Epidemiologic and genetic studies of dementia of the alzheimer type in japan

Global Prevalence of Young-Onset Dementia: A Systematic Review and Meta-analysis

Importance

Reliable prevalence estimates are lacking for young-onset dementia (YOD), in which symptoms of dementia start before the age of 65 years. Such estimates are needed for policy makers to organize appropriate health care.

Objective

To determine the global prevalence of YOD.

Data Sources

The PubMed, Embase, CINAHL, and PsycInfo databases were systematically searched for population-based studies on the prevalence of YOD published between January 1, 1990, and March 31, 2020.

Study Selection

Studies containing data on the prevalence of dementia in individuals younger than 65 years were screened by 2 researchers for inclusion in a systematic review and meta-analysis.

Data Extraction and Synthesis

Prevalence estimates on 5-year age bands, from 30 to 34 years to 60 to 64 years, were extracted. Random-effects meta-analyses were conducted to pool prevalence estimates. Results were age standardized for the World Standard Population. Heterogeneity was assessed by subgroup analyses for sex, dementia subtype, study design, and economic status based on the World Bank classification and by meta-regression.

Main Outcomes and Measures

Prevalence estimates of YOD for 5-year age bands.

Results

A total of 95 unique studies were included in this systematic review, of which 74 with 2 760 379 unique patients were also included in 5-year age band meta-analyses. Studies were mostly conducted in Europe and in older groups in Asia, North America, and Oceania. Age-standardized prevalence estimates increased from 1.1 per 100 000 population in the group aged 30 to 34 years to 77.4 per 100 000 population in the group aged 60 to 64 years. This gives an overall global age-standardized prevalence of 119.0 per 100 000 population in the age range of 30 to 64 years, corresponding to 3.9 million people aged 30 to 64 years living with YOD in the world. Subgroup analyses showed prevalence between men and women to be similar (crude estimates for men, 216.5 per 100 000 population; for women, 293.1 per 100 000 population), whereas prevalence was lower in high-income countries (crude estimate, 663.9 per 100 000 population) compared with upper-middle-income (crude estimate, 1873.6 per 100 000 population) and lower-middle-income (crude estimate, 764.2 per 100 000 population) countries. Meta-regression showed that age range (P < .001), sample size (P < .001), and study methodology (P = .02) significantly influenced heterogeneity between studies.

Conclusions and Relevance

This systematic review and meta-analysis found an age-standardized prevalence of YOD of 119.0 per 100 000 population, although estimates of the prevalence in low-income countries and younger age ranges remain scarce. These results should help policy makers organize sufficient health care for this subgroup of individuals with dementia.

Study Registration

PROSPERO CRD42019119288.

Effects of a lifestyle development program designed to reduce the risk factors for cognitive decline on the mental health of elderly individuals

BACKGROUND

The incidence of Alzheimer's disease (AD) along with depression is high in the elderly. In the present study, a program that allows the elderly individuals to voluntarily manage and develop lifestyles that may reduce the risk factors for cognitive decline was applied to the participants to evaluate its effect on the mental health of these individuals.

METHODS

The participants were randomly assigned to an intervention group and a control group. The program was conducted during 7 months in the intervention group, and it had seven times of group activities, performed once a month for about 1 h, and individual activities to reduce the risk factors for cognitive decline, performed every day. To evaluate the effects of the program on the mental health of the participants, the Geriatric Depression Scale (GDS) and Philadelphia Geriatric Center Morale Scale (PGC) were used. These two scales were applied twice to the intervention and control groups.

RESULTS

The GDS score revealed no change in the score in the intervention group before and after the 7-month program implementation; however, in the control group, the score was significantly higher after program implementation than that before. The PGC score revealed no change in the intervention group before and after 7-month program implementation; however, in the control group, the score was significantly lower after program implementation than that before. Additionally, it revealed no change in the GDS score in the depression-prone control group before and after 7-month program implementation; however, in the depression-prone intervention group, the GDS score was significantly lower after program implementation than that before.

