Elizabeth E. Devore

Dietary antioxidants and long-term risk of dementia

BACKGROUND The Rotterdam Study previously found that higher dietary intakes of vitamins E and C related to lower risk of dementia and Alzheimer disease (AD) over 6 years of follow-up. OBJECTIVE To study consumption of major dietary antioxidants relative to long-term risk of dementia. DESIGN Population-based prospective cohort study. SETTING The Rotterdam Study in the Netherlands. PARTICIPANTS A total of 5395 participants, 55 years and older, who were free of dementia and provided dietary information at study baseline. MAIN OUTCOME MEASURES Incidence of dementia and AD, based on internationally accepted criteria, relative to dietary intake of vitamin E, vitamin C, beta carotene, and flavonoids. RESULTS During a mean follow-up period of 9.6 years, dementia developed in 465 participants, of whom 365 were diagnosed as having AD. In multivariate models adjusted for age, education, apolipoprotein E epsilon4 genotype, total energy intake, alcohol intake, smoking habits, body mass index, and supplement use, higher intake of vitamin E at study baseline was associated with lower long-term risk of dementia (P = .02 for trend). Compared with participants in the lowest tertile of vitamin E intake, those in the highest tertile were 25% less likely to develop dementia (hazard ratio, 0.75; 95% confidence interval, 0.59-0.95 with adjustment for potential confounders). Dietary intake levels of vitamin C, beta carotene, and flavonoids were not associated with dementia risk after multivariate adjustment (P > .99 for trend for vitamin C and beta carotene and P = .60 for trend for flavonoids). Results were similar when risk for AD was specifically assessed. CONCLUSION Higher intake of foods rich in vitamin E may modestly reduce long-term risk of dementia and AD.

Dietary Intakes of Berries and Flavonoids in Relation to Cognitive Decline

Berries are high in flavonoids, especially anthocyanidins, and improve cognition in experimental studies. We prospectively evaluated whether greater long‐term intakes of berries and flavonoids are associated with slower rates of cognitive decline in older women.

Dietary intake of fish and omega-3 fatty acids in relation to long-term dementia risk

BACKGROUND Greater fish and omega-3 (n-3) polyunsaturated fatty acid (PUFA) intake may reduce dementia risk; however, previous studies have reported conflicting results, which were largely based on short-term follow-up. OBJECTIVE The objective was to study the dietary consumption of fish and omega-3 PUFAs in relation to long-term dementia risk. DESIGN We studied 5395 participants aged > or =55 y in the Rotterdam Study who were free of dementia and reported dietary information at baseline. We used age- and sex-adjusted Cox proportional hazard and multivariate-adjusted models to evaluate the relative risk of dementia and Alzheimer disease (AD) across categories of typical fish intake (none, low, and high) and fish type consumed (none, lean, and fatty). We also evaluated dementia and AD risk across tertiles of omega-3 PUFA intake, specifically, total long-chain omega-3 fatty acids: eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), alpha-linolenic acid, and EPA and DHA individually. RESULTS During an average follow-up of 9.6 y, dementia developed in 465 participants (365 with a diagnosis of AD). In multivariate-adjusted models, total fish intake was unrelated to dementia risk (P for trend = 0.7). Compared with participants who typically ate no fish, those with a high fish intake had a similar dementia risk (hazard ratio: 0.95; 95% CI: 0.76, 1.19), as did those who typically ate fatty fish (hazard ratio: 0.98; 95% CI: 0.77, 1.24). Dietary intakes of omega-3 PUFAs were also not associated with dementia risk, and the results were similar when we considered AD specifically. CONCLUSION In this Dutch cohort, who had a moderate consumption of fish and omega-3 PUFAs, these dietary factors do not appear to be associated with long-term dementia risk.

Night shift work at specific age ranges and chronic disease risk factors.

