Prevalence of dementia in rural China: impact of age, gender and education

OBJECTIVE: To determine the prevalence of dementia and Alzheimer's disease (AD) in rural China. METHODS: A cross-sectional study was conducted within a cohort of adults older than 50 years of age in Linxian County, China. A Chinese version of the Mini-Mental State Examination (CMMSE) was used to screen cases of possible dementia. Three different cutoff points on CMMSE were applied depending on the participant's level of education. The participants then were given psychiatric interviews, medical and neurological examinations, and psychometric tests to ascertain the clinical diagnoses of dementia and AD. RESULTS: Among the 16,095 participants, 5.26% were screened positive with 374 diagnosed as having dementia. Among them, AD accounted for 80.5%. The adjusted prevalence rates were 0.33%, 0.89%, 3.43%, and 8.19% in people in age groups 50-54, 55-64, 65-74, and 75 and above, respectively. The prevalence of AD correlated with the participant's level of education, and was 2.61%, 0.94%, and 0.56% in the illiterate group, in the primary school group, and in the middle school or higher group, respectively. Adjusted by education levels a higher prevalence in women was observed in the illiterate group. CONCLUSIONS: The prevalence of dementia in this population is similar to that reported from other areas in mainland China and Taiwan with aging being a significant risk factor. After controlling for age, being a female and having received less number of years of education were associated with an higher prevalence of AD.     

High prevalence of mild cognitive impairment and Alzheimer's disease in arabic villages in northern Israel: impact of gender and education

The prevalence of mild cognitive impairment (MCI) and Alzheimer's disease (AD) have not been well been studied in Arab populations. In a door-to-door study of all residents aged ≥ 65 years in Wadi-Ara, an Arab community in northern Israel, we estimated the prevalence of AD, MCI, and the risk of conversion to AD. Subjects were classified as cognitively normal, MCI, AD, or other based on neurological and cognitive examination (in Arabic). MCI subjects were re-examined (interval ≥ 1 year) to determine conversion to AD and contributions of age, gender, and education to the probability of conversion. Of the 944 participants (96.6% of those approached; 49.4% men), 92 (9.8%) had AD. An unusually high prevalence of MCI (n = 303, 32.1%) was observed. Since the majority of women (77.2%) had no schooling, we estimated the effect of gender on the risk of AD and MCI among subjects without schooling and of school years among men. Among subjects with no schooling (n = 452), age (p = 0.02) and female gender (p < 0.0001) were significant predictors of AD, whereas risk of MCI increased only with age (p = 0.0001). Among men (n = 318), age increased the risk (p < 0.0001), school years reduced the risk of AD (p = 0.039) and similarly for MCI [age (p = 0.0001); school years (p = 0.0007)]. Age (p = 0.013), but not gender or school years, was a significant predictor of conversion from MCI to AD (annual rate 5.7%). The prevalence of MCI and AD are unusually high in Wadi Ara, while the rate of conversion from MCI to AD is low. Yet unidentified genetic factors might underlie this observation.     

The impact of dementia, age and sex on category fluency: greater deficits in women with Alzheimer's disease

A category specific effect in naming tasks has been reported in patients with Alzheimer's dementia. Nonetheless, naming tasks are frequently affected by methodological problems, e.g., ceiling effects for controls and "nuisance variables" that may confound results. Semantic fluency tasks could help to address some of these methodological difficulties, because they are not prone to producing ceiling effects and are less influenced by nuisance variables. One hundred and thirty-three participants (61 patients with probable AD; and 72 controls: 36 young and 36 elderly) were evaluated with semantic fluency tasks in 14 semantic categories. Category fluency was affected both by dementia and by age: while in nonliving-thing categories there were differences among the three groups, in living thing categories larger lexical categories produced bigger differences among groups. Sex differences in fluency emerged, but these were moderated both by age and by pathology. In particular, fluency was smaller in female than male Alzheimer patients for almost every subcategory.     