CONCLUSIONS

The intervention program that allows the elderly individuals to voluntarily manage and develop lifestyles that may reduce the risk factors for cognitive decline is expected to maintain mental health in elderly individuals.

The Effectiveness of Training Programs on the Fidelity of Neuropsychological Tests

Background

There will probably be an exponential increase in the number of seniors suffering from dementia, as aging is the greatest risk factor for this disease. Therefore, neuropsychological tests to assessing dementia are likely to play an increasingly important role for medical services in Japan. This study developed and evaluated the usefulness of a training program on neuropsychological tests aimed at promoting the understanding of testers with regard to the cognitive functions and communication required in the neuropsychological testing process.

Methods

The subjects of this study comprised 20 individuals engaged in administrating neuropsychological tests at the Japan-Multidomain Intervention Trial for Prevention of Dementia in Older Adults with Diabetes. A four-hour training session was held. The first part of the training program focused on "cognitive functions and communication;" the second addressed "neuropsychological tests." As the main evaluation criteria, a fidelity checklist was created with 14 items designed to measure success or failure with regard to important and easily mistakable aspects of implementing each neuropsychological test. They were conducted three times: before, immediately after, and six months after the training.

Results

The main effect of time was significant for the "fidelity" score. The effect size was large at η² = 0.69. A simple main effect test using the Bonferroni method revealed significant differences between the pre-training and post-training values and between the pre-training and six-month point values. However, no significant differences were found in self-efficacy scores before, immediately after, and six months after the training.

Conclusion

This outcome indicates that the fidelity of the subjects to neuropsychological tests increased as a result of the training program, and that this improvement was maintained through the six-month period following the program. Moreover, the large effect size suggests that the training program may be effective in facilitating the mastery of neuropsychological tests in testers.

Secular Trends in Dementia Prevalence and Incidence Worldwide: A Systematic Review

BACKGROUND

Time trends for dementia prevalence and incidence rates have been reported over the past seven decades in different countries and some have reported a decline.

OBJECTIVE

To undertake a systematic review to critically appraise and provide an evidence-based summary of the magnitude and direction of the global changes in dementia prevalence and incidence across time.

METHODS

Medline, EMBASE, and PsychINFO were searched for studies focused on secular trends in dementia prevalence and/or incidence until 18 December 2017. In total, 10,992 articles were identified and 43 retained.

RESULTS

Overall, prevalence rates are largely increasing (evidence primarily from record-based surveys and cohort studies in Japan, Canada, and France) or have remained stable (evidence primarily from cohort studies in Sweden, Spain and China). A significant decline in prevalence has however been reported in more recent studies (i.e., from 2010 onwards) from Europe (e.g., UK and Sweden) and the USA. Incidence rates have generally remained stable or decreased in China, Canada, France, Germany, Denmark, Sweden, the Netherlands, UK, and USA. An increase has only been reported in five countries: Italy, Japan, Wales, Germany, and the Netherlands. Only one study reported findings (stability in incidence) from a low and middle-income country using data from Nigeria.

CONCLUSIONS

The evidence on secular trends in the prevalence and incidence of dementia is mixed including contradictory findings using different (and in some cases the same) datasets in some countries (e.g., the USA, UK, and Sweden). This making it difficult to draw concrete conclusions. However, declining trends recently observed in some high-income Western countries in the most recent two decades including the UK, USA, and Sweden are encouraging. Updated dementia prevalence and incidence estimates will inform public health and financial planning as well as development of prevention strategies.

Clinical and neuroimaging characterization of Chinese dementia patients with PSEN1 and PSEN2 mutations

BACKGROUND

Alzheimer's disease (AD) and frontotemporal dementia (FTD) are two common forms of primary neurodegenerative dementia. Mutations in 3 genes (PSEN1, PSEN2, and APP) have been identified in patients with early-onset AD.

METHODS

We performed gene sequencing in PSEN1, PSEN2, and APP in 61 AD and 35 FTD Chinese patients. Amyloid load using (11)C-labeled Pittsburgh compound B ((11)C-PIB) positron emission tomography (PET) and cerebral glucose metabolism using (18)F-fludeoxyglucose PET were evaluated in patients carrying mutations.

