Alzheimer's Disease Prevalence Rates Research Articles

Research progress of EGCG in the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a degenerative disease of the nervous system. Mainly presenting with neuropsychiatric symptoms such as progressive memory impairment, cognitive dysfunction, personality changes, and language disorders [1]. Also known as senile dementia, it is the leading cause of dementia in the elderly [2]. Involved in 60-80% of all reports of dementia [3]. As the global population ages, AD prevalence and mortality rates increase. It seriously affects the quality of life of the elderly and brings a heavy economic burden and severe social problems. The tea polyphenol epigallocatechin gallate (EGCG) has preventive and therapeutic effects on Alzheimer's disease by inhibiting the amyloid formation and aggregation, antioxidant, anti-inflammatory, metal chelating, binding cholinesterase, thereby reducing the degradation of acetylcholine, and repairing mitochondrial dysfunction. This article reviews the research on the mechanism of EGCG action on Alzheimer's disease.

Evidence against a geographic gradient of Alzheimer's disease and the hygiene hypothesis

A significant positive correlation was previously reported (Fox et al.Evol Med Public Health 2013; 2013:173–86) between hygiene and the global prevalence of Alzheimer's disease (AD) based on World Health Organization (2004) data. These data have now been updated by the Global Burden of Disease (GBD; 2016) dataset that takes into account under-registration and other potential confounds. We therefore addressed whether the association between hygiene and AD is maintained in light of these more recent data. We report a significant positive correlation between GBD AD prevalence rates and parasite burden, and a negative association with hygiene. These newer data argue that hygiene is not a risk factor for AD, and instead suggest that parasite burden may increase AD risk.Lay summary: It was previously hypothesized that hygeine might be a risk factor for the development of Alzheimer disease (AD), based on a global gradient of dementia. Newer data that correct global AD rates for under-reporting now demonstrate that parasite burden is positively correlated with AD.

A0575 Comparison of prevalence and associated risk factors of dementia, mild cognitive impairment among elderly between common communities and nursing homes

Objectives: This study was conducted to estimate the prevalence and associated risk factors of dementia and mild cognitive impairment (MCI) in nursing homes (NHs) and common communities (CCs) among elderly in Zhejiang province of China. Methods: We conducted an investigation in Southern China in 2014. A total of 2,015 subjects (1107 from CCs and 908 from NHs) aged 65 or older participated in the study. Trained nurses carried out relevant assessments, interviews and collected information. Dementia (alzheimer's disease (AD), vascular dementia (VaD)) and MCI were diagnosed according to the NIA-AA criteria in 2011. Results: Dementia prevalence was 42.4% in NHs, significantly higher than that of CCs (5.3%). The prevalence rates of AD, VaD and MCI were 22.0%, 1.9% and 21.6% respectively in NHs, which were significantly higher than that of CCs (3.5%, 0.3% and 11.0% respectively). Dementia was associated with old age, low education level, having a medical history of stroke and living in NHs. While prevalence of VaD among participants having a medical history of stroke, a habit of smoking and heavy drinking were found a sharp rise. Conclusion: More attention should be paid to NH dementia, and more appropriate NH intervention programs are needed.

Prevalence of Dementia and Main Subtypes in Rural Northern China

Background/Aims: The aim of this article was to estimate the prevalence of and to determine the sociodemographic risk factors for dementia, Alzheimer's disease (AD) and vascular dementia (VaD) among individuals residing in rural northern China. Methods: Between 2011 and 2012, residents aged ≥60 years and residing in rural areas of northern China were clinically assessed for symptoms of dementia, AD and VaD. Diagnoses were made using established criteria and standard procedures. Results: Among 5,578 enrolled study participants aged ≥60 years, the prevalence rates of dementia, AD and VaD were 7.7, 5.4 and 1.7%, respectively. Older age (OR = 1.17; 95% CI: 1.14-1.19) and female gender (OR = 2.13; 95% CI: 1.51-3.00) were identified as independent risk factors for AD. In turn, a higher educational level (OR = 0.36; 95% CI: 0.21-0.60) and engagement in social activities (OR = 0.219; 95% CI: 0.163-0.295) were protective factors. Risk factors associated with VaD were older age (OR = 1.11; 95% CI: 1.1-1.12) and hypertension (OR = 1.83; 95% CI: 1.18-2.86), while a higher educational level (OR = 0.53, 95% CI: 0.44-0.65) and engagement in social activities (OR = 0.34; 95% CI: 0.29-0.41) were protective factors. Conclusion: High rates of dementia (7.7%) and AD (5.4%) were found in the rural areas of northern China. Older age and female gender were identified as risk factors for AD, while older age and hypertension were risk factors for VaD. A higher educational level and engagement in social activities were identified as protective factors against both AD and VaD.

