Dementia: Dementia incidence - the times, they are a-changing

Imbalanced clearance of Aβ peptide cause presynaptic plaque formation

Alzheimer's disease is characterized by abnormal increase of Aβ peptide which is likely as the result of imbalanced homeostasis of its production and clearance mechanisms. Here, we briefly review that the uncleaned extracellular Aβ peptides are loaded into presynaptic neurons. The Aβ oligomers desperately affect pre- and post-synapse neuron activity and turn into plaques inside the presynaptic neurons over the time passes.

VasCog 2023: 20 years of research on vascular behavioural and cognitive disorders

This Commentary describes the 20th Anniversary of VasCog 2023, held in Gothenburg, Sweden.

2024 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including prevalence and incidence, mortality and morbidity, use and costs of care and the ramifications of AD for family caregivers, the dementia workforce and society. The Special Report discusses the larger health care system for older adults with cognitive issues, focusing on the role of caregivers and non-physician health care professionals. An estimated 6.9 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060, barring the development of medical breakthroughs to prevent or cure AD. Official AD death certificates recorded 119,399 deaths from AD in 2021. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death in the United States. Official counts for more recent years are still being compiled. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2021, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 140%. More than 11 million family members and other unpaid caregivers provided an estimated 18.4 billion hours of care to people with Alzheimer's or other dementias in 2023. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $346.6 billion in 2023. Its costs, however, extend to unpaid caregivers' increased risk for emotional distress and negative mental and physical health outcomes. Members of the paid health care and broader community-based workforce are involved in diagnosing, treating and caring for people with dementia. However, the United States faces growing shortages across different segments of the dementia care workforce due to a combination of factors, including the absolute increase in the number of people living with dementia. Therefore, targeted programs and care delivery models will be needed to attract, better train and effectively deploy health care and community-based workers to provide dementia care. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2024 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $360 billion. The Special Report investigates how caregivers of older adults with cognitive issues interact with the health care system and examines the role non-physician health care professionals play in facilitating clinical care and access to community-based services and supports. It includes surveys of caregivers and health care workers, focusing on their experiences, challenges, awareness and perceptions of dementia care navigation.

2023 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease, including prevalence and incidence, mortality and morbidity, use and costs of care, and the overall impact on family caregivers, the dementia workforce and society. The Special Report examines the patient journey from awareness of cognitive changes to potential treatment with drugs that change the underlying biology of Alzheimer's. An estimated 6.7 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, and Alzheimer's disease was officially listed as the sixth-leading cause of death in the United States. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. This trajectory of deaths from AD was likely exacerbated by the COVID-19 pandemic in 2020 and 2021. More than 11 million family members and other unpaid caregivers provided an estimated 18 billion hours of care to people with Alzheimer's or other dementias in 2022. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $339.5 billion in 2022. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Members of the paid health care workforce are involved in diagnosing, treating and caring for people with dementia. In recent years, however, a shortage of such workers has developed in the United States. This shortage - brought about, in part, by COVID-19 - has occurred at a time when more members of the dementia care workforce are needed. Therefore, programs will be needed to attract workers and better train health care teams. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2023 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $345 billion. The Special Report examines whether there will be sufficient numbers of physician specialists to provide Alzheimer's care and treatment now that two drugs are available that change the underlying biology of Alzheimer's disease.

The Influence of Birth Cohorts on Future Cognitive Decline

BACKGROUND

Slowed rates of cognitive decline have been reported in individuals with higher cognitive reserve (CR), but interindividual discrepancies remain unexplained. Few studies have reported a birth cohort effect, favoring later-born individuals, but these studies remain scarce.

OBJECTIVE

We aimed to predict cognitive decline in older adults using birth cohorts and CR.

METHODS

Within the Alzheimer's Disease Neuroimaging Initiative, 1,041 dementia-free participants were assessed on four cognitive domains (verbal episodic memory; language and semantic memory; attention; executive functions) at each follow-up visit up to 14 years. Four birth cohorts were formed according to the major historical events of the 20th century (1916-1928; 1929-1938; 1939-1945; 1946-1962). CR was operationalized by merging education, complexity of occupation, and verbal IQ. We used linear mixed-effect models to evaluate the effects of CR and birth cohorts on rate of performance change over time. Age at baseline, baseline structural brain health (total brain and total white matter hyperintensities volumes), and baseline vascular risk factors burden were used as covariates.

