Dementia is an increasing focus for policymakers, civil organizations and multidisciplinary researchers. The most recent descriptive epidemiological research into dementia is enabling investigation ...into how the prevalence and incidence are changing over time. To establish clear trends, such comparisons need to be founded on population-based studies that use similar diagnostic and research methods consistently over time. This narrative Review synthesizes the findings from 14 studies that investigated trends in dementia prevalence (nine studies) and incidence (five studies) from Sweden, Spain, the UK, the Netherlands, France, the USA, Japan and Nigeria. Besides the Japanese study, these studies indicate stable or declining prevalence and incidence of dementia, and some provide evidence of sex-specific changes. No single risk or protective factor has been identified that fully explains the observed trends, but major societal changes and improvements in living conditions, education and healthcare might have favourably influenced physical, mental and cognitive health throughout an individual's life course, and could be responsible for a reduced risk of dementia in later life. Analytical epidemiological approaches combined with translational neuroscientific research could provide a unique opportunity to explore the neuropathology that underlies changing occurrence of dementia in the general population.
•Exploring the effects of long-term exposure to air pollution on dementia incidence.•PM2.5 level was associated with Alzheimer’s disease and vascular dementia incidence.•No association was detected ...between NO2 or black carbon exposure and dementia risk.•PM2.5 might be a modifiable risk factor of the main forms of dementia.
Emerging epidemiological evidence suggests a relationship between exposure to air pollution and dementia. However, most of the existing studies relied on health administrative databases for the diagnosis of dementia. In a large French population-based cohort (the 3C Study), we assessed the effects of particulate matter ≤2.5 µm (PM2.5), nitrogen dioxide (NO2) and black carbon (BC) on the risk of dementia diagnosed with reliable tools.
Participants aged ≥65 years were recruited between 1999 and 2001 and followed for 12 years. At baseline and every 2 years, dementia was suspected on the basis of the neuropsychological and neurological examination and confirmed by an independent committee of clinicians. Exposure to NO2, BC and PM2.5 at the participants’ residential address was estimated using land use regression models. For each pollutant and year of follow-up, the 10-year moving average of past exposure was estimated. Multilevel spatial random-effects Cox proportional hazards models were used in which exposure was included as a time-varying variable. Analyses were adjusted for individual (age, sex, education, APOE4 genotype, health behaviours) and contextual (neighbourhood deprivation index) confounders.
At baseline, the median age of the 7066 participants was 73.4 years, and 62% were women. The median follow-up duration was 10.0 years during which 791 participants developed dementia (n = 541 Alzheimer’s disease (AD) and n = 155 vascular/mixed dementia (VaD)). The 10-year moving average of PM2.5 concentrations ranged from 14.6 to 31.3 µg/m3.
PM2.5 concentration was positively associated with dementia risk: HR = 1.20, 95% CI (1.08–1.32) for all-cause dementia, 1.20 (1.09–1.32) for AD, and 1.33 (1.05–1.68) for VaD per 5 µg/m3 PM2.5 increase. No association was detected between NO2 or BC exposure and dementia risk.
In this large cohort of older adults, long-term PM2.5 exposure was associated with increased dementia incidence. Reducing PM2.5 emissions might lessen the burden of dementia in aging populations.
Multiple system atrophy (MSA) is a rare neurodegenerative disease, with limited understanding of disease progression and prognostic factors. We leveraged the data of a large prospective cohort of MSA ...to study both clinical progression and survival and assess their determinants. All consecutive patients seen at the French Reference Centre for MSA since 2007 were included in a prospective cohort with an annual follow-up including the Unified MSA Rating Scale (UMSARS). We used joint models to evaluate the risk of death, the mean trajectory of each UMSARS subscale and to determine the potential factors. Investigated factors included gender, age at baseline, MSA subtype, diagnosis certainty, type of first symptoms and the duration between symptom onset and the first visit. Among the 261 MSA patients included in our cohort, the median duration of clinical follow-up was 2.1 years (up to 10.3 years) and the median survival was 4.0 years since the first visit. Main factors for poor survival were the progression over time of UMSARS score (I + II and IV) and the severity of orthostatic hypotension. MSA subtype had no effect on progression or survival. The UMSARS I + II score progressed faster over time in subjects with autonomic dysfunction as the initial feature and in women. Despite a faster progression, women and men had similar survival. From this large MSA cohort, we confirm the rapid progression and poor prognosis of MSA. We provide additional evidence for a negative impact of early autonomic dysfunction and the severity of orthostatic hypotension on both disease progression and survival.