An epidemiological study of Alzheimer’s disease in elderly Mongolian and Han populations living in rural areas of Inner Mongolia

This study investigated the current status and distribution of Alzheimer's disease (AD) among Mongolian and Han individuals who were at least 55 years old and living in rural areas of Inner Mongolia. This study sought to provide basic epidemiological data to better understand and treat Alzheimer's disease. Individuals with AD who were at least 55 old and living in one of 27 communities and two settlements in Mongolia, took part in an AD epidemiological survey from June 2008 to June 2009. Stratified, multistage random-cluster sampling was used to analyze data. The first level of random-cluster sampling consisted of data collected from questionnaires and home-visit interviews of individuals living in four Qi (a county level administration region in Mongolia) and in one city in the Xilin Guole League. Data from individuals in four district offices and ten towns from the first level random-cluster formed the second level of random-cluster sampling. The final sample for this epidemiological investigation consisted of 9266 individuals. Analyses revealed that the prevalence rate of AD was 4.79% (SD=4.71%) in the combined Mongolian and Han populations of individuals at least 55 years old and living in rural areas of Inner Mongolia. The individual AD prevalence rates in the Mongolian and Han populations were 4.63% (SD=4.84%) and 4.89% (SD=4.60%), respectively. The AD prevalence rate for women was higher than for men (p<0.05). The AD prevalence rate for individuals aged 65 and older in the two combined populations was 8.06% (SD=8.55%); the rate in the Mongolian population was 7.81% (SD=8.38%) and 8.18% (SD=8.57%) in the Han population. Gender and age were risk factors for the development of AD (p<0.05) in both populations. 1) There was no significant difference in the AD prevalence rate between the Mongolian and Han populations consisting of individuals aged 55 and older, living in rural areas of Inner Mongolia. However, the AD prevalence rates in these populations were higher than the national average. 2) Gender and age were risk factors for the development of AD in the Mongolian and Han populations.

Alzheimer’s disease: ageing-related or age-related? New hypotheses from an old debate

The view that Alzheimer's disease (AD) is a fatal outcome of ageing prevails over the view that it mainly affects people aged 75-95. The former is based on the exponential increase in the incidence of AD with ageing, while the latter on AD prevalence rates. Both views share the idea that neurofibrillary degeneration (NFD) is secondary to the loading of β-protein (Aβ) and its more toxic species in nervous tissue that occurs with ageing in everybody, but is greater in people predisposed to AD. They differ in terms of the complexity attributed to the concept of neuronal vulnerability to Aβ. In the ageing-related hypothesis, it is seen as a phylogenetic characteristic of neurons that predisposes some of them to Aβ-dependent NFD, which spreads from the more vulnerable allocortex to the less vulnerable neocortex and accordingly causes memory decline progressing to dementia. To adapt this to the discontinuity of AD prevalence, it is necessary to see neuronal vulnerability as being modulated by additional ontogenetic factors that make some vulnerable neurons more or less sensitive to Aβ toxicity. This may give the Aβ/NFD relationship enough flexibility to explain the cognitive reserve of the oldest old and the phenotypical variability of AD, in particular why it is that the clinical onset of AD may be characterised by focal signs other than memory loss. Introducing this concept offers a new perspective of AD pathogenesis based on the role played by Aβ and related proteins in nerve cell selection during brain development and adult neurogenesis.

Prevalence rates for dementia and Alzheimer's disease in African Americans: 1992 versus 2001

Background This study compares age-specific and overall prevalence rates for dementia and Alzheimer's disease (AD) in two nonoverlapping, population-based cohorts of elderly African Americans in Indianapolis in 2001 and 1992. Methods We used a two-stage design. The first stage involves the Community Screening Interview for Dementia (CSI-D). The CSI-D scores are grouped into good, intermediate, and poor performance before selection for clinical assessment. Diagnoses were performed using standard criteria in a consensus diagnosis conference; clinicians were blind to performance groups. In 1992, interviewers visited randomly sampled addresses to enroll self-identified African Americans aged ≥65 years. Of 2582 eligible, 2212 enrolled (9.6% refused, and 4.7% were too sick). In 2001, Medicare rolls were used for African Americans aged >70 years. Of 4260 eligible, 1892 (44%) enrolled, 1999 (47%) refused, and the remainder did not participate for other reasons. Results The overall age-adjusted prevalence rate for dementia at age ≥70 years in 2001 was 7.45% (95 confidence interval [CI], 4.27–10.64), and in the 1992 cohort, this prevalence rate was 6.75% (95% CI, 5.77–7.74). The overall age-adjusted prevalence rate at age ≥70 years for AD in the 2001 cohort was 6.77% (95% CI, 3.65–9.90), and for the 1992 cohort, it was 5.47% (95% CI, 4.51–6.42). Rates for dementia and AD were not significantly different in the two cohorts (dementia, P = .3534; AD, P = .2649). Conclusions We found no differences in the prevalence rates of dementia and AD between 1992 and 2001, despite significant differences in medical history and medical treatment within these population-based cohorts of African American elderly.