Cerebral glucose metabolic patterns in Alzheimer's disease. Effect of gender and age at dementia onset

No previous study of Alzheimer's disease has, to our knowledge, assessed the effect of both age at dementia onset and gender on cerebral glucose metabolic patterns. To this end, we used positron emission tomography (fludeoxyglucose F 18 method) to study 24 patients with clinical diagnoses of probable Alzheimer's disease. Comparisons of the 13 patients with early-onset dementia (less than 65 years of age) with the 11 patients with late-onset dementia (greater than 65 years of age) revealed significantly lower left parietal metabolic ratios (left posterior parietal region divided by the hemispheric average) in the early-onset group. The metabolic ratio of posterior parietal cortex divided by the relatively disease-stable average of caudate and thalamus also separated patients with early-onset dementia from those with late-onset dementia, but not men from women. Further comparisons between sexes showed that, in all brain regions studied, the 9 postmenopausal women had higher nonweighted mean metabolic rates than the 15 men from the same age group, with hemispheric sex differences of 9% on the right and 7% on the left. These results demonstrate decreased parietal ratios in early-onset dementia of Alzheimer's disease, independent of a gender effect.     

Alzheimer's disease and vascular dementia in developing countries: prevalence, management, and risk factors

Despite mortality due to communicable diseases, poverty, and human conflicts, dementia incidence is destined to increase in the developing world in tandem with the ageing population. Current data from developing countries suggest that age-adjusted dementia prevalence estimates in 65 year olds are high (>or=5%) in certain Asian and Latin American countries, but consistently low (1-3%) in India and sub-Saharan Africa; Alzheimer's disease accounts for 60% whereas vascular dementia accounts for approximately 30% of the prevalence. Early-onset familial forms of dementia with single-gene defects occur in Latin America, Asia, and Africa. Illiteracy remains a risk factor for dementia. The APOE epsilon4 allele does not influence dementia progression in sub-Saharan Africans. Vascular factors, such as hypertension and type 2 diabetes, are likely to increase the burden of dementia. Use of traditional diets and medicinal plant extracts might aid prevention and treatment. Dementia costs in developing countries are estimated to be US$73 billion yearly, but care demands social protection, which seems scarce in these regions.     

The prevalence, assessment and associations of falls in dementia with Lewy bodies and Alzheimer's disease

Falls were assessed for 3 months using a daily fall diary in 65 (30 dementia with Lewy bodies, DLB; 35 Alzheimer's disease, AD) dementia patients from a case register, diagnosed using operationalised clinical criteria, with established accuracy against post-mortem. Multiple falls (>5) occurred in 37% of DLB patients and 6% of those with AD, often resulting in injury. None of the standard risk assessment tools identified fallers, but they did identify multiple fallers. More detailed evaluation methods examining gait patterns, sway and neurovascular instability were not helpful. Multiple falls were associated with DLB, parkinsonism, previous falls, greater impairment of activities of daily living and older age. Falls are particularly common in DLB sufferers and may aid diagnosis. Treatment studies evaluating fall reduction strategies are a priority.     

The prevalence of dementia in old age

The risk of manifestation of dementia increases as the population grows older. The prevalence of dementia increases from 0.7% in age group 60-64 years to 38.8% in age group 90-94 years. Over 60, the prevalence rate doubles every 5.1 years. The most common types of dementia are Alzheimer's dementia and vascular dementia.     

Economic impact of dementia in developing countries: an evaluation of Alzheimer-type dementia in Shanghai, China

The main objective of this study was to assess the economic cost of Alzheimer's disease (AD) in Shanghai, China, as a pilot study for future evaluations. Sixty-seven patients with AD were interviewed, and the information of the AD-related cost and resources used was collected from October 2005 to September 2006. By retrospective analysis, annual costs were calculated and expressed in Chinese renminbi (RMB). Direct cost per patient per year averaged approximately 8,432 RMB (1,058 USD), indirect cost per patient per year was 10,568 RMB (1,326 USD), and annual costs were 19,001 RMB (2,384 USD) per patient per year in this investigation. Total cost was significantly associated with the degree of severity including cognitive function (MMSE) and activity of daily living (ADL). With the increase in the number of persons at risk for developing AD, the economic burden of AD patients in China is significantly heavy.     

Behaviour in frontotemporal dementia, Alzheimer's disease and vascular dementia

OBJECTIVES: The study aimed to increase understanding of behavioural changes in frontotemporal dementia (FTD) and identify features that best differentiate FTD from Alzheimer's disease (AD) and cerebrovascular dementia (CvD). METHODS: A semi-structured questionnaire was administered to carers of 30 FTD, 75 AD and 34 CvD patients. RESULTS: Behavioural changes that strongly discriminated FTD from AD and to a lesser extent CvD were loss of emotions and insight, selfishness, disinhibition, personal neglect, gluttony and sweet food preference, wandering, motor and verbal stereotypies, loss of pain, echolalia and mutism. Irritability, hyposexuality and hypersomnia did not discriminate. Emotional, eating and stereotyped behaviours correctly classified 95% of patients using regression analysis. CONCLUSIONS: Behavioural characteristics accurately differentiate FTD from AD and CvD. The findings highlight the particular importance of affective change in FTD, and underline the role of the frontotemporal lobes in emotion.     