RESULTS

We identified 1 known pathogenic PSEN1 (p.His163Arg, c.488A>G) mutation and 3 novel PSEN2 mutations in 6 patients. The novel mutation PSEN2 (p.His169Asn, c.505C>A) was identified in 1 patient with familial late-onset AD and in 1 sporadic FTD patient. The PSEN2 (p.Val214Leu, c.640G>T; p.Lys82Arg, c.245A>G) mutations were identified in 2 early-onset AD patients and 1 early-onset AD patient, respectively. Three patients with PSEN2 mutations were observed to have PIB retention on the cortex and striatum. One patient with the FTD phenotype was not observed to have PIB retention.

CONCLUSION

PSEN2 mutations are common in the Chinese Han population with a history of AD and FTD. Pathogenic mutations or risk variants in the PSEN2 gene can influence both FTD and AD phenotypic traits and show variations in neuroimaging characterization.

Prevalence and clinical predictors of cognitive impairment in individuals aged 80 years and older in rural China

AIMS

The aim of this study was to estimate the prevalence of cognitive impairment (CI) in individuals aged 80 years and over in rural China and to analyze the associated risk factors.

METHODS

We conducted a two-phase door-to-door survey of a population in rural Ji County (China). The reference population consisted of individuals aged 80 years or older. A total of 723 individuals were interviewed in their homes, and demographic variables and comorbidities were recorded. Diagnoses were divided into the following 3 categories: normal cognitive function, cognitive impairment no dementia (CIND), and dementia. The odds ratio for each risk factor was calculated by logistic regression analysis.

RESULTS

The prevalence of CI among individuals aged 80 years and older was 73.2% (47.4% CIND and 25.7% dementia). The risk of CI decreased with a higher level of education and a higher level of social involvement. The risk of CI was higher in females than in males and among people with a history of stroke (p < 0.01).

CONCLUSIONS

The observed raw prevalence of CI was 73.2%. Female gender and a history of a previous stroke increased the risk of CI, while a higher educational level and engagement in social activities reduced the risk of CI.

The relationship between the diagnosis method of neuronal dysfunction (DIMENSION) and brain pathology in the early stages of Alzheimer's disease

OBJECTIVES

To examine whether the diagnosis method of neuronal dysfunction (DIMENSION), a new electroencephalogram (EEG) analysis method, reflected pathological changes in the early stages of Alzheimer's disease (AD), we conducted a comparative study of cerebrospinal fluid markers and single-photon emission computed tomography.

METHODS

Subjects cincluded 32 patients in the early stages of AD with a Mini-Mental State Examination score ≥24 (14 men, 18 women; mean age, 77.3 ± 9.2 years). Cerebrospinal fluid samples were collected from AD patients, and cerebrospinal fluid levels of phosphorylated tau protein (p-tau) 181 and amyloid β (Aβ) 42 were measured with sandwich ELISA. EEG recordings were performed for 5 min with the subjects awake in a resting state with their eyes closed. Then, the mean value of the EEG alpha dipolarity (Dα) and the standard deviation of the EEG alpha dipolarity (Dσ) were calculated with DIMENSION. Single-photon emission computed tomography analyses were also performed for comparison with DIMENSION measures.

RESULTS

Patients with parietal hypoperfusion had significantly increasing p-tau181, decreasing Dα, and increasing Dσ. In addition, there was a negative correlation between Dα and p-tau181, p-tau181/Aβ42, and a positive correlation between Dσ and p-tau181/Aβ42.

CONCLUSION

Dα and Dσ were related to cerebral hypoperfusion and p-tau181/Aβ42. DIMENSION was able to detect changes in the early-stage Alzheimer's brain, suggesting that it is possibility as a useful examination for early-stage AD with a difficult discrimination in clinical conditions. Moreover, EEG measurement is a quick and easy diagnostic test and is useful for repeated examinations.

