Atrial fibrillation increases the risk of dementia amongst older adults even in the absence of stroke.

BACKGROUND: Atrial fibrillation increases risk of stroke, and thus risk of cognitive impairment and dementia. Emerging evidence suggests an association also in the absence of stroke. We aimed to examine the association between atrial fibrillation and incident dementia, with and without exclusion of individuals with stroke, and if sex and genetic factors modify the possible association. METHODS: In 2000-2001, a population-based sample of 70-year-olds (N = 561) underwent comprehensive somatic and neuropsychiatric examinations, as part of the Gothenburg H70 Birth Cohort Studies. Participants were followed up at age 75 and 79. Atrial fibrillation at baseline was identified through ECG, proxy-reports and the National Patient Register (NPR). Stroke at baseline and follow-up was identified through self-reports, proxy-reports and the NPR. Dementia at baseline and follow-up was diagnosed according to the DSM-III-R criteria based on neuropsychiatric examinations, proxy-reports and the NPR. RESULTS: Individuals with atrial fibrillation had an almost threefold increased risk of dementia during 12-year follow-up (HR 2.8; 95% CI 1.3-5.7; P = 0.004), and this risk remained after excluding individuals with stroke at baseline and follow-up. After stratification for sex, the association was only found amongst men (HR 4.6; 95% CI 1.9-11.2; P < 0.001, interaction sex*atrial fibrillation; P = 0.047) and noncarriers of the APOE ε4 allele (HR 4.2; 95% CI 1.8-9.7; P < 0.001, interaction APOE*atrial fibrillation; P = 0.128). Population attributable risk for dementia resulting from atrial fibrillation was 13%. CONCLUSION: The relevance for atrial fibrillation as an indicator of subclinical brain vascular risk needs to be further explored. In addition, patients with atrial fibrillation should be screened for cognitive symptoms.

Dementias.

This chapter will focus on the descriptive, analytic, and intervention-oriented epidemiology of dementia and its most frequent etiologic type due to Alzheimer's disease. The chapter opens with a brief presentation of the concept of dementia, followed by the presentation of dementia of the Alzheimer type (DAT), including natural history, clinical manifestation, neuropathology, medical prognosis, and management. Further, the chapter presents the prevalence and incidence of dementia, with special consideration of secular trends in prevalence and incidence of DAT, and prognosis of the socioeconomic impact of dementia. Thereafter the main risk factors for DAT are covered. The chapter also addresses the results of ongoing therapeutic and preventive intervention trials for DAT. Finally, the future challenges of the epidemiology of dementia with a focus on the impact of the new diagnostic criteria for neurocognitive disorders, as well as the development of biomarkers for DAT and other types of dementia, will be briefly discussed.

A population-based study on the influence of brain atrophy on 20-year survival after age 85.

BACKGROUND: Individuals aged 80 years and older is the fastest growing segment of the population worldwide. To understand the biology behind increasing longevity, it is important to examine factors related to survival in this age group. The relationship between brain atrophy and survival after age 85 remains unclear. METHODS: A population-based sample (n = 239) had head CT scans at age 85 and was then followed until death. Cortical atrophy and ventricular size were assessed. Statistical analyses included Cox proportional hazards models with time to death as the outcome and considering a large number of possible confounders, including baseline cognitive function, incident dementia, and somatic disorders. RESULTS: Mean survival time (±SD) was 5.0 ± 3.6 years (range 0.10-19.8 years). Decreased survival was associated with temporal, and frontal atrophy, sylvian fissure width and a number of ventricular measures after adjustment for potential confounders. In participants without dementia at baseline (n = 135), decreased survival was associated with temporal lobe atrophy and bifrontal ratio. In those with dementia (n = 104), decreased survival was associated with third ventricle width, cella media ratio, and ventricle-to-brain and ventricle-to-cranial ratio. CONCLUSIONS: Several indices of brain atrophy were related to decreased survival after age 85, regardless of dementia status. Brain atrophy is rarely mentioned as a significant indicator of survival in the elderly, independent of traditional predictors such as cardiovascular disease or cancer. The biology behind the influence of brain atrophy on survival needs to be further scrutinized.