•Median survival was 4 years since first visit and 9.3 years since symptom onset.•UMSARS I + II progression and severity of orthostatic hypotension were main factors for poor survival.•UMSARS I + II scores progressed faster in subjects with early dysautonomia and women.
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•Air pollution may have deleterious effects on the central nervous system.•In aging, it is important to determine if air pollution exposure accelerates cognitive decline.•We studied ...exposure to three air pollutants: PM2.5, NO2 and black carbon.•Exposure to PM2.5 was associated with accelerated cognitive decline in our cohort.
Growing epidemiological evidence suggests an adverse relationship between exposure to air pollutants and cognitive decline. However, there is still some heterogeneity in the findings, with inconsistent results depending on the pollutant and the cognitive domain considered. We wanted to determine whether air pollution was associated with global and domain-specific cognitive decline.
This analysis used data from the French Three-City prospective cohort (participants aged 65 and older at recruitment and followed for up to 12 years). A battery of cognitive tests was administered at baseline and every 2 years, to assess global cognition (Mini Mental State Examination, MMSE), visual memory (Benton Visual Retention Test), semantic fluency (Isaacs Set Test) and executive functions (Trail Making Tests A and B). Exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2) and black carbon (BC) at the participants’ residential address during the 5 years before the baseline visit was estimated with land use regression models. Linear mixed models and latent process mixed models were used to assess the association of each pollutant with global and domain-specific cognitive decline.
The participants’ (n = 6380) median age was 73.4 years (IQR: 8.0), and 61.5% were women. At baseline, the median MMSE score was 28 (IQR: 3). Global cognition decline, assessed with the MMSE, was slightly accelerated among participants with higher PM2.5 exposure: one IQR increment in PM2.5 (1.5 µg/m3) was associated with accelerated decline (β: −0.0060 −0.0112; −0.0007 standard unit per year). Other associations were inconsistent in direction, and of small magnitude.
In this large population-based cohort, higher PM2.5 exposure was associated with accelerated global cognition decline. We did not detect any significant association for the specific cognitive domains or the other pollutants. Evidence concerning PM2.5 effects on cognition is growing, but more research is needed on other ambient air pollutants.
To analyze the association between dietary patterns and the 12-year risk of frailty and its components in community-dwelling elderly French adults.
A prospective cohort study.
The Bordeaux sample of ...the Three-City Study.
A total of 972 initially nonfrail nondemented participants (336 men and 636 women) aged 73 years on average, re-examined at least once over 12 years.
Five sex-specific dietary clusters were previously derived at baseline. Frailty incident to the baseline visit was defined as having at least three out of the following 5 criteria: unintentional weight loss, exhaustion, low energy expenditure, slowness, and muscle weakness. Multivariate Cox proportional hazard models were used to assess the association between dietary clusters and the risk of frailty and its components.
In total, 78 men for 3719 person-years and 221 women for 7027 person-years became frail over the follow-up. In multivariate analyses, men in the "pasta" pattern and women in the "biscuits and snacking" pattern had a significantly higher risk of frailty compared with those in the "healthy" pattern hazard ratio (HR) 2.2; 95% confidence interval (CI) 1.1-4.4 and HR 1.8; 95% CI 1.2-2.8, respectively; P = .09 and P = .13 for the global test of significance of risk difference across clusters, respectively. In men, "biscuits and snacking" and "pasta" patterns were significantly associated with higher risk for muscle weakness (HR 3.3; 95% CI 1.6-7.0 and HR 2.1; 95% CI 1.2-3.7, respectively; P = .003 for global test).