The prevalence of dementia in an urban Turkish population.

A cross-sectional, population-based, 2-stage prevalence study was conducted in a sample of 1019 community-dwelling persons over the age of 70 years living in Istanbul. In the first phase, participants were screened with the Mini-Mental State Examination for evidence of cognitive impairment. In the second phase, 79% of those who screened positive (n = 322) and 9% of screen-negatives (n = 63) underwent a standardized diagnostic workup. Diagnosis of dementia and Alzheimer's disease (AD) was made according to established criteria. Ninety-three cases of dementia were identified, 58 of whom were diagnosed with probable AD. Based on these numbers, the prevalence rates of probable AD and dementia were calculated to be 11.0% (95% CI, 7.0% to 15.0%) and 20.0% (95% CI, 14.0% to 26.0%), respectively, in this population. Prevalence rates of dementia and AD in Istanbul, Turkey, are comparable with those seen in the Western world.

Cerebral amyloid beta protein deposits and other Alzheimer lesions in non-demented elderly east Africans.

There is little knowledge of the existence of Alzheimer disease (AD) or Alzheimer type of dementia in indigenous populations of developing countries. In an effort to evaluate this, we assessed the deposition of amyloid beta (A beta) protein and other lesions associated with AD in brains of elderly East Africans. Brain tissues were examined from 32 subjects, aged 45 to 83 years with no apparent neurological disease, who came to autopsy at two medical Institutions in Nairobi and Dar es Salaam. An age-matched sample from subjects who had died from similar causes in Cleveland was assessed in parallel. Of the 20 samples from Nairobi, 3 (15%) brains exhibited neocortical A beta deposits that varied from numerous diffuse to highly localized compact or neuritic plaques, many of which were also thioflavin S positive. Two of the cases had profound A beta deposition in the prefrontal and temporal cortices and one of these also exhibited moderate to severe cerebral amyloid angiopathy. Similarly, 2 of the 12 samples from Dar es Salaam exhibited diffuse and compact A beta deposits that were also predominantly reactive for the longer A beta 42 species compared to A beta 40. We also noted that A beta plaques were variably immunoreactive for amyloid associated proteins, apolipoprotein E, serum amyloid P and complement C3. Tau protein reactive neurofibrillary tangles (NFT) were also evident in the hippocampus of 4 subjects. By comparison, 4 (20%) of the 20 samples from randomly selected autopsies performed in Cleveland showed A beta deposits within diffuse and compact parenchymal plaques and the vasculature. These observations suggest A beta deposition and some NFT in brains of non-demented East Africans are qualitatively and quantitatively similar to that in age-matched elderly controls from Cleveland. While our small scale study does not document similar prevalence rates of preclinical AD, it suggests that elderly East Africans are unlikely to escape AD as it is known in developed countries.

Sources of variability in prevalence rates of Alzheimer's disease.

To investigate potential methodological reasons for the differences in published Alzheimer's disease (AD) prevalence rates. Studies reporting prevalence rates of AD have been published worldwide. These rates differ considerably, but may greatly reflect methodological differences. All studies published between 1984 and 1993 that reported age-specific AD rates and sample sizes were included. Logistic regression identified variables that contribute to the variation in rates. Estimates of extrabinomial variation were also calculated. Studies characterized by the following features yielded significantly higher rates: inclusion of mild cases, use of laboratory studies, ascertainment of a sample rather than the total population, inclusion of both urban and rural populations, non-use of computerized tomography (CT) scans, non-use of the Hachinski Ischemic Score, and no adjustment for false negatives. The odds of having AD increased 18% for every year of age. The variation in the age-specific prevalence rates of AD was approximately 15 times that expected by sampling variation. However, approximately 76% of this excess variation in rates could be accounted for by methodological differences. After accounting for age, much of the variability in prevalence rates of AD in the published literature may be explained by differences in methodology. Some unexplained variation in prevalence rates, however, still remains.