Genetic polymorphism in exon 2 of cathepsin D is not associated with vascular dementia

BACKGROUND

Cathepsin D, the most abundant lysosomal and endosomal aspartyl protease, shows beta and gamma secretase activity in vitro by cleaving the amyloid precursor protein (APP) into amyloid beta protein (Aβ). Polymorphism at position 224, C224T, on exon 2 of cathepsin D gene (CTSD) has been associated with an increased risk for Alzheimer's disease (AD) by some investigators, but there have been contrary findings by others. However, an association between CTSD polymorphism and vascular dementia (VaD) has not been reported thus far.

OBJECTIVE

To investigate whether a polymorphism at CTSD C224T is associated with VaD in the Korean population.

METHODS

We compared the genotype and allele frequencies at this polymorphism site in clinically assessed 162 VaD patients with those in 197 healthy Koreans.

RESULTS AND CONCLUSION

The major genotype frequency at CTSD C224T in normal controls was higher in the Asian population than in various European populations. Our study does not show a significant difference in genotype (P=0.3071) and allele (P=0.2291) frequencies of CTSD C224T between VaD and normal controls. This was the first genetic association study of CTSD in a VaD population.

[Early diagnostic biomarker for Alzheimer's disease now and in the future]

Alzheimer's disease is thought to be "common disease". It is expected that new biological diagnostic marker will be discovered for Alzheimer's disease. There are two roles in diagnostic biomarker for AD.: one is a screening and the other one is to help definite diagnosis for AD. Simple screening method using touch panel type computer (Forgetfulness consultation program) is most useful of screening tools and phosphorylated tau protein in cerebrospinal fluid is highly appreciated as a diagnostic biomarker to help definite diagnosis. Serum WGA binding transferrin in AD is significantly higher than that in controls and high levels of it proceed increased levels of amyloid beta protein. Serum WGA binding transferrin may be useful for early diagnostic biomarker in serum.

Effect of aromatherapy on patients with Alzheimer's disease

OBJECTIVE

Recently, the importance of non-pharmacological therapies for dementia has come to the fore. In the present study, we examined the curative effects of aromatherapy in dementia in 28 elderly people, 17 of whom had Alzheimer's disease (AD).

METHODS

After a control period of 28 days, aromatherapy was performed over the following 28 days, with a wash out period of another 28 days. Aromatherapy consisted of the use of rosemary and lemon essential oils in the morning, and lavender and orange in the evening. To determine the effects of aromatherapy, patients were evaluated using the Japanese version of the Gottfries, Brane, Steen scale (GBSS-J), Functional Assessment Staging of Alzheimer's disease (FAST), a revised version of Hasegawa's Dementia Scale (HDS-R), and the Touch Panel-type Dementia Assessment Scale (TDAS) four times: before the control period, after the control period, after aromatherapy, and after the washout period.

RESULTS

All patients showed significant improvement in personal orientation related to cognitive function on both the GBSS-J and TDAS after therapy. In particular, patients with AD showed significant improvement in total TDAS scores. Result of routine laboratory tests showed no significant changes, suggesting that there were no side-effects associated with the use of aromatherapy. Results from Zarit's score showed no significant changes, suggesting that caregivers had no effect on the improved patient scores seen in the other tests.

CONCLUSIONS

In conclusion, we found aromatherapy an efficacious non-pharmacological therapy for dementia. Aromatherapy may have some potential for improving cognitive function, especially in AD patients.

Lack of association between apolipoprotein E polymorphism and vascular dementia in Koreans

To investigate an association of vascular dementia (VD) with the apolipoprotein E (APOE) polymorphism, the APOE polymorphism of 100 VD patients, 100 age- and gender-matched Alzheimer disease (AD) patients, and 200 age- and gender-matched nondemented control (NC) subjects was genotyped. The distribution of APOE polymorphism was compared. Neither the APOE epsilon4 allele nor the APOE epsilon2 allele was more prevalent in the VD patients compared with the NC subjects (P > .1 by the chi 2 test), which was the case when both men and women were analyzed separately (P > .1 by the chi2 test) and when young patients (75 years old or less) and old patients (more than 75 years old) were analyzed separately (P > .1 by the chi2 test). The estimated statistical power was over 0.80 when the odds ratios (OR) for VD conferred to the APOE epsilon4 are assumed to be higher than 2.2 and the type I error probability is set at 0.05, which is much higher than the power of the previous studies on the VD/APOE association. In conclusion, the results suggested that APOE epsilon4 allele does not confer the risk for VD, and even if it does, it does so very modestly.

