Data from: Body mass index, diet, physical inactivity and the incidence of dementia in one million UK women

Floud, Sarah, University of Oxford

Simpson, Rachel F, University of Oxford

Balkwill, Angela, University of Oxford

Brown, Anna, University of Oxford

Goodill, Adrian, University of Oxford

Gallacher, John E., University of Oxford

Sudlow, Cathie L.M., University of Oxford

Harris, Phillip, University of Oxford

Hofman, Albert, University of Oxford

Parish, Sarah, University of Oxford

Reeves, Gillian K, University of Oxford

Green, Jane, University of Oxford

Peto, Richard, University of Oxford

Beral, Valerie, University of Oxford

sarah.floud@ndph.ox.ac.uk

Published Jan 13, 2020 on Dryad. https://doi.org/10.5061/dryad.3s755j8

Cite this dataset

Floud, Sarah et al. (2020). Data from: Body mass index, diet, physical inactivity and the incidence of dementia in one million UK women [Dataset]. Dryad. https://doi.org/10.5061/dryad.3s755j8

Abstract

Objective: To help determine whether mid-life obesity is a cause of dementia, and whether low BMI, low caloric intake and physical inactivity are causes or merely consequences of the gradual onset of dementia, we recorded these factors early in a large 20-year prospective study and related them to dementia detection rates separately during follow-up periods 0-4, 5-9, 10-14 and 15+ years. Methods: 1,136,846 UK women, mean age 56 (SD=5) years, were recruited in 1996-2001 and asked about height, weight, caloric intake and inactivity. They were followed until 2017 by electronic linkage to National Health Service records, detecting hospital admissions with mention of dementia. Cox regression yielded adjusted rate ratios (RRs) for first dementia detection during particular follow-up periods. Results: 15 years after the baseline survey only 1% were lost to follow-up and 89% remained alive with no detected dementia, of whom 18,695 had dementia detected later, at mean age 77 (SD=4) years. Dementia detection during years 15+ was associated with baseline obesity (BMI 30+ versus 20-24 kg/m2: RR=1.21, 95% CI 1.16-1.26; p<0.0001), but not clearly with low BMI, low caloric intake or inactivity at baseline. The latter three factors were associated with dementia rates during the first decade, but these associations weakened substantially over time, approaching null after 15 years. Conclusions: Mid-life obesity may well be a cause of dementia. In contrast, behavioural changes due to preclinical disease could largely or wholly account for associations of low BMI, low caloric intake and inactivity with dementia detection during the first decade.

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Supplementary files

Contents of supplementary files: Additional methods 1 Flow chart of inclusions and exclusions Additional methods 2 Assessment of diet Additional methods 3 Comparison of dementia rates in primary care and in hospital, for Million Women Study participants Table 2 Characteristics at baseline of all women and of women who were still alive after 15 years of follow-up Table 3 Dementia detection rate ratios for dementia types in relation to obesity vs desirable BMI with 15+ years of follow-up: effect of adjustment by various factors Figure 7 Dementia detection rate ratio by period of follow-up for various dietary intakes Figure 8 Dementia detection rate ratio by period of follow-up for various factors in women with good or excellent self-rated health at baseline Figure 9 Dementia detection rate ratio after 15+ years of follow-up, by hospital-specified type of dementia: censoring women with stroke at the date of the stroke Figure 10 Dementia detection rate ratio by period of follow-up for various factors, including both hospital admissions and deaths with dementia

supplementary files.zip