Purpose of review Trouble falling or staying asleep, poor sleep quality, and short or long sleep duration are gaining attention as potential risk factors for cognitive decline and dementia, including Alzheimer's disease (AD). Sleep-disordered breathing (SDB) has also been linked to these outcomes. Here, we review recent observational and experimental studies investigating the effect of poor sleep on cognitive outcomes and AD and discuss possible mechanisms. Recent findings Observational studies with self-report and objective sleep measures (e.g., wrist actigraphy, polysomnography) support links between disturbed sleep and cognitive decline. Several recently published studies demonstrate associations between sleep variables and measures of AD pathology, including cerebrospinal fluid measures (CSF) of Aβ and positron emission tomography (PET) measures of Aβ deposition. In addition, experimental studies suggest that sleep loss alters CSF Aβ dynamics, that decrements in slow-wave sleep may decrease the clearance of Aβ from the brain, and that hypoxemia characteristic of SDB increases Aβ production. Summary Findings indicate that poor sleep is a risk factor for cognitive decline and AD. Although mechanisms underlying these associations are not yet clear, healthy sleep appears to play an important role in maintaining brain health with age, and may play a key role in AD prevention.

Iron deficiency anemia and child mortality are public health problems requiring urgent attention. However, the degree to which iron deficiency anemia contributes to child mortality is unknown. Here, we utilized an exhaustive article search and screening process to identify articles containing both anemia and mortality data for children aged 28 days to 12 years. We then estimated the reduction in risk of mortality associated with a 1-g/dL increase in hemoglobin (Hb). Our meta-analysis of nearly 12,000 children from six African countries revealed a combined odds ratio of 0.76 (0.62–0.93), indicating that for each 1-g/dL increase in Hb, the risk of death falls by 24%. The feasibility of a 1-g/dL increase in Hb has been demonstrated via simple iron supplementation strategies. Our finding suggests that ~1.8 million deaths in children aged 28 days to five years could be avoided each year by increasing Hb in these children by 1 g/dL.

OBJECTIVES Insomnia is reported to be more prevalent in minority racial/ethnic groups. Little is known, however, about racial/ethnic differences in changes in insomnia severity over time, particularly among older adults. We examined racial/ethnic differences in trajectories of insomnia severity among middle-aged and older adults. DESIGN Data were drawn from five waves of the Health and Retirement Study (2002–2010), a nationally representative longitudinal biennial survey of adults aged >50. SETTING Population-based. PARTICIPANTS 22,252 participants from non-Hispanic white, non-Hispanic black, Hispanic, and other racial/ethnic groups. INTERVENTION N/A MEASUREMENTS Participants reported the severity of four insomnia symptoms; summed scores ranged from 4 (no insomnia) to 12 (severe insomnia). We assessed change in insomnia across the five waves as a function of race/ethnicity. RESULTS Across all participants, insomnia severity scores increased 0.19 points (95% CI=0.14, 0.24; t=7.52; design df=56; p<0.001) over time after adjustment for gender, race/ethnicity, education, and baseline age. After adjusting for the number of accumulated health conditions and BMI, this trend decreased substantially and even changed direction (B=−0.24; 95% CI=−0.29, −0.19; t=−9.22; design df=56; p<0.001). The increasing trajectory was significantly more pronounced in Hispanics compared to non-Hispanic whites, even after adjustment for number of accumulated health conditions, BMI, and number of depressive symptoms. CONCLUSIONS Although insomnia severity increases with age—largely due to the accumulation of health conditions—this trend appears more pronounced among Hispanic older adults than in non-Hispanic whites. Further research is needed to determine the reasons for a different insomnia trajectory among Hispanics.

Background We determined the association between neighborhood socio-environmental factors and insomnia symptoms in a nationally representative sample of US adults aged >50 years. Methods Data were analyzed from two waves (2006 and 2010) of the Health and Retirement Study using 7,231 community-dwelling participants (3,054 men and 4,177 women) in the United States. Primary predictors were neighborhood physical disorder (e.g., vandalism/graffiti, feeling safe alone after dark, cleanliness) and social cohesion (e.g., friendliness of people, availability of help when needed); outcomes were insomnia symptoms (trouble falling asleep, night awakenings, waking too early, feeling unrested). Results After adjustment for age, income, race, education, sex, chronic diseases, body mass index, depressive symptoms, smoking, and alcohol consumption, each one-unit increase in neighborhood physical disorder was associated with a greater odds of trouble falling asleep (odds ratio (OR)=1.09, 95% confidence interval (CI) 1.04–1.14), waking too early (OR=1.05, 95% CI 1.00–1.10), and, in adults aged ≥69 (adjusting for all variables above except age), feeling unrested in the morning (OR=1.11, 95% CI 1.02–1.22 in 2006). Each one-unit increase in lower social cohesion was associated with a greater odds of trouble falling asleep (OR=1.06, 95% CI 1.01–1.11) and feeling unrested (OR=1.09, 95% CI 1.04–1.15). Conclusions Neighborhood-level factors of physical disorder and social cohesion are associated with insomnia symptoms in middle-aged and older adults. Neighborhood-level factors may affect sleep, and consequently health, in our aging population.

Background The prevalence of both type II diabetes mellitus (DM) and cognitive impairment is high and increasing in older adults. We examined the extent to which DM diagnosis was associated with poorer cognitive performance and dementia diagnosis in a population-based cohort of US older adults. Methods We studied 7,606 participants in the National Health and Aging Trends Study, a nationally representative cohort of Medicare beneficiaries aged 65 years and older. DM and dementia diagnosis were based on self-report from participants or proxy respondents, and participants completed a word-list memory test, the Clock Drawing Test, and gave a subjective assessment of their own memory. Results In unadjusted analyses, self-reported DM diagnosis was associated with poorer immediate and delayed word recall, worse performance on the Clock Drawing Test, and poorer self-rated memory. After adjusting for demographic characteristics, body mass index, depression and anxiety symptoms, and medical conditions, DM was associated with poorer immediate and delayed word recall and poorer self-rated memory, but not with the Clock Drawing Test performance or self-reported dementia diagnosis. After excluding participants with a history of stroke, DM diagnosis was associated with poorer immediate and delayed word recall and the Clock Drawing Test performance, and poorer self-rated memory, but not with self-reported dementia diagnosis. Conclusions In this recent representative sample of older Medicare enrollees, self-reported DM was associated with poorer cognitive test performance. Findings provide further support for DM as a potential risk factor for poor cognitive outcomes. Studies are needed that investigate whether DM treatment prevents cognitive decline.