Secular changes in cognitive predictors of dementia and mortality in 70-year-olds.

BACKGROUND: Successive elderly birth cohorts improved in cognitive performance during the 20th century. It is not clear whether this influences cognitive predictors of dementia and mortality. OBJECTIVE: In 2 longitudinal population studies, representing 2 cohorts of 70-year-olds examined 30 years apart, we investigated the relation between baseline cognitive function and 5-year occurrence of dementia and mortality. METHODS: Two representative cohorts of 70-year-olds initially free from dementia born in 1901-1902 (cohort 1901-1902: n = 381) and 1930 (cohort 1930: n = 551) from Gothenburg, Sweden, were examined in 1971-1972 and 2000-2001 and after 5 years for the outcome of dementia and death. Recent memory was evaluated during psychiatric examinations, and nonmemory domains using psychometric tests. RESULTS: At age 70, cohort 1930 performed better on psychometric tests, and had fewer recent memory problems compared to cohort 1901-1902. During 5-year follow-up, 5.0% in cohort 1901-1902 and 4.4% in cohort 1930 (p = 0.742) developed dementia, and 15.7% in cohort 1901-1902 and 4.4% in cohort 1930 died (p < 0.001). Recent memory was associated with incident dementia in both cohorts. Low scores in nonmemory tests were associated with incident dementia in cohort 1901-1902, but not in cohort 1930. Recent memory problems and lower scores in nonmemory tests were associated with 5-year mortality in cohort 1901-1902, but not in cohort 1930. CONCLUSIONS: Secular changes in cognitive performance may influence cognitive predictors of dementia and mortality, despite similar incidence of dementia. The findings should be taken cautiously due to differences between cohorts in refusal rates, quality of education, and dementia recognition in medical records.

Onset of terminal decline in cognitive abilities in individuals without dementia.

OBJECTIVE: To identify time of onset and rate of mortality-related change (terminal decline) in cognitive abilities in later life. METHOD: The sample consisted of 288 individuals without dementia (born 1901-1902) drawn from the population of Göteborg, Sweden. Participants were followed from age 70 until death, with up to 12 measurement occasions on three cognitive abilities. Change-point analysis was performed using an automated piecewise linear mixed modeling approach to identify the inflection point indicating accelerated within-person change related to mortality. A profile likelihood method was used to identify the change point that best fit the data for each of three cognitive abilities. RESULTS: Onset of terminal decline was identified 6.6 years prior to death for verbal ability, 7.8 years for spatial ability, and 14.8 years for perceptual speed. CONCLUSIONS: There is substantial acceleration in cognitive decline many years prior to death among individuals without dementia. Time of onset and rate of terminal decline vary considerably across cognitive abilities.

Prodromal cognitive signs of dementia in 85-year-olds using four sources of information.

OBJECTIVE: To evaluate the utility of assessing four cognitive domains obtained from four information sources to identify individuals at risk for developing dementia, Alzheimer disease (AD), and vascular dementia (VaD). METHODS: A representative population sample of nondemented 85-year-olds (n = 313) from Gothenburg, Sweden, was examined regarding memory, language, and visuospatial and executive functions, using self- and key informant reports and neuropsychiatric and psychometric examinations. The sample was followed 3 years for incident dementia, AD, or possible VaD. RESULTS: All cases of dementia, AD, and VaD were preceded by low performance in most domains irrespective of information source. Isolated low memory performance or low cognitive performance with unimpaired memory did not predict dementia. Positive predictive values increased with number of domains affected. Self- and key informant reports were less useful for predicting dementia than neuropsychiatric and psychometric examinations. The best positive predictive value (88%) was for low cognitive performance in all domains using neuropsychiatric and psychometric examinations; however, sensitivity was only 18%. CONCLUSIONS: Although memory impairment was necessary to predict dementia, it was not sufficient. Other cognitive domains needed to be affected. Relying on self-reports or key informants for early detection of dementia excluded a large group at risk. In addition, vascular dementia appeared to have a prodromal stage.