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This study tested phenotypic and biometric associations between physical and cognitive catch‐up growth in a community sample of twins (n = 1285, 51.8% female, 89.3% White). Height and weight were measured at up to 17 time points between birth and 15 years, and cognitive ability was assessed at up to 16 time points between 3 months and 15 years. Weight and length at birth were positively associated with cognitive abilities in infancy and adolescence (r's =.16–.51). More rapid weight catch‐up growth was associated with slower, steadier cognitive catch‐up growth. Shared and nonshared environmental factors accounted for positive associations between physical size at birth and cognitive outcomes. Findings highlight the role of prenatal environmental experiences in physical and cognitive co‐development. [ABSTRACT FROM AUTHOR]

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]

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., (© 2023 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)