RESULTS

CR was only associated with slower decline in verbal episodic memory. However, more recent birth cohorts predicted slower annual cognitive decline in all domains, except for executive functions. This effect increased as the birth cohort became more recent.

CONCLUSION

We found that both CR and birth cohorts influence future cognitive decline, which has strong public policy implications.

2022 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including incidence and prevalence, mortality and morbidity, use and costs of care, and the overall impact on family caregivers, the dementia workforce and society. The Special Report discusses consumers' and primary care physicians' perspectives on awareness, diagnosis and treatment of mild cognitive impairment (MCI), including MCI due to Alzheimer's disease. An estimated 6.5 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, the latest year for which data are available. Alzheimer's disease was officially listed as the sixth-leading cause of death in the United States in 2019 and the seventh-leading cause of death in 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. More than 11 million family members and other unpaid caregivers provided an estimated 16 billion hours of care to people with Alzheimer's or other dementias in 2021. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $271.6 billion in 2021. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Members of the dementia care workforce have also been affected by COVID-19. As essential care workers, some have opted to change jobs to protect their own health and the health of their families. However, this occurs at a time when more members of the dementia care workforce are needed. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2022 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $321 billion. A recent survey commissioned by the Alzheimer's Association revealed several barriers to consumers' understanding of MCI. The survey showed low awareness of MCI among Americans, a reluctance among Americans to see their doctor after noticing MCI symptoms, and persistent challenges for primary care physicians in diagnosing MCI. Survey results indicate the need to improve MCI awareness and diagnosis, especially in underserved communities, and to encourage greater participation in MCI-related clinical trials.

Birth Cohorts and Cognitive Reserve Influence Cognitive Performances in Older Adults

BACKGROUND

Evidence suggests birth cohort differences in cognitive performance of older adults. Proxies of cognitive reserve (CR), such as educational attainment and occupational complexity, could also partly account for these differences as they are influenced by the sociocultural environment of the birth cohorts.

OBJECTIVE

To predict cognitive performance using birth cohorts and CR and examine the moderating influence of CR on cognitive performance and structural brain health association.

METHODS

Using ADNI data (n = 1628), four birth cohorts were defined (1915-1928; 1929-1938; 1939-1945; 1946-1964). CR proxies were education, occupational complexity, and verbal IQ. We predicted baseline cognitive performances (verbal episodic memory; language and semantic memory; attention capacities; executive functions) using multiple linear regressions with CR, birth cohorts, age, structural brain health (total brain volume; total white matter hyperintensities volume) and vascular risk factors burden as predictors. Sex and CR interactions were also explored.

RESULTS

Recent birth cohorts, higher CR, and healthier brain structures predicted better performance in verbal episodic memory, language and semantic memory, and attention capacities, with large effect sizes. Better performance in executive functions was predicted by a higher CR and a larger total brain volume, with a small effect size. With equal score of CR, women outperformed men in verbal episodic memory and language and semantic memory in all cohorts. Higher level of CR predicted better performance in verbal episodic memory, only when total brain volume was lower.

CONCLUSION

Cohort differences in cognitive performance favor more recent birth cohorts and suggests that this association may be partly explained by proxies of CR.

Time trends in the relation between blood pressure and dementia in 85-year-olds

OBJECTIVES

Blood pressure has decreased in the general population. We aimed to examine whether this is true also among the very old, and among persons with and without dementia. Further, we aimed to investigate how common undetected and untreated hypertension is in the very old, both among people with and without dementia.

METHOD

Blood pressure was measured in representative population samples of 85-year-olds living in Gothenburg, Sweden, examined 1986-1987 (n = 484) and 2008-2010 (n = 571). Dementia was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, edition 3 revised, by the same medical doctor at both examinations.

RESULTS

Both systolic and diastolic blood pressure were lower in 85-year-olds examined 2008-2010 than in those examined 1986-1987, both among those with and without dementia. Participants with dementia had lower systolic blood pressure than those without dementia in both cohorts, and blood pressure levels related to dementia severity. Despite this, hypertension (≥140/90 mmHg) was found in almost half (46.5%) of those with dementia in 2008-2010.

