BackgroundCurrent projections of the scale of the coming dementia epidemic assume that the age- and sex-specific prevalence of dementia will not vary over time, and that population ageing alone (increasing the number of older people at risk) drives the projected increases. The basis for this assumption is doubtful, and secular trends (that is, gradual decreases or increases in prevalence over long-term periods) are perfectly plausible.MethodsWe carried out a systematic review of studies of trends in prevalence, incidence and mortality for people with dementia, conducted since 1980.ResultsWe identified nine studies that had tracked dementia prevalence, eight that had tracked dementia incidence, and four that had tracked mortality among people with dementia. There was some moderately consistent evidence to suggest that the incidence of dementia may be declining in high-income countries. Evidence on trends in the prevalence of dementia were inconsistent across studies and did not suggest any clear overall effect. Declining incidence may be balanced by longer survival with dementia, although mortality trends have been little studied. There is some evidence to suggest increasing prevalence in East Asia, consistent with worsening cardiovascular risk factor profiles, although secular changes in diagnostic criteria may also have contributed.ConclusionsWe found no evidence to suggest that the current assumption of constant age-specific prevalence of dementia over time is ill-founded. However, there remains some uncertainty as to the future scale of the dementia epidemic. Population ageing seems destined to play the greatest role, and prudent policymakers should plan future service provision based upon current prevalence projections. Additional priorities should include investing in brain health promotion and dementia prevention programs, and monitoring the future course of the epidemic to chart the effectiveness of these measures.

IntroductionIn 2010, Alzheimer's Disease International presented estimates of the global cost of illness (COI) of dementia. Since then, new studies have been conducted, and the number of people with dementia has increased. Here, we present an update of the global cost estimates.MethodsThis is a societal, prevalence-based global COI study.ResultsThe worldwide costs of dementia were estimated at United States (US) $818 billion in 2015, an increase of 35% since 2010; 86% of the costs occur in high-income countries. Costs of informal care and the direct costs of social care still contribute similar proportions of total costs, whereas the costs in the medical sector are much lower. The threshold of US $1 trillion will be crossed by 2018.DiscussionWorldwide costs of dementia are enormous and still inequitably distributed. The increase in costs arises from increases in numbers of people with dementia and in increases in per person costs.

This meta-analysis points to a reciprocal interaction between depression and frailty in older adults. Specifically, each condition is associated with an increased prevalence and incidence of the other, and may be a risk factor for the development of the other. However, further prospective investigations are warranted.

The pathogenesis of frailty and the role of inflammation is poorly understood. We examined the evidence considering the relationship between inflammation and frailty through a systematic review and meta-analysis. A systematic literature search of papers providing data on inflammatory biomarkers and frailty was carried out in major electronic databases from inception until May 2016. From 1856 initial hits, 35 studies (32 cross-sectional studies n=3232 frail, n=11,483 pre-frail and n=8522 robust, and 563 pre-frail+robust; 3 longitudinal studies n=3402 participants without frailty at baseline) were meta-analyzed. Cross-sectional studies reported that compared to 6757 robust participants, both 1698 frail (SMD=1.00, 95%CI: 0.40-1.61) and 8568 pre-frail (SMD=0.33, 95%CI: 0.04-0.62) participants had significantly higher levels of C-reactive protein (CRP). Frailty (n=1057; SMD=1.12, 95%CI: 0.27-2.13) and pre-frailty (n=4467; SMD=0.56, 95%CI: 0.00-1.11) were associated with higher serum levels of interleukin-6 compared to people who were robust (n=2392). Frailty and pre-frailty were also significantly associated with elevated white blood cell and fibrinogen levels. In three longitudinal studies, higher serum CRP (OR=1.06, 95%CI: 0.78-1.44,) and IL-6 (OR=1.19, 95%CI: 0.87-1.62) were not associated with frailty. In conclusion, frailty and pre-frailty are associated with higher inflammatory parameters and in particular CRP and IL-6. Further longitudinal studies are needed.

Background: With ageing world populations, multimorbidity (presence of two or more chronic diseases in the same individual) becomes a major concern in public health. Although multimorbidity is associated with age, its prevalence varies. This systematic review aimed to summarise and meta-analyse the prevalence of multimorbidity in high, low- and middle-income countries (HICs and LMICs). Methods: Studies were identified by searching electronic databases (Medline, Embase, PsycINFO, Global Health, Web of Science and Cochrane Library). The term ‘multimorbidity’ and its various spellings were used, alongside ‘prevalence’ or ‘epidemiology’. Quality assessment employed the Newcastle-Ottawa scale. Overall and stratified analyses according to multimorbidity operational definitions, HICs/LMICs status, gender and age were performed. A random-effects model for meta-analysis was used. Results: Seventy community-based studies (conducted in 18 HICs and 31 LMICs) were included in the final sample. Sample sizes ranged from 264 to 162,464. The overall pooled prevalence of multimorbidity was 33.1% (95% confidence interval (CI): 30.0–36.3%). There was a considerable difference in the pooled estimates between HICs and LMICs, with prevalence being 37.9% (95% CI: 32.5–43.4%) and 29.7% (26.4–33.0%), respectively. Heterogeneity across studies was high for both overall and stratified analyses ( I 2 > 99%). A sensitivity analysis showed that none of the reviewed studies skewed the overall pooled estimates. Conclusion: A large proportion of the global population, especially those aged 65+, is affected by multimorbidity. To allow accurate estimations of disease burden, and effective disease management and resources distribution, a standardised operationalisation of multimorbidity is needed.