First episodes of behavioral symptoms in Alzheimer's disease patients at age 90 and over, and early-onset Alzheimer's disease: comparison with senile dementia of Alzheimer's type

We evaluated dementia symptoms to clarify the character of dementia with Alzheimer's disease (AD) observed in the oldest old patients and that of dementia with early-onset AD. Subjects were consecutive AD inpatients admitted for the first time at age of 90 years and over because of behavioral symptoms (demented nonagenarian group: D90G; n=18) and those with 24 consecutive inpatients with AD with early-onset (EOG). The Gottfries, Brane and Steen's scale and the Dementia Behavior Disturbance scale were used to evaluate the symptoms and troublesome behaviors. The scores of these scales in D90G and in EOG were compared with those of 26 sex distribution-, severity of dementia-, and disease duration-matched inpatients with AD with late-onset (LOG). Compared with LOG, wakefulness was more impaired and waking up at night was more frequent in D90G, while memory, orientation and inappropriate behaviors were more severe in EOG. These results suggest that the clinical features of dementia in EOG were quantitatively different from those of LOG. In contrast, the clinical feature of dementia of D90G were sleep-wake pattern disturbance and were qualitatively different from those of LOG.     

The characterisation and impact of 'fluctuating' cognition in dementia with Lewy bodies and Alzheimer's disease

BACKGROUND: Case reports and clinical observations suggest that fluctuating cognition (FC) is common in all the major dementias, particularly dementia with Lewy bodies (DLB) where it is one of three core clinical diagnostic features. The purpose of this study was to characterise FC and determine its impact upon activities of daily living. METHODS: Forty matched subjects (15 DLB, 15 AD, 10 elderly controls) were assessed using the activities of daily living scale (ADLD), the cognitive drug research (CDR) computerised neuropsychological test battery and a semi-standardised assessment of FC. The CDR battery was completed three times across a 1-week period, to evaluate variability in attention, visuospatial ability, working memory and delayed recall. RESULTS: There was a strong positive correlation between clinical FC scores and total mean ADLD. Measures of cognitive variability also demonstrated strong significant correlations with independent clinical severity ratings of FC across several cognitive domains. These associations were most powerful between attentional measures and clinical FC ratings. CONCLUSIONS: Although attention is the cognitive domain which fluctuates most markedly, other cognitive domains are also affected. FC also has a significant independent impact on activities of daily living.     

Vascular dementia: atherosclerosis, cognition and Alzheimer's disease

Both Alzheimer's disease type pathology (neuritic plaques and neurofibrillary tangles) and evidence of atherosclerosis and infarcts are common in autopsy specimens from the brains of patients enrolled in longitudinal prospective cohorts; the relative contribution of each of these to overall cognitive function is unclear. In addition whether each of these two forms of brain pathology can accelerate the appearance of the other is also unclear. In this paper we examine the relationship among Alzheimer's brain pathology, cerebral infarcts and cerebral atherosclerosis. We conclude that each is an independent predictor of dementia. Moreover we do not find that atherosclerosis increases Alzheimer's type brain pathology or vice versa.     

Mixed dementia: Alzheimer's and cerebrovascular disease

"Mixed dementia" is traditionally defined as Alzheimer's disease with cerebrovascular disease (CVD). Because the risks of both neurodegenerative dementias and cerebrovascular disease increase with age, the mixed dementias are likely the most common. In practice, patients with mixed dementia are diagnosed by one of two routes: Either they have evidence of a neurodegenerative dementia and CVD at the outset, or, they have a classical neurodegenerative presentation but are found to have ischemic lesions by neuroimaging. These facts have implications for the development of evidence-based diagnostic criteria.     

