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INTRODUCTION: Dementia predicts increased mortality. We used case‐control and co‐twin control models to investigate genetic and shared environmental influences on this association. METHODS: Case‐control design, including 987 twins with dementia and 2938 age‐ and sex‐matched controls in the Swedish Twin Registry. Co‐twin control design, including 90 monozygotic (MZ) and 288 dizygotic (DZ) twin pairs discordant for dementia. To test for genetic and environmental confounding, differences were examined in mortality risk between twins with dementia and their matched or co‐twin controls. RESULTS: Twins with dementia showed greater mortality risk than age‐ and sex‐matched controls (HR = 2.02 [1.86, 2.18]). Mortality risk is significantly elevated but attenuated substantially in discordant twin pairs, for example, comparing MZ twins with dementia to their co‐twin controls (HR = 1.48 [1.08, 2.04]). DISCUSSION: Findings suggest that genetic factors partially confound the association between dementia and mortality and provide an alternative hypothesis to increased mortality due to dementia itself. Highlights: We studied dementia and mortality in twin pairs discordant for dementia.People without dementia outlived people with dementia.Identical twins with dementia and their co‐twin controls had similar survival time.Findings suggest genotype may explain the link between dementia and mortality. [ABSTRACT FROM AUTHOR]

Latent variable models can create a latent dementia index (LDI) using cognitive and functional ability to approximate dementia likelihood. The LDI approach has been applied across diverse cohorts. It is unclear whether sex affects its measurement properties. We use Wave A (2001–2003) of the Aging, Demographics, and Memory Study (n = 856). Multiple group confirmatory factor analysis (CFA) was used to test measurement invariance (MI) using informant‐reported functional ability and cognitive performance tasks, which we group into verbal, nonverbal, and memory. Partial scalar invariance was found, allowing for testing sex differences in LDI means (MDiff = 0.38). The LDI correlated with consensus panel dementia diagnosis, Mini‐Mental State Examination (MMSE), and dementia risk factors (low education, advanced age, and apolipoprotein ε4 [APOE‐ε4] status) for men and women. The LDI validly captures dementia likelihood to permit estimation of sex differences. LDI sex differences indicate higher dementia likelihood in women, potentially due to social, environmental, and biological factors. [ABSTRACT FROM AUTHOR]

Although several studies have shown small longitudinal associations between baseline loneliness and subsequent dementia risk, studies rarely test whether change in loneliness predicts dementia risk. Furthermore, as both increase with advancing age, genetic and environmental selection processes may confound the putative causal association between loneliness and dementia risk. We used a sample of 2,476 individual twins from three longitudinal twin studies of aging in the Swedish Twin Registry to test the hypothesis that greater positive change in loneliness predicts greater dementia risk. We then used a sample of 1,632 pairs of twins to evaluate the hypothesis that effects of change in loneliness on dementia risk would remain after adjusting for effects of genetic and environmental variance. Phenotypic model results suggest that mild levels of baseline loneliness predict greater dementia risk. Contrary to our hypothesis, change in loneliness did not correlate with dementia risk, regardless of whether genetic and environmental selection confounds were taken into account. Worsening loneliness with age may not confer greater dementia risk. [ABSTRACT FROM AUTHOR]