CONCLUSION

Our findings show that time-trends of lower blood pressure in western populations also applies to the very old, and that individuals with dementia continue to have lower blood pressure compared to the rest of the population. The latter finding suggests that the pathophysiological processes in dementia affect blood pressure regulating regions in the brain independent of time trends. Still, hypertension is common in dementia and needs to be detected and treated.

Dementia remains the major predictor of death among octogenarians. A study of two population cohorts of 85-year-olds examined 22 years apart

Dementia is the major predictor of death in old age. The aim of this paper was to determine whether 8-year mortality among 85-year olds with and without dementia, and if the contribution of dementia to mortality relative to other common diseases has changed. We used two population-based cohorts of 85-year-olds (N = 1065), born in 1901–02 and 1923–24, which were examined with identical methods in 1986–87 and 2008–2010 and followed for 8-year mortality according to data from the Swedish Tax Agency. Dementia was diagnosed according to DSM-III-R. Other diseases were diagnosed based on self-reports, close informant interviews, somatic examinations, and the Swedish National In-patient Register. Compared to cohort 1901–02, cohort 1923–24 had a lower 8-year mortality both among those with (HR 0.7; 95% CI 0.5–0.99) and without dementia (HR 0.7; 95% CI 0.5–0.9). Dementia was associated with increased mortality in both cohorts (cohort 1901–02, HR 2.6; 95% CI 2.0–3.2, cohort 1923–24, HR 2.8; 95% CI 2.3–3.5), and remained the major predictor of death, with a population attributable risk of 31.7% in 1986–87 and 27.7% in 2008–10. Dementia remained the most important predictor of death in both cohorts. The relative risk for mortality with dementia did not change between cohorts, despite a decreased mortality rate in the population.

Association of Demographic and Early-Life Socioeconomic Factors by Birth Cohort With Dementia Incidence Among US Adults Born Between 1893 and 1949

IMPORTANCE

Early-life factors may be important for later dementia risk. The association between a more advantaged early-life environment, as reflected through an individual's height and socioeconomic status indicators, and decreases in dementia incidence by birth cohort is unknown.

OBJECTIVES

To examine the association of birth cohort and early-life environment with dementia incidence among participants in the Adult Changes in Thought study from 1994 to 2015.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study included 4277 participants from the Adult Changes in Thought study, an ongoing longitudinal population-based study of incident dementia in a random sample of adults 65 years and older who were born between 1893 and 1949 and are members of Kaiser Permanente Washington in the Seattle region. Participants in the present analysis were followed up from 1994 to 2015. At enrollment, all participants were dementia-free and completed a baseline evaluation. Subsequent study visits were held every 2 years until a diagnosis of dementia, death, or withdrawal from the study. Participants were categorized by birth period (defined by historically meaningful events) into 5 cohorts: pre-World War I (1893-1913), World War I and Spanish influenza (1914-1920), pre-Great Depression (1921-1928), Great Depression (1929-1939), and World War II and postwar (1940-1949). Participants' height, educational level, childhood financial stability, and childhood household density were examined as indicators of early-life environment, and later-life vascular risk factors for dementia were assessed. Cox proportional hazards regression models, adjusted for competing survival risk, were used to analyze data. Data were analyzed from June 1, 2018, to April 29, 2020.

MAIN OUTCOMES AND MEASURES

Participants completed the Cognitive Abilities Screening Instrument every 2 years to assess global cognition. Those with scores indicative of cognitive impairment completed an evaluation for dementia, with dementia diagnoses determined during consensus conferences using criteria from the Diagnostic and Statistical Manual of Mental Disorders, 4th edition.

