, lower educational level, smoking, ADL dependency, several diseases, poorer lung function, slower gait speed, lower scores on cognitive tests, depressive symptoms, and a larger number of medications. Attrition due to death was also associated with not having a partner. Conclusions: It is important to consider different types of attrition when interpreting results from longitudinal studies, as representativeness and results may be differently affected by different types of attrition. Besides reducing barriers to participation, methods such as imputation and weighted analyses can be used to handle selection bias.

Representativeness in population-based studies of older adults: five waves of cross-sectional examinations in the Gothenburg H70 Birth Cohort Study.

OBJECTIVES: To describe representativeness in the Gothenburg H70 1930 Birth Cohort Study. DESIGN: Repeated cross-sectional examinations of a population-based study. SETTING: Gothenburg, Sweden. PARTICIPANTS: All residents of Gothenburg, Sweden, born on specific birth dates in 1930 were invited to a comprehensive health examination at ages 70, 75, 79, 85 and 88. The number of participants at each examination was 524 at age 70, 767 at age 75, 580 at age 79, 416 at age 85, and 258 at age 88. PRIMARY OUTCOME MEASURES: We compared register data on sociodemographic characteristics and hospital discharge diagnoses between participants and (1) refusals, (2) all same-aged individuals in Gothenburg and (3) all same-aged individuals in Sweden. We also compared mortality rates between participants and refusals. RESULTS: Refusal rate increased with age. At two or more examination waves, participants compared with refusals had higher educational level, more often had osteoarthritis, had lower mortality rates, had lower prevalence of neuropsychiatric, alcohol-related and cardiovascular disorders, and were more often married. At two examination waves, participants compared with same-aged individuals in Gothenburg had higher education and were more often born in Sweden. At two examination waves or more, participants compared with same-aged individuals in Sweden had higher education, had higher average income, less often had ischaemic heart disease, were less often born in Sweden and were more often divorced. CONCLUSIONS: Participants were more similar to the target population in Gothenburg than to refusals and same-aged individuals in Sweden. Our study shows the importance of having different comparison groups when assessing representativeness of population studies, which is important in evaluating generalisability of results. The study also contributes unique and up-to-date knowledge about participation bias in these high age groups.

Time trends in the relation between blood pressure and dementia in 85-year-olds.

OBJECTIVES: Blood pressure has decreased in the general population. We aimed to examine whether this is true also among the very old, and among persons with and without dementia. Further, we aimed to investigate how common undetected and untreated hypertension is in the very old, both among people with and without dementia. METHOD: Blood pressure was measured in representative population samples of 85-year-olds living in Gothenburg, Sweden, examined 1986-1987 (n = 484) and 2008-2010 (n = 571). Dementia was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, edition 3 revised, by the same medical doctor at both examinations. RESULTS: Both systolic and diastolic blood pressure were lower in 85-year-olds examined 2008-2010 than in those examined 1986-1987, both among those with and without dementia. Participants with dementia had lower systolic blood pressure than those without dementia in both cohorts, and blood pressure levels related to dementia severity. Despite this, hypertension (≥140/90 mmHg) was found in almost half (46.5%) of those with dementia in 2008-2010. CONCLUSION: Our findings show that time-trends of lower blood pressure in western populations also applies to the very old, and that individuals with dementia continue to have lower blood pressure compared to the rest of the population. The latter finding suggests that the pathophysiological processes in dementia affect blood pressure regulating regions in the brain independent of time trends. Still, hypertension is common in dementia and needs to be detected and treated.

A Longitudinal Study of the Mini-Mental State Examination in Late Nonagenarians and Its Relationship with Dementia, Mortality, and Education.

OBJECTIVES: To examine level of and change in cognitive status using the Mini-Mental State Examination (MMSE) in relation to dementia, mortality, education, and sex in late nonagenarians. DESIGN: Three-year longitudinal study with examinations at ages 97, 99, and 100. SETTING: Trained psychiatric research nurses examined participants at their place of living. PARTICIPANTS: A representative population-based sample of 97-year-old Swedes (N = 591; 107 men, 484 women) living in Gothenburg, Sweden. MEASUREMENTS: A Swedish version of the MMSE was used to measure cognitive status. Geriatric psychiatrists diagnosed dementia according to the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised. Mixed models were fitted to the data to model the longitudinal relationship between MMSE score and explanatory variables. RESULTS: Individuals with dementia between age 97 and 100 had lower mean MMSE scores than those without dementia. Those who died during the 3-year follow-up had lower MMSE scores than those who survived. MMSE scores at baseline did not differ between those without dementia and those who developed dementia during the 3-year follow-up. Participants with more education had higher MMSE scores, but there was no association between education and linear change. CONCLUSION: MMSE score is associated with dementia and subsequent mortality even in very old individuals, although the preclinical phase of dementia may be short in older age. Level of education is positively associated with MMSE score but not rate of decline in individuals approaching age 100.