Absence of association between codon 129 and 219 polymorphisms of the prion protein gene and vascular dementia

BACKGROUND

Polymorphisms of the prion protein gene (PRNP) are known to cause a strong susceptibility to the occurrence of prion diseases, such as Creutzfeldt-Jakob disease, and might be associated with other neurodegenerative disorders. However, an association between PRNP polymorphisms and vascular dementia (VaD) has not been reported thus far.

OBJECTIVE

To investigate whether the PRNP polymorphisms are associated with an increased risk for developing VaD in the Korean population.

METHODS

We compared the genotype, allele and haplotype frequencies of PRNP polymorphisms in 160 VaD patients with those in 236 healthy Koreans.

RESULTS AND CONCLUSION

Codon 129 (M129V) and 219 (Q219K) polymorphisms in Korean VaD patients were found in the open reading frame of PRNP. Our study shows that there is no significant difference in the genotype, allele and haplotype frequencies of PRNP codon 129 and 219 polymorphisms between Korean VaD patients and normal controls. This was the first genetic association study of the polymorphisms of PRNP with VaD.

Elevated interleukin-6 levels in cerebrospinal fluid of vascular dementia patients

OBJECTIVES

To investigate a possible implication of inflammatory processes in the development of dementia in cerebrovascular disease.

PATIENTS AND METHODS

We examined the levels of interleukin-6 (IL-6) in the cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD) (n = 26), ischemic cerebrovascular disease without dementia (CVD) (n = 11), vascular dementia (VD) (n = 11), and other neurological disorders (n = 21) using sensitive enzyme-linked immunosorbent assay.

RESULTS

The CSF concentrations of IL-6 were significantly elevated in patients with VD compared with those of patients with AD or CVD.

CONCLUSION

The CSF IL-6 levels are increased in patients with VD, suggesting that inflammatory mechanisms may be involved in the development of cognitive decline in some patients with cerebrovascular disease. CSF IL-6 may be a biological marker for dementia in cerebrovascular disease.

Apolipoprotein E in Taiwan Chinese patients with dementia

To clarify whether Alzheimer's disease (AD) and vascular dementia (VaD) share the same risk factors in Taiwan Chinese patients. Using the criteria of the NINCDS- ADRDA and NINDS-AIREN, 154 AD patients, 30 VaD patients, and 112 controls were enrolled. Their apolipoprotein E (ApoE) genes, extracted from peripheral blood leukocytes, were analyzed. The epsilon4 allele frequency was significantly higher in AD patients than in the control group. The odds ratio of carrying at least one copy of the epsilon4 allele in AD patients is 2.7 compared with control subjects. There was no significant difference between the VaD patients and the control subjects in their ApoE epsilon4 or epsilon2 allele frequency. The present study demonstrates a strong association between the ApoE epsilon4 allele and AD, but not between the ApoE epsilon4 allele and VaD. This suggests that AD and VaD do not share the same pathogenesis and deserve further investigation.

The prevalence of dementia in older people in an urban population of Korea: the Seoul study

OBJECTIVES

To estimate prevalence of dementia and its subtypes in older people in Seoul, a metropolitan area of Korea, and compare these findings with estimates reported for other populations.

DESIGN

The study employed a two-stage design for case identification. Initially, the Mini-Mental State Examination in the Korean version (MMSE-KC) of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) assessment packet was administered to all participants. Two hundred seventeen persons sampled from three levels of performance on MMSE-KC underwent the second-stage clinical evaluation based on the Korean Version of the CERAD assessment packet.

SETTING

The study was conducted in an urban community setting.

PARTICIPANTS

Six hundred forty-three persons aged 65 and over participated in the study.

