Valgeir Thorvaldsson

Overweight in midlife and risk of dementia: a 40-year follow-up study

Objective:This study examines whether overweight in midlife increases dementia risk later in life.Methods:In 1963 body mass index was assessed in 1152 participants of The Swedish Twin Registry, at the age of 45–65 years. These participants were later screened for dementia in a prospective study with up to 40 years follow-up. A total of 312 participants were diagnosed with dementia.Results:Logistic regression analyses adjusted for demographic factors, smoking and alcohol habits, indicated that men and women categorized as overweight in their midlife had an elevated risk of dementia (OR=1.59; 95% CI: 1.21–2.07, P=0.002), Alzheimers disease (OR=1.71; 95% CI: 1.24–2.35, P=0.003), and vascular dementia (OR=1.55; 95% CI: 0.98–2.47, P=0.059). Further adjustments for diabetes and vascular diseases did not substantially affect the associations, except for vascular dementia (OR=1.36; 95% CI: 0.82–2.56, P=0.116), reflecting the significance of diabetes and vascular diseases in the etiology of vascular dementia. There was no significant interaction between overweight and APOE ɛ4 status, indicating that having both risk factors does not have a multiplicative effect with regard to dementia risk.Conclusions:This study gives further support to the notion that overweight in midlife increases later risk of dementia. The risk is increased for both Alzheimers disease and vascular dementia, and follows the same pattern for men and women.

Coordinated Analysis of Age, Sex, and Education Effects on Change in MMSE Scores

OBJECTIVES We describe and compare the expected performance trajectories of older adults on the Mini-Mental Status Examination (MMSE) across six independent studies from four countries in the context of a collaborative network of longitudinal studies of aging. A coordinated analysis approach is used to compare patterns of change conditional on sample composition differences related to age, sex, and education. Such coordination accelerates evaluation of particular hypotheses. In particular, we focus on the effect of educational attainment on cognitive decline. METHOD Regular and Tobit mixed models were fit to MMSE scores from each study separately. The effects of age, sex, and education were examined based on more than one centering point. RESULTS Findings were relatively consistent across studies. On average, MMSE scores were lower for older individuals and declined over time. Education predicted MMSE score, but, with two exceptions, was not associated with decline in MMSE over time. CONCLUSION A straightforward association between educational attainment and rate of cognitive decline was not supported. Thoughtful consideration is needed when synthesizing evidence across studies, as methodologies adopted and sample characteristics, such as educational attainment, invariably differ.

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.

Personality and personal control make a difference for life satisfaction in the oldest-old: findings in a longitudinal population-based study of individuals 80 and older

This study investigates life satisfaction in relation to impending death among the oldest-old using overall disease load, self-rated health, and personality as interacting covariates of level and change. We used data from a sample of 370 healthy individuals who completed the Life Satisfaction Index-Z at four measurement occasions during a 6-year period in the Swedish OCTO-Twin study of individuals aged 80 and older. Growth curve analyses showed a linear decrease in life satisfaction as individuals approached death. The decrease was not related to level or change in self-rated health and disease load. High disease load was, however, related to lower levels of life satisfaction, but, this association was moderated by locus of control, such that those with high disease load and high locus of control did not show lower life satisfaction. Poor self-rated health was also associated with lower life satisfaction, but, this association was moderated by neuroticism, such that those with poor-rated health and low neuroticism did not show lower live satisfaction. Personality factors such as locus of control and neuroticism can influence the association between health and life satisfaction. The findings suggest further investigations of the role of personality characteristics in late life satisfaction and whether interventions aimed to increase personal control can improve life satisfaction in old age.

Aging and Late-Life Terminal Decline in Perceptual Speed

Individual changes in perceptual speed were modeled as a conditional function of age and time-to-death. Alternative time-structured models were evaluated in a Swedish population-based, age-homogeneous sample (Gothenburg H70; N = 764) of individuals assessed at ages 70, 75, 79, 85, 88, 90, 92, 95, 97, and 99. Modeling time as proximity to death accounted better for the heterogeneity of individual changes than an age-based time structure. Time-to-death was a significant predictor of individual differences in rates of change in the age-based model but age did not significantly predict individual differences in rates of change in the model structured by proximity to death. In both the age-based and death-based time-structured models, accelerated changes prior to time of death were observed and provide support for the terminal-decline hypothesis. Identification of health-related factors and other sources of causal heterogeneity of aging-related change can make productive use of alternative time specifications ...

Onset and rate of cognitive change before dementia diagnosis: findings from two Swedish population-based longitudinal studies.

