Laura Fratiglioni

Global prevalence of dementia: a Delphi consensus study.

BACKGROUND 100 years after the first description, Alzheimers disease is one of the most disabling and burdensome health conditions worldwide. We used the Delphi consensus method to determine dementia prevalence for each world region. METHODS 12 international experts were provided with a systematic review of published studies on dementia and were asked to provide prevalence estimates for every WHO world region, for men and women combined, in 5-year age bands from 60 to 84 years, and for those aged 85 years and older. UN population estimates and projections were used to estimate numbers of people with dementia in 2001, 2020, and 2040. We estimated incidence rates from prevalence, remission, and mortality. FINDINGS Evidence from well-planned, representative epidemiological surveys is scarce in many regions. We estimate that 24.3 million people have dementia today, with 4.6 million new cases of dementia every year (one new case every 7 seconds). The number of people affected will double every 20 years to 81.1 million by 2040. Most people with dementia live in developing countries (60% in 2001, rising to 71% by 2040). Rates of increase are not uniform; numbers in developed countries are forecast to increase by 100% between 2001 and 2040, but by more than 300% in India, China, and their south Asian and western Pacific neighbours. INTERPRETATION We believe that the detailed estimates in this paper constitute the best currently available basis for policymaking, planning, and allocation of health and welfare resources.

Mild cognitive impairment : beyond controversies, towards a consensus : report of the International Working Group on Mild Cognitive Impairment

The First Key Symposium was held in Stockholm, Sweden, 2–5 September 2003. The aim of the symposium was to integrate clinical and epidemiological perspectives on the topic of Mild Cognitive Impairment (MCI). A multidisciplinary, international group of experts discussed the current status and future directions of MCI, with regard to clinical presentation, cognitive and functional assessment, and the role of neuroimaging, biomarkers and genetics. Agreement on new perspectives, as well as recommendations for management and future research were discussed by the international working group. The specific recommendations for the general MCI criteria include the following: (i) the person is neither normal nor demented; (ii) there is evidence of cognitive deterioration shown by either objectively measured decline over time and/or subjective report of decline by self and/or informant in conjunction with objective cognitive deficits; and (iii) activities of daily living are preserved and complex instrumental functions are either intact or minimally impaired.

The impact of chronic multimorbidity and disability on functional decline and survival in elderly persons. A community‐based, longitudinal study

Objective.  We aimed to disentangle the effect of chronic multimorbidity and disability on 3‐year functional decline and survival in the elderly.

An active and socially integrated lifestyle in late life might protect against dementia

The recent availability of longitudinal data on the possible association of different lifestyles with dementia and Alzheimers disease (AD) allow some preliminary conclusions on this topic. This review systematically analyses the published longitudinal studies exploring the effect of social network, physical leisure, and non-physical activity on cognition and dementia and then summarises the current evidence taking into account the limitations of the studies and the biological plausibility. For all three lifestyle components (social, mental, and physical), a beneficial effect on cognition and a protective effect against dementia are suggested. The three components seem to have common pathways, rather than specific mechanisms, which might converge within three major aetiological hypotheses for dementia and AD: the cognitive reserve hypothesis, the vascular hypothesis, and the stress hypothesis. Taking into account the accumulated evidence and the biological plausibility of these hypotheses, we conclude that an active and socially integrated lifestyle in late life protects against dementia and AD. Further research is necessary to better define the mechanisms of these associations and better delineate preventive and therapeutic strategies.

Influence of social network on occurrence of dementia: a community-based longitudinal study

BACKGROUND Few data are available on the effect of social ties on dementia development. This study explored whether single social network components and different degrees of the social connections affect dementia incidence. METHODS A community-based cohort of 1203 non-demented people, living at home in the Kungsholmen district of Stockholm, Sweden, and who had good cognition, was followed for an average period of 3 years. On the basis of medical and psychological data, 176 patients were diagnosed with dementia according to the criteria of the third edition revision of the Diagnostic and Statistical Manual of Mental Disorders. Information on social network was obtained by personal interview by trained nurses at baseline. The covariates included in the analysis were age, sex, education, cognitive and functional status, depressive symptoms, and vascular diseases. FINDINGS Those individuals living alone, and those without any close social ties, both had an adjusted relative risk for developing dementia of 1.5 (95% CI 1.0-2.1 and 1.0-2.4, respectively). Compared with married people living with someone, single people and those living alone had an adjusted relative risk of 1.9 (95% CI 1.2-3.1). Infrequent contacts with network resources did not increase the risk of the disease if such contacts were experienced as satisfying. When all components were combined in an index, a poor or limited social network increased the risk of dementia by 60% (95% CI 1.2-2.1), and a significant gradient was found for the four degrees of social connections (p=0.0009). INTERPRETATION An extensive social network seems to protect against dementia. Confirmation of this finding and further investigation to clarify the mechanisms are worthwhile due to the implications for prevention.

Aging with multimorbidity: A systematic review of the literature

A literature search was carried out to summarize the existing scientific evidence concerning occurrence, causes, and consequences of multimorbidity (the coexistence of multiple chronic diseases) in the elderly as well as models and quality of care of persons with multimorbidity. According to pre-established inclusion criteria, and using different search strategies, 41 articles were included (four of these were methodological papers only). Prevalence of multimorbidity in older persons ranges from 55 to 98%. In cross-sectional studies, older age, female gender, and low socioeconomic status are factors associated with multimorbidity, confirmed by longitudinal studies as well. Major consequences of multimorbidity are disability and functional decline, poor quality of life, and high health care costs. Controversial results were found on multimorbidity and mortality risk. Methodological issues in evaluating multimorbidity are discussed as well as future research needs, especially concerning etiological factors, combinations and clustering of chronic diseases, and care models for persons affected by multiple disorders. New insights in this field can lead to the identification of preventive strategies and better treatment of multimorbid patients.