MEASUREMENTS

Dementia was defined using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnostic features of dementia.

RESULTS

Dementia prevalence ranged from 2.6% in persons aged 65 to 69 to 32.6% in persons aged 85 and older. Age-standardized prevalence was 8.2% for dementia, 5.4% for Alzheimer's disease, and 2.0% for vascular dementia. The prevalence estimates, which excluded very mild cases (clinical dementia rating index 0.5), were approximately 5.3% for dementia and 4.3% for Alzheimer's disease.

CONCLUSION

The prevalence of dementia in older people in Seoul appears to be somewhat lower than in rural areas of Korea. Considering the difficulties involved in establishing a diagnostic threshold for dementia, actual differences in dementia prevalence between Asian populations are probably minimal.

Prevalence of dementia in the older Japanese-Brazilian population

The prevalence of dementing disorders in Campo Grande of a community of Japanese-Brazilians who immigrated from Okinawa was studied. Previous reports showed that the dietary pattern in Japanese immigrants in Brazil, which characterized by a low fish and large meat intake, is possibly responsible for increased risk of cardiovascular diseases compared with Japanese in Okinawa. A total of 157 persons over 70-year-old were examined, and 19 cases were diagnosed as having dementia. The prevalence (cases/100 aged 70-year-older) was 12.1 for all types of dementia, 5.7 for Alzheimer's disease (AD), 0.6 for vascular dementia (VD), 4.5 for mixed dementia (AD/VD) and 1.3 for other types of dementia. There was no case of dementia with Lewy bodies or frontotemporal lobar degeneration. These results are similar to many previous studies in Western countries and some recent surveys in Japan, and clearly show that more AD than VD appears even in the Japanese-Brazilian population. The higher prevalence rate of dementia in Japanese-Brazilians compared with several studies in Japan may indicate the importance of dietary factors rather than genetic factors.

Prevalence of Alzheimer's disease, vascular dementia and dementia with Lewy bodies in a Japanese population

We studied the prevalence of dementing disorders in a rural town of Japan (Amino-cho), using a door-to-door two-phase design. Of the 170 persons screened as having cognitive impairment, 142 cases were diagnosed as having dementia. The prevalence (cases/100 aged 65 years older) was 3.8 for all types of dementia, 2.1 for Alzheimer's disease (AD), 1.0 for vascular dementia (VD) and 0.7 for other types of dementia. Among other types of dementia, there were four male patients with dementia with Lewy bodies (prevalence: 0.1), but no patients with frontotemporal lobar degeneration. The overall prevalence was higher in women for AD, while that of VD was the same in both sexes. With results similar to many previous studies in Western countries and some recent surveys in Japan, the present sudy clearly showed that AD is more prevalent than VD.

Chlamydia pneumoniae and cardiovascular disease: an evolutionary perspective on infectious causation and antibiotic treatment

Evolutionary considerations implicate infectious causation of atherosclerosis and help to resolve different risk factors as parts of an overall process of disease causation. An evolutionary approach also provides insight for the timing of research efforts to provide better control of pathogen evolution. In particular, evolutionary considerations emphasize the need to understand the transmissibility of Chlamydia pneumoniae from systemic infections in order to control the evolution of antibiotic resistance.

Presenilin-2 mutation and polymorphism in Japanese Alzheimer disease patients

The Asn141Ile mutation of the presenilin 2 gene is responsible for familial early-onset Alzheimer disease found in Volga-German kindreds. However, the genetic influence of presenilin 2 gene on sporadic Alzheimer disease remains unknown. In this study, the frequency of the mutation and genetic association with the presenilin 2 locus were investigated in Japanese sporadic cases. The Asn141Ile mutation was not found in 88 cases of sporadic Alzheimer disease or 13 unrelated cases of familial Alzheimer disease. Fifty cases of late onset sporadic Alzheimer disease and 50 age-matched controls indicated no association with an exon 3 polymorphism of the presenilin 2 gene. These results indicate that the presenilin 2 mutation is not a major cause of Alzheimer disease.