RESULTS

Among 4277 participants, the mean (SD) age was 74.5 (6.4) years, and 2519 participants (58.9%) were women. The median follow-up was 8 years (interquartile range, 4-12 years), with 730 participants developing dementia over 24 378 person-years. The age-specific dementia incidence was lower for those born in 1929 and later compared with those born earlier. Compared with participants born in the pre-Great Depression years (1921-1928), the age- and sex-adjusted hazard ratio was 0.67 (95% CI, 0.53-0.85) for those born in the Great Depression period (1929-1939) and 0.62 (95% CI, 0.29-1.31) for those born in the World War II and postwar period (1940-1949). Although indicators of a more advantaged early-life environment and higher educational level (college or higher) were associated with a lower incidence of dementia, these variables did not explain the association between birth cohort and dementia incidence, which remained when vascular risk factors were included and were similar by sex.

CONCLUSIONS AND RELEVANCE

Age-specific dementia incidence was lower in participants born after the mid-1920s compared with those born earlier. In this population, the decrease in dementia incidence may reflect societal-level changes or individual differences over the life course rather than early-life environment, as reflected through recalled childhood socioeconomic status and measured height, educational level, and later-life vascular risk.

Is the prevalence of psychosis in the very old decreasing? A comparison of 85-year-olds born 22 years apart

OBJECTIVE

To elucidate whether there is a decrease of psychotic symptoms in 85-years-olds without dementia and if factors associated with psychotic symptoms have changed, we studied two birth cohorts of 85-year-olds born 22 years apart.

METHODS

Every second, 85-year-olds in Gothenburg, Sweden was invited to neuropsychiatric examinations in 1986 to 1987 (participation 63.1%, N = 494) and in 2008 to 2010 (60.5%, N = 571). A close informant was interviewed by a psychiatrist or a research psychologist.

RESULTS

The prevalence of psychotic symptoms in 85-years-olds without dementia decreased from 10.1% in 1986 to 1987 to 3.2% in 2008 to 2010 (P < .001). Disability in daily life (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.1-4.5), depressed mood (OR, 3.9; 95% CI, 2.1-7.1), irritability (OR, 3.6; 95% CI, 1.2-10.5), and suicidal ideation (OR, 4.1; 95% CI, 2.1-8.0) were associated with psychotic symptoms in both cohorts. Mean mini-mental state examination (MMSE) score was lower in those with psychotic symptom compared with those with no psychotic symptoms (Cohort 1986-1987, 26.4 vs 27.8, Cohort 2008-2009, 26.1 vs 27.7, t value -4.24, Pr > t < 0.001).

CONCLUSION

The prevalence of psychotic symptoms decreased between 1986 to 1987 and 2008 to 2010 among 85-years-olds without dementia. These symptoms were associated with broad psychopathology, worse performance in cognitive testing, and with disability of daily life in both cohorts.

Depression and neuroticism decrease among women but not among men between 1976 and 2016 in Swedish septuagenarians

OBJECTIVES

We evaluated birth-cohort differences in depressive symptom burden, prevalence of depression diagnoses, and neuroticism, among Swedish 70-year-olds examined between 1976 and 2016.

METHODS

We used a repeated cross-sectional design examining four representative population samples of Swedish 70-year-olds (total n = 2279) with identical methods in 1976-77 (n = 392), 1992-93 (n = 226), 2000-02 (n = 487), and 2014-16 (n = 1166). Depressive symptom burden was rated with the Montgomery Åsberg Depression Rating Scale. Major depression was diagnosed according to DSM-5, and minor depression according to DSM-IV-TR research criteria. Neuroticism was rated with the Eysenck Personality Inventory.

RESULTS

For women in 2014-16, MADRS score (4.4 vs. 6.1 vs. 5.8; P < 0.05) and neuroticism (6.6 vs. 7.7 vs. 9.2; P < 0.05) were lower compared with 1992-93 and 1976-77, and the prevalence of any depression was lower compared with 2000-02 and 1992-93 (10.9% vs. 16.9% vs. 18.1%; P < 0.05). For men, we observed no birth-cohort differences in depression, while neuroticism was found to be lower in 2014-16 compared with 1976-77 among men without depression (5.1 vs. 5.9; P < 0.01). The sex difference for MADRS and neuroticism declined between 1976-77 and 2014-16 (cohort*sex P < 0.05).

CONCLUSIONS

Depressive burden and neuroticism decreased in 70-year-old women between 1976 and 2016.