The age-dependent relation of blood pressure to cognitive function and dementia

The relation of blood pressure with cognitive function and dementia has, in recent years, received much attention from epidemiological research. Some cross-sectional studies have shown an inverse association between blood pressure and the prevalence of dementia and Alzheimers disease, whereas longitudinal studies yield mixed results that largely depend on the age at which blood pressure is measured and the time interval between blood pressure and outcome assessments. Some studies suggest that midlife high blood pressure is a risk factor for late-life cognitive impairment and dementia, and that low diastolic pressure and very high systolic pressure in older adults may be associated with subsequent development of dementia and Alzheimers disease. Observational studies and randomised clinical trials provide limited evidence for a protective effect of antihypertensive therapy against dementia and stroke-related cognitive decline. Atherosclerosis resulting from long-standing hypertension, and cerebral hypoperfusion secondary to severe atherosclerosis and to low blood pressure may be major biological pathways linking both high blood pressure in midlife and low blood pressure in late-life to cognitive decline and dementia.

Air pollution and lung cancer incidence in 17 European cohorts: prospective analyses from the European Study of Cohorts for Air Pollution Effects (ESCAPE)

BACKGROUND Ambient air pollution is suspected to cause lung cancer. We aimed to assess the association between long-term exposure to ambient air pollution and lung cancer incidence in European populations. METHODS This prospective analysis of data obtained by the European Study of Cohorts for Air Pollution Effects used data from 17 cohort studies based in nine European countries. Baseline addresses were geocoded and we assessed air pollution by land-use regression models for particulate matter (PM) with diameter of less than 10 μm (PM10), less than 2·5 μm (PM2·5), and between 2·5 and 10 μm (PMcoarse), soot (PM2·5absorbance), nitrogen oxides, and two traffic indicators. We used Cox regression models with adjustment for potential confounders for cohort-specific analyses and random effects models for meta-analyses. FINDINGS The 312 944 cohort members contributed 4 013 131 person-years at risk. During follow-up (mean 12·8 years), 2095 incident lung cancer cases were diagnosed. The meta-analyses showed a statistically significant association between risk for lung cancer and PM10 (hazard ratio [HR] 1·22 [95% CI 1·03-1·45] per 10 μg/m(3)). For PM2·5 the HR was 1·18 (0·96-1·46) per 5 μg/m(3). The same increments of PM10 and PM2·5 were associated with HRs for adenocarcinomas of the lung of 1·51 (1·10-2·08) and 1·55 (1·05-2·29), respectively. An increase in road traffic of 4000 vehicle-km per day within 100 m of the residence was associated with an HR for lung cancer of 1·09 (0·99-1·21). The results showed no association between lung cancer and nitrogen oxides concentration (HR 1·01 [0·95-1·07] per 20 μg/m(3)) or traffic intensity on the nearest street (HR 1·00 [0·97-1·04] per 5000 vehicles per day). INTERPRETATION Particulate matter air pollution contributes to lung cancer incidence in Europe. FUNDING European Communitys Seventh Framework Programme.

Prevalence of Alzheimer's disease and other dementias in an elderly urban population Relationship with age, sex, and education

We studied the prevalence of different types of dementia in an elderly population in Stockholm, Sweden, in relation to age, sex, and education. The study confirmed Alzheimers disease (AD) as the most frequent type of dementia and the positive association of dementias with age, even in the most advanced ages. In contrast to previously reported data, we found the same proportion of AD and vascular dementia in the different age strata, and no sex differences regarding the prevalence of different dementia types. Finally, less educated people had a higher prevalence of all dementias, due essentially to a higher prevalence of alcoholic dementia and unspecified type of dementia. The prevalence of AD was similar across different levels of education.

Very Old Women at Highest Risk of Dementia and Alzheimer's Disease Incidence Data from the Kungsholmen Project, Stockholm

Objective: To determine the incidence of different types of dementia in the very old, and to explore the relation with age and gender. Design: A dementia-free cohort was followed for an average of three years in Stockholm, Sweden. At the end of the follow-up, the subjects were interviewed by nurses, clinically examined by physicians, and cognitively assessed by psychologists. Deceased cohort members were studied using death certificates, hospital clinical records, and discharge diagnoses. Dementia diagnoses were made according to the DSM-III-R criteria independently by two physicians. Participants: The cohort consisted of 1,473 subjects (75+ years old), of which 987 were clinically examined at follow-up, 314 died before the examination, and 172 refused to participate. Results: During the follow-up, 148 subjects developed dementia. In the age-group 75 to 79, the incidence rates for dementia were 19.6 for women and 12.4 for men per 1,000 person-years, whereas for 90+ year-old subjects the corresponding figures were 86.7 and 15.0 per 1,000 person-years. A similar pattern of distribution by age and gender was seen for Alzheimers disease. In each age stratum, the incidence rates of dementia and Alzheimers disease were higher for women than for men. The age-adjusted odds ratio for women was 1.9 for dementia and 3.1 for Alzheimers disease. Conclusions: (1) The incidence of dementia increases with age, even in the oldest age groups; (2) women have a higher risk of developing dementia than men, especially at very old ages; (3) this pattern is mainly due to the age and gender distribution of Alzheimers disease, rather than vascular dementia. NEUROLOGY 1997;48: 132-138