Objectives We examined the association of night shift work history and age when night shift work was performed with cancer and cardiovascular disease risk factors among 54 724 women in the Nurses’ Health Study (NHS) II. Methods We calculated age-adjusted and socioeconomic status-adjusted means and percentages for cancer and cardiovascular risk factors in 2009 across categories of night shift work history. We used multivariable-adjusted logistic regression to estimate odds ratios (ORs) and 95% CIs for key risk factors among 54 724 participants (72% ever shift workers). We further examined these associations by age (20–25, 26–35, 36–45 and 46+ years) at which shift work was performed. Results Ever night shift workers had increased odds of obesity (body mass index ≥30 kg/m2; OR=1.37, 95% CI 1.31 to 1.43); higher caffeine intake (≥131 mg/day; OR=1.16, 95% CI 1.12 to 1.22) and total calorie intake (≥1715 kcal/day; OR=1.09, 95% CI 1.04 to 1.13); current smoking (OR=1.30, 95% CI 1.19 to 1.42); and shorter sleep durations (≤7 h of sleep/day; OR=1.19, 95% CI 1.15 to 1.24) compared to never night shift workers. These estimates varied depending on age at which night work was performed, with a suggestion that night shift work before age 25 was associated with fewer risk factors compared to night shift work at older ages. Conclusions Our results indicate that night shift work may contribute to an adverse chronic disease risk profile, and that risk factors may vary depending on the age at which night shift work was performed.

Sleep Duration in Midlife and Later Life in Relation to Cognition

To evaluate associations between sleep duration at midlife and later life and change in sleep duration over time and cognition in older women.

Mismatch of Sleep and Work Timing and Risk of Type 2 Diabetes

OBJECTIVE To examine whether a mismatch between chronotype (i.e., preferred sleep timing) and work schedule is associated with type 2 diabetes risk. RESEARCH DESIGN AND METHODS In the Nurses’ Health Study 2, we followed 64,615 women from 2005 to 2011. Newly developed type 2 diabetes was the outcome measure (n = 1,452). A question on diurnal preference ascertained chronotype in 2009; rotating night shift work exposure was assessed regularly since 1989. RESULTS Compared with intermediate chronotypes, early chronotypes had a slightly decreased diabetes risk after multivariable adjustment (odds ratio 0.87 [95% CI 0.77–0.98]), whereas no significant association was observed for late chronotypes (1.04 [0.89–1.21]). Among early chronotypes, risk of type 2 diabetes was modestly reduced when working daytime schedules (0.81 [0.63–1.04]) and remained similarly reduced in women working <10 years of rotating night shifts (0.84 [0.72–0.98]). After ≥10 years of shift work exposure, early chronotypes had a nonsignificant elevated diabetes risk (1.15 [0.81–1.63], Ptrend = 0.014). By contrast, among late chronotypes, the significantly increased diabetes risk observed among day workers (1.51 [1.13–2.02]) appeared largely attenuated if their work schedules included night shifts (<10 years: 0.93 [0.76–1.13]; ≥10 years: 0.87 [0.56–1.34]; Ptrend = 0.14). The interaction between chronotype and shift work exposure was significant (Pinteraction = 0.0004). Analyses restricting to incident cases revealed similar patterns. CONCLUSIONS In early chronotypes, type 2 diabetes risk increased with increasing duration of shift work exposure, whereas late types had the highest diabetes risk working daytime schedules. These data add to the growing body of evidence that workers could benefit from shift schedules minimizing interference with chronotype-dependent sleep timing.

Long-term intake of nuts in relation to cognitive function in older women

ObjectiveNuts contain nutrients that may benefit brain health; thus, we examined long-term intake of nuts in relation to cognition in older women.DesignPopulation-based prospective cohort study.SettingAcademic research using data from the Nurses’ Health Study.ParticipantsNut intake was assessed in a food-frequency questionnaire beginning inl980, and approximately every four years thereafter. Between 1995–2001, 16,010 women age 70 or older (mean age = 74 years) without a history of stroke were administered 4 repeated telephone-based cognitive interviews over 6 years. Our final sample included 15,467 women who completed an initial cognitive interview and had complete information on nut intake.Main Outcome MeasuresThe Telephone Interview for Cognitive Status (TICS), a global score averaging the results of all tests (TICS, immediate and delayed verbal recall, category fluency, and attention), and a verbal memory score averaging the results of tests of verbal recall.ResultsIn multivariable-adjusted linear regression models, higher long-term total nut intake was associated with better average cognitive status for all cognitive outcomes. For the global composite score combining all tests, women consuming at least 5 servings of nuts/week had higher scores than non-consumers (mean difference=0.08 standard units, 95% confidence interval 0.00–0.15; p-trend=0.003). This mean difference of 0.08 is equivalent to the mean difference we find between women 2 years apart in age. Long-term intake of nuts was not associated with rates of cognitive decline.ConclusionsHigher nut intake may be related to better overall cognition at older ages, and could be an easily-modifiable public health intervention.