Increased Alcohol Consumption Among Swedish 70-Year-Olds 1976 to 2016: Analysis of Data from The Gothenburg H70 Birth Cohort Studies, Sweden

BACKGROUND

The older adult population is increasing worldwide, as is the number of older adults who consume alcohol. Although there is a growing body of research on alcohol consumption among older people, few studies focus on changes in at-risk consumption over time across well-defined birth cohorts of older adults.

METHODS

This study used a serial cross-sectional design in order to compare alcohol consumption patterns among birth cohorts of Swedish 70-year-olds (total n = 2,268) examined in 1976 to 1977 (n = 393), 1992 to 1993 (n = 248), 2000 to 2002 (n = 458), and 2014 to 2016 (n = 1,169). Participants took part in a multidisciplinary study on health and aging. Face-to-face interviews were conducted by healthcare professionals. Protocols regarding alcohol consumption were similar for all cohorts. The volume of weekly alcohol consumption was estimated during the past month. At-risk consumption was defined as ≥100 g alcohol/wk corresponding roughly to the National Institute on Alcohol Abuse and Alcoholism definition of heavy consumption.

RESULTS

The proportion of at-risk consumers among men increased from 16.1% in 1976 to 1977 to 29.9% in 2000 to 2002 (p = 0.001) and 45.3% in 2014 to 2016 (p < 0.001). In women, proportions were low in 1976 to 1977 (0.5%) and 1992 to 1993 (2.0%; p = 0.134), but increased to 9.5% in 2000 to 2002 (p < 0.001) and 24.3% in 2014 to 2016 (p < 0.001). The male:female ratio regarding consumption of ≥100 g/wk decreased from 32.2:1 in 1976 to 1977 to 3.1:1 in 2000 to 2002 to 1.9:1 in 2014 to 2016. Spirit consumption decreased dramatically among men during the study period, while women reported very low spirit consumption at all examinations. Wine consumption increased in both sexes between 2000 to 2002 and 2014 to 2016. Beer consumption increased among men between 2000 to 2002 and 2014 to 2016.

CONCLUSIONS

Recent cohorts of 70-year-olds in Sweden report significantly higher levels of alcohol consumption than previous cohorts. There was a dramatic increase in at-risk consumption among 70-year-olds from the 1970s to the mid-2010s, and this was particularly pronounced among women.

Is dementia incidence declining in high-income countries? A systematic review and meta-analysis

Purpose

To perform a systematic review and quantitative synthesis of studies on recent trends in dementia incidence in high-income countries (HIC), considering study quality.

Methods

PubMed and Web of Science were searched for eligible studies, that is, population-based/community-based prospective cohort studies investigating dementia incidence with similar methods over time, published after 1990. Study selection, data extraction, and quality assessment were performed independently by two investigators. Random-effect meta-analysis and meta-regression were used to estimate incidence change (IC) and to explore associations with study attributes. PRISMA standards were followed.

Results

The systematic review included seven studies (42,485 individuals), and the meta-analysis included five studies of sufficient quality. Relating dementia incidence of later cohorts to earlier cohorts (reference) yielded a nonsignificant decrease across HIC (IC =0.82; 95% CI 0.51–1.33), with high heterogeneity (I²=94.9%, P<0.001) and without publication bias (Egger’s t=–1.77; P=0.18). Excluding the Japanese Hisayama study, the only study suggesting an increase, indicated borderline evidence for a decrease across Western HIC (IC =0.69; 95% CI 0.47–1.00; I²=88.1%, P<0.001; Egger’s t=–0.34, P=0.77), again with high heterogeneity. Meta-regression did not reveal an association of incidence rate with calendar year or study attributes; however, analyses were low powered.

Conclusion

There is evidence of favorable trends in dementia incidence in Western HIC (stabilizing/decreasing). Reverse trends may occur in HIC of other regions, as exemplified by Japan. However, study number was small and heterogeneity was high. Further cohort studies using consistent methods are needed to draw definite conclusions. Our work may inform such future studies.

Sex differences in time trends of blood pressure among Swedish septuagenarians examined three decades apart: a longitudinal population study

OBJECTIVE

The aim of this study was to analyze the influence of birth cohort, sex and age on the trajectories of SBP and DBP in two birth cohorts of 70-year-olds, examined 3 decades apart and followed up at ages 75 and 79-80 years.