We used data from two population-based longitudinal studies to estimate time of onset and rate of accelerated decline across cognitive domains before dementia diagnosis. The H70 includes an age-homogeneous sample (127 cases and 255 non-cases) initially assessed at age 70 with 12 follow-ups over 30 years. The Kungsholmen Project (KP) includes an age-heterogeneous sample (279 cases and 562 non-cases), with an average age of 82 years at initial assessment, and 4 follow-ups spanning 13 years. We fit mixed linear models to the data and determined placement of change points by a profile likelihood method. Results demonstrated onset of accelerated decline for fluid (speed, memory) versus crystallized (verbal, clock reading) abilities occurring approximately 10 and 5 years before diagnosis, respectively. Although decline before change points was greater for fluid abilities, acceleration was more pronounced for crystallized abilities after the change points. This suggests that onset and rate of acceleration vary systematically along the fluid-crystallized ability continuum. There is early onset in fluid abilities, but these changes are difficult to detect due to substantial age-related decline. Onset occurred later and acceleration was greater in crystallized abilities, suggesting that those markers may provide more valid identification of cases in later stages of the prodromal phase.

Nonlinear blood pressure effects on cognition in old age: separating between-person and within-person associations.

Midlife hypertension is associated with increased risk of cognitive impairment in later life. The association between blood pressure (BP) in older ages and cognition is less clear. In this study we provide estimates of between-person and within-person associations of BP and cognition in a population-based sample (N = 382) followed from age 70 across 12 occasions over 30 years. Between-person associations refer to how individual differences in BP relates to individual differences in cognition. Within-person associations refer to how individual and time specific changes in BP relate to variation in cognition. Hierarchical linear models were fitted to data from three cognitive measurements (verbal ability, spatial ability, and perceptual speed) while accounting for demographic and health-related covariates. We found consistent nonlinear between-person associations between diastolic BP (DBP) and cognition, such that both low (<75 mmHg) and high (>95 mmHg) pressure were associated with poorer cognition. Within-person decreases in systolic BP (SBP) and DBP were associated with decreases in perceptual speed. Notably, between-person and within-person estimates did not reveal similar associations, suggesting the need to separate the two effects in the analysis of associations between BP and cognition in old age.

The pattern of cognitive symptoms predicts time to dementia onset

Few studies have examined whether cognitive symptom patterns differ by age and length of time before dementia onset. Our objective was to investigate whether different patterns of cognitive symptoms at ages 70, 75, and 79 years predict short‐term (≤5 years) and long‐term (>5 years) dementia onset.

Birth cohort differences in fluid cognition in old age : Comparisons of trends in levels and change trajectories over 30 years in three population-based samples

Later-born cohorts of older adults tend to outperform earlier born on fluid cognition (i.e., Flynn effect) when measured at the same chronological ages. We investigated cohort differences in level of performance and rate of change across three population-based samples born in 1901, 1906, and 1930, drawn from the Gerontological and Geriatric Population Studies in Gothenburg, Sweden (H70), and measured on tests of logical reasoning and spatial ability at ages 70, 75, and 79 years. Estimates from multiple-group latent growth curve models (LGCM) revealed, in line with previous studies, substantial differences in level of performance where later-born cohorts outperformed earlier born cohorts. Somewhat surprisingly, later-born cohorts showed, on average, a steeper decline than the earlier-born cohort. Gender and education only partially accounted for observed cohort trends. Men outperformed women in the 1906 and 1930 cohorts but no difference was found in the 1901 cohort. More years of education was associated with improved performance in all three cohorts. Our findings confirm the presence of birth cohort effects also in old age but indicate a faster rate of decline in later-born samples. Potential explanations for these findings are discussed.

Substantial effects of apolipoprotein E ε4 on memory decline in very old age: longitudinal findings from a population-based sample.

We examined associations between the apolipoprotein E (APOE) ε4 allele and levels of performance and rates of change in cognition in late life taking incident dementia into account. The sample consisted of 482 nondemented individuals, aged 80 years and older at baseline, drawn from the OCTO twin study. A battery of 10 cognitive tests was administered at 5 occasions with measurements intervals of 2 years. We fitted hierarchical linear models with time specified as time to death and controlled for baseline age, sex, education, stroke, cardiovascular disease, hypertension, diabetes, and incident dementia. The ε4 allele was significantly associated with lower levels of performance or steeper rate of decline in all 7 memory tests. Largest effect sizes were found in tests of delayed recall and recognition memory. The effects of the APOE ε4 allele were, however, reduced to a nonsignificant level in all tests except 1 after accounting for incident dementia. The findings support the notion that the APOE ε4 allele is associated with substantial memory decline in very old age, but as expected, the effect is largely related to incident dementia.