This 12-year prospective population-based study suggests that some particular unhealthy dietary patterns may increase the risk of frailty in older adults.
Abstract The influence of education, occupation, and leisure activities on the passive and active components of reserve capacity remains unclear. We used the voxel-based morphometry (VBM) technique ...in a population-based sample of 331 nondemented people in order to investigate the relationship between these factors and the cerebral volume (a marker of brain reserve). The results showed a positive and significant association between education, occupation, and leisure activities and the cognitive performances on Isaac's set test. Among these factors, only education was significantly associated with a cerebral volume including gray and white matter ( p = 0.01). In voxel-based morphometry analyses, the difference in gray matter volume was located in the temporoparietal lobes and in the orbitofrontal lobes bilaterally (a p -value corrected <0.05 by false discovery rate FDR). Although smaller, the education-related difference in white matter volume appeared in areas connected to the education-related difference in gray matter volume. Education, occupation attainment, and leisure activities were found to contribute differently to reserve capacity. Education could play a role in the constitution of cerebral reserve capacity.
Dairy products (DP) are part of a food group that may contribute to the prevention of physical frailty. We aimed to investigate DP exposure, including total DP, milk, fresh DP and cheese, and their ...cross-sectional and prospective associations with physical frailty in community-dwelling older adults. The cross-sectional analysis was carried out on 1490 participants from the Three-City Bordeaux cohort. The 10-year frailty risk was examined in 823 initially non-frail participants. A food frequency questionnaire was used to assess DP exposure. Physical frailty was defined as the presence of at least 3 out of 5 criteria of the frailty phenotype: weight loss, exhaustion, slowness, weakness, and low physical activity. Among others, diet quality and protein intake were considered as confounders. The baseline mean age of participants was 74.1 y and 61% were females. Frailty prevalence and incidence were 4.2% and 18.2%, respectively. No significant associations were observed between consumption of total DP or DP sub-types and frailty prevalence or incidence (OR = 1.40, 95%CI 0.65–3.01 and OR = 1.75, 95%CI 0.42–1.32, for a total DP consumption >4 times/d, respectively). Despite the absence of beneficial associations of higher DP consumption on frailty, older adults are encouraged to follow the national recommendations regarding DP.
Sleep disturbances are common in elderly and occur frequently in dementia. The impact of excessive daytime sleepiness (EDS), insomnia complaints, sleep quality, and hypnotics on the risk of all-cause ...dementia, Alzheimer disease (AD), and dementia with vascular component (DVC) remains unclear, as does the association between sleep profile and plasma β-amyloid levels.
Analyses were carried out on 6851 participants aged 65 years and over randomly recruited from three French cities and free of dementia at baseline. A structured interview and self-questionnaire assessed sleep complaints (EDS, insomnia complaints, sleep quality) and medications at baseline. Incident cases of dementia were diagnosed systematically over a 12-year period. Multivariate Cox models were used to estimate the risk of dementia associated with the sleep complaints considered individually and globally. Plasma β-amyloid levels were measured by an xMAP-based assay technology in 984 subjects.
After adjustment for socio-demographic characteristics, lifestyle, APOE-ε4, cardiovascular factors, and depressive status, EDS had a higher risk of all-cause dementia (HR = 1.21; 95%CI = 1.01-1.46) and DVC (HR = 1.58; 95%CI = 1.07-2.32) but not AD. Persistent use of hypnotics increased the risk for all-cause dementia, specifically AD (HR = 1.28; 95%CI = 1.04-1.58), but not DVC. No association was found for insomnia complaints and sleep quality taken as individual factors or combined with EDS on the risk of dementia. No association was found between β-amyloid, sleep complaints, and incident dementia.
The results suggest a deleterious role of EDS and hypnotics on dementia. Further studies are required to elucidate the mechanisms involved in these associations and whether its management can prevent the risk of dementia.
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