METHODS

Two population samples of 70-year-olds from Gothenburg, Sweden, were examined. The first, born in 1901-1902, was examined in 1971-1972 (n = 973). The second, born in 1930, was examined in 2000 (n = 509). Both samples were re-examined at ages 75 and 79-80 years.

RESULTS

We found that SBP and DBP were considerably lower in septuagenarian men and women born 1930 compared with those born 1901-1902, also when adjusting for antihypertensive treatment in different ways. The decline was especially pronounced in women. Blood pressure was higher in women than in men in the 1970s, whereas there were no sex differences in the 2000s. The age-related decline in SBP started earlier and was more accentuated in those born in 1930 than in those born in 1901-1902.

CONCLUSION

Blood pressure decreased, and the age-related decline in SBP started earlier in septuagenarians examined in the 2000s compared with those examined in the 1970s. The decrease was especially pronounced in women and diminished the sex differences. Antihypertensive treatment only partly explained our findings, suggesting that other mostly unknown factors played an important role.

Vascular cognitive impairment

The term vascular cognitive impairment (VCI) was introduced around the start of the new millennium and refers to the contribution of vascular pathology to any severity of cognitive impairment, ranging from subjective cognitive decline and mild cognitive impairment to dementia. Although vascular pathology is common in elderly individuals with cognitive decline, pure vascular dementia (that is, dementia caused solely by vascular pathology) is uncommon. Indeed, most patients with vascular dementia also have other types of pathology, the most common of which is Alzheimer disease (specifically, the diffuse accumulation of amyloid-β plaques and neurofibrillary tangles composed of tau). At present, the main treatment for VCI is prevention by treating vascular diseases and other risk factors for VCI, such as hypertension and diabetes mellitus. Despite the current paucity of disease-modifying pharmacological treatments, we foresee that eventually, we might be able to target specific brain diseases to prevent cognitive decline and dementia.

Population Neuroscience: Dementia Epidemiology Serving Precision Medicine and Population Health

Over recent decades, epidemiology has made significant contributions to our understanding of dementia, translating scientific discoveries into population health. Here, we propose reframing dementia epidemiology as "population neuroscience," blending techniques and models from contemporary neuroscience with those of epidemiology and biostatistics. On the basis of emerging evidence and newer paradigms and methods, population neuroscience will minimize the bias typical of traditional clinical research, identify the relatively homogenous subgroups that comprise the general population, and investigate broader and denser phenotypes of dementia and cognitive impairment. Long-term follow-up of sufficiently large study cohorts will allow the identification of cohort effects and critical windows of exposure. Molecular epidemiology and omics will allow us to unravel the key distinctions within and among subgroups and better understand individuals' risk profiles. Interventional epidemiology will allow us to identify the different subgroups that respond to different treatment/prevention strategies. These strategies will inform precision medicine. In addition, insights into interactions between disease biology, personal and environmental factors, and social determinants of health will allow us to measure and track disease in communities and improve population health. By placing neuroscience within a real-world context, population neuroscience can fulfill its potential to serve both precision medicine and population health.

Time, Sex, Gender, History, and Dementia

A growing body of epidemiologic evidence indicates a decline in the incidence or prevalence of dementia in high income countries in the past 25 years. In this commentary, I first suggest that the decline in the incidence or prevalence of dementia is not explained completely by the factors considered so far, and that a broader historical perspective may be needed. Second, I suggest that the overall declining trend may conceal trends in opposite directions for the two major subtypes of dementia, the neurovascular and the neurodegenerative type. Third, I suggest some areas of future research to further elucidate the trends. The future of dementia remains somewhat unclear. Even if the incidence continues to decline, the prevalence may remain the same or increase if survival of persons affected by dementia increases. In addition, even if the prevalence declines, the total number of persons affected by dementia may remain the same or increase if the size of the elderly population expands. Finally, we cannot be sure that the decline in incidence will continue in the coming decades. With cautious optimism, we may conclude that the burden of dementia may be modified over time by human practices, including public health and medicine.