The effects of behavioral and psychological symptoms on caregiver burden in frontotemporal dementia,Lewy body dementia,and Alzheimer's disease: clinical experience in China

Background and aims: Caregivers of individuals with neurodegenerative diseases, including frontotemporal dementia (FTD), Lewy body dementia (DLB), and Alzheimer's disease (AD), experience high levels of psychological and physical stress, likely due to behavioral and psychological symptoms of dementia (BPSD). This study is the first to simultaneously evaluate the effects of BPSD on caregiver burden in these three types of dementia.

Method: A total of 214 dementia patients, including probable FTD (n = 82), DLB (n = 22), and AD (n = 110), as well as their primary caregivers, were assessed using psychological inventories and cognitive evaluation. The FTD group was further divided into the three established clinical variants: behavioral variant frontotemporal dementia (bvFTD, n = 51), non-fluent variant primary progressive aphasia (nfvPPA, n = 15), and semantic variant primary progressive aphasia (svPPA, n = 16). Cognitive impairment and neuropsychiatric symptoms were assessed using the Mini Mental State Examination, Montreal Cognitive Assessment, Clock Drawing Test, and Neuropsychiatric Inventory (NPI), respectively. Caregiver burden was assessed using the Zarit Burden Inventory (ZBI).

Results: FTD patients had higher NPI and ZBI scores than DLB and AD patients, whose scores were similar. Logistic regression analysis revealed that the factors influencing caregiver burden for each group were: FTD: total NPI scores, agitation, and aberrant motor behavior; bvFTD: total NPI scores; DLB: total NPI scores; and AD: total NPI scores, onset age, apathy, and ADL. Caregivers of bvFTD patients had the highest levels of burden, which were significantly greater than for caregivers of nfvPPA, svPPA, DLB, and AD patients.

Conclusion: BPSD was highly correlated with emotional burden in caregivers of FTD, DLB, and AD patients. The highest burden was observed in bvFTD caregivers.     

The progression of cognitive impairment in dementia with Lewy bodies, vascular dementia and Alzheimer's disease

BACKGROUND: Little is known about the rate of progression or associations of cognitive impairment in dementia with Lewy bodies (DLB), or the associations of accelerated decline. METHOD: Dementia patients from a case register were evaluated at baseline and 1 year follow-up using the Cambridge Assessment for Mental Disorders in the Elderly, section B (CAMCOG) and the Mini-Mental State Examination (MMSE) to determine the rate of cognitive decline. Operationalized clinical diagnoses were applied (NINCDS ADRDA for Alzheimer's disease (AD), NINCDS AIRENS for vascular dementia (VaD) and consensus criteria for DLB). RESULTS: One hundred and ninety-three patients completed annual MMSE schedules (AD, 101; DLB, 64; VaD, 38), of whom 154 completed the CAMCOG. The magnitude of cognitive decline (MMSE, 4-5 points; CAMCOG, 12-14 points) was similar in each of the dementias. The strongest predictor of accelerated cognitive decline in DLB was the apolipoprotein E4 allele (17.5 vs 8.3 points decline on the CAMCOG). CONCLUSION: Over 1 year, DLB, VaD and AD patients had similar rates of cognitive decline overall. Apolipoprotein E4 may be an important predictor of more rapid decline in DLB.     

The prevalence of apoE-ε4 in Alzheimer's disease is age dependent

The ε4 allele of apolipoprotein E is a risk factor forAlzheimer's disease. However, other yet unidentified factors might beinvolved. It has been suggested that the ε4 allele might be relatively less relevant in Alzheimer's disease with onset before age60 and after age 80. The aim was to evaluate the association of theε4 allele with Alzheimer's disease across a wide range of ages atonset. 156 patients with age at onset between 46 and 89 and 120 cognitively unimpared subjects aged 53 to 89 as controls were studied.Age at onset in the cases and age in the controls were stratified intosix groups (60 and younger, 60 to 64, 65to 69, 70 to 74, 75 to 79, and80 and older). Multivariable sex adjusted probit regression analysiswas used to model ε4 prevalences in cases and controls across age.The sex adjusted relation of ε4 with age in controls was slightlynegative with prevalence of 0.16 in the youngest and 0.09 in the oldestage groups. The sex adjusted relation in cases with Alzheimer'sdisease had a bell shaped curve with prevalence of 0.23 in the youngestage group, rising to 0.54 and 0.51 in the age groups 65 to 69 and 70 to74, and decreasing to 0.12 in the oldest age group. It is concludedthat the relation of the ε4 allele with Alzheimer's disease is agedependent, indicating that other risk factors might be relevant in theyounger and older ages.