Chronotype and Breast Cancer Risk in a Cohort of US Nurses

The aim of this study was to examine the relation between chronotype and breast cancer risk. We analyzed the association between chronotype (definite morning type, probable morning type, probable evening type, definite evening type, or neither morning nor evening type) and breast cancer risk among 72 517 women in the Nurses’ Health Study II (NHS II). Chronotype was self-reported in 2009, and 1834 breast cancer cases were confirmed among participants between 1989 and 2007; a 2-yr lag period was imposed to account for possible circadian disruptions related to breast cancer diagnosis. Age- and multivariable-adjusted logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Participants who self-reported as neither morning nor evening type had a 27% increased risk of breast cancer (multivariable-adjusted OR = 1.27, 95% CI = 1.04–1.56), compared with definite morning types. None of the other chronotypes were significantly associated with breast cancer risk (multivariable-adjusted OR = 0.99, 95% CI = 0.87–1.12 for probable morning versus definite morning types; OR = 0.96, 95% CI = 0.84–1.09 for probable evening versus definite morning types; and OR = 1.15, 95% CI = 0.98–1.34 for definite evening versus definite morning types). Overall, chronotype was not associated with breast cancer risk in our study. A modestly increased risk among neither morning nor evening types may indicate circadian disruption as a potentially underlying mechanism; however, more studies are needed to confirm our results.

Plasma vitamin d levels and cognitive function in aging women: The nurses’ health study

BackgroundVitamin D may play a role in preserving cognitive function. However, there is a paucity of prospective studies on the relationship between vitamin D and cognition with aging. The aim of this study was to examine the association between plasma levels of vitamin D and subsequent cognitive function.MethodsThis is a prospective study including 1,185 women aged 60–70 years from the Nurses’ Health Study, who had plasma 25-hydroxy-vitamin D levels measured in 1989–1990 and completed an initial Telephone Interview of Cognitive Status approximately 9 years later. Subsequently, three follow-up cognitive assessments were conducted at 1.5–2.0 years intervals. We used multivariable-adjusted linear regression to model initial cognitive function, and mixed linear regression to model change in cognitive function over time.ResultsLower vitamin D levels were associated with significantly worse cognitive function 9 years later. For example, the mean global composite score averaging all the cognitive tests was 0.20 lower (95% Confidence Interval (CI):−0.33,−0.08; p-trend=0.009) in women in the lowest quintile (median=14.1 ng/mL) compared with women in the highest quintile of vitamin D (median=38.4 ng/mL). The observed differences were equivalent to the effect estimates we found for women who were approximately 4–6 years apart in age. However, vitamin D levels were not significantly associated with subsequent cognitive decline during 6 years of follow-up.ConclusionsHigher levels of plasma vitamin D in women aged 60–70 years were associated with better cognitive function about a decade later but were not associated with cognitive decline during 6 years of follow-up.

Total antioxidant capacity of the diet and major neurologic outcomes in older adults

Objective: To evaluate total antioxidant capacity of the diet, measured by the ferric-reducing antioxidant power (FRAP) assay, in relation to risks of dementia and stroke, as well as key structural brain volumes, in the elderly. Methods: We prospectively studied 5,395 participants in the Rotterdam Study, aged 55 years and older, who were dementia free and provided dietary information at study baseline; 5,285 individuals were also stroke free at baseline, and 462 were dementia and stroke free at the time of an MRI brain scan 5 years after baseline. Dietary data were ascertained using a semiquantitative food-frequency questionnaire, and combined with food-specific FRAP measurements from published tables; this information was aggregated across the diet to obtain “dietary FRAP scores.” Multivariable-adjusted Cox proportional hazard models were used to estimate relative risks of dementia and stroke, and multivariable-adjusted linear regression was used to estimate mean differences in structural brain volumes, across tertiles of dietary FRAP scores. Results: During a median 13.8 years of follow-up, we identified approximately 600 cases each of dementia and stroke. In multivariable-adjusted models, we observed no associations between dietary FRAP scores and risk of dementia (p trend = 0.3; relative risk = 1.12, 95% confidence interval = 0.91–1.38, comparing the highest vs lowest FRAP tertiles) or risk of stroke (p trend = 0.3; relative risk = 0.91, 95% confidence interval = 0.75–1.11, comparing extreme FRAP tertiles); results were similar across subtypes of these outcomes. Dietary FRAP scores were unrelated to brain tissue volumes as well. Conclusions: Total antioxidant capacity of the diet, measured by dietary FRAP scores, does not seem to predict risks of major neurologic diseases.