Decreasing prevalence of dementia in 85-year olds examined 22 years apart: the influence of education and stroke

Individuals aged 80 years and older constitute the fastest growing segment of the population worldwide, leading to an expected increase in dementia cases. Education level and treatment of vascular risk factors has increased during the last decades. We examined whether this has influenced the prevalence of dementia according to DSM-III-R using population-based samples of 85-year-olds (N = 1065) examined with identical methods 1986–87 and 2008–10. The prevalence of dementia was 29.8% in 1986–87 and 21.7% in 2008–10 (OR 0.66; 95%-CI: 0.50–0.86). The decline was mainly observed for vascular dementia. The proportion with more than basic education (25.2% and 57.7%), and the prevalence of stroke (20% and 30%) increased, but the odds ratio for dementia with stroke decreased from 4.3 to 1.8 (interaction stroke*birth cohort; p = 0.008). In a logistic regression, education (OR 0.70; 95%-CI 0.51–0.96), stroke (OR 3.78; 95%-CI 2.28–6.29), interaction stroke*birth cohort (OR 0.50; 95%-CI 0.26–0.97), but not birth cohort (OR 0.98; 95%-CI 0.68–1.41), were related to prevalence of dementia. Thus, the decline in dementia prevalence was mainly explained by higher education and lower odds for dementia with stroke in later born birth cohorts. The findings may be related to an increased cognitive reserve and better treatment of stroke in later-born cohorts.

The changing prevalence and incidence of dementia over time - current evidence

Dementia is an increasing focus for policymakers, civil organizations and multidisciplinary researchers. The most recent descriptive epidemiological research into dementia is enabling investigation into how the prevalence and incidence are changing over time. To establish clear trends, such comparisons need to be founded on population-based studies that use similar diagnostic and research methods consistently over time. This narrative Review synthesizes the findings from 14 studies that investigated trends in dementia prevalence (nine studies) and incidence (five studies) from Sweden, Spain, the UK, the Netherlands, France, the USA, Japan and Nigeria. Besides the Japanese study, these studies indicate stable or declining prevalence and incidence of dementia, and some provide evidence of sex-specific changes. No single risk or protective factor has been identified that fully explains the observed trends, but major societal changes and improvements in living conditions, education and healthcare might have favourably influenced physical, mental and cognitive health throughout an individual's life course, and could be responsible for a reduced risk of dementia in later life. Analytical epidemiological approaches combined with translational neuroscientific research could provide a unique opportunity to explore the neuropathology that underlies changing occurrence of dementia in the general population.

Linking deregulation of non-coding RNA to the core pathophysiology of Alzheimer's disease: An integrative review

The human genome encodes a vast repertoire of protein non-coding RNAs (ncRNA), some specific to the brain. MicroRNAs, which interfere with the translation of target mRNAs, are of particular interest since their deregulation has been implicated in neurodegenerative disorders like Alzheimer's disease (AD). However, it remains challenging to link the complex body of observations on miRNAs and AD into a coherent framework. Using extensive graphical support, this article discusses how a diverse panoply of miRNAs convergently and divergently impact (and are impacted by) core pathophysiological processes underlying AD: neuroinflammation and oxidative stress; aberrant generation of β-amyloid-42 (Aβ42); anomalies in the production, cleavage and post-translational marking of Tau; impaired clearance of Aβ42 and Tau; perturbation of axonal organisation; disruption of synaptic plasticity; endoplasmic reticulum stress and the unfolded protein response; mitochondrial dysfunction; aberrant induction of cell cycle re-entry; and apoptotic loss of neurons. Intriguingly, some classes of miRNA provoke these cellular anomalies, whereas others act in a counter-regulatory, protective mode. Moreover, changes in levels of certain species of miRNA are a consequence of the above-mentioned anomalies. In addition to miRNAs, circular RNAs, piRNAs, long non-coding RNAs and other types of ncRNA are being increasingly implicated in AD. Overall, a complex mesh of deregulated and multi-tasking ncRNAs reciprocally interacts with core pathophysiological mechanisms underlying AD. Alterations in ncRNAs can be detected in CSF and the circulation as well as the brain and are showing promise as biomarkers, with the ultimate goal clinical exploitation as targets for novel modes of symptomatic and course-altering therapy.