Trends in autopsy‐verified dementia prevalence over 29 years of the Hisayama study

Abstract

We investigated the trends in dementia over the past 29 years in the town of Hisayama, Japan using 1266 autopsy specimens. The Hisayama study is a prospective cohort study of lifestyle‐related diseases that was started in 1961. Clinical examination of dementia was started in 1985 with five detailed cross‐sectional assessments conducted in 1985, 1992, 1998, 2005 and 2012. To examine the trends in dementia, we divided the 1266 autopsy samples into five groups according to the year of death: I (1986–1991, 257 cases), II (1992–1997, 268 cases), III (1998–2004, 318 cases), IV (2005–2011, 296 cases) and V (2012–2014, 127 cases). The prevalence of all‐cause dementia significantly increased over time (28.4% in group I, 22.4% in group II, 32.1% in group III, 30.1% in group IV, 51.2% in group V; P for trend <0.001). A similar trend was observed for Alzheimer's disease (AD) (15.2%, 11.9%, 17.3%, 20.6% and 33.1%, respectively; P for trend <0.001). A significant increasing trend was observed in both men and women. A rapid increase in senile dementia of the NFT type (SD‐NFT) in recent years was notable. Vascular dementia was the most common type of dementia in men prior to 2004; however, its prevalence decreased over time. Our study revealed that tauopathies, including AD and SD‐NFT, significantly increased in the aged Japanese population over the course of this study. The neuritic plaque pathology of AD was associated with metabolic disorders such as insulin resistance and abnormal lipid metabolism, whereas the risk factors for tau pathology remain unclear. Although aging is considered one of the important risk factors accelerating tau pathology, there could be other risk factors associated with lifestyle diseases.

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

“…There have been two reports from the Hisayama study in Japan. 20,21 One investigated prevalence trends in the general population while the other focused on an autopsy subsample, which was not representative of the older population in the study area. The former 20 was selected for this analysis.…”

“…The Hisayama study reports an increasing prevalence trend between 1985 and 2005 and the autopsy subsample further suggests a higher prevalence in 2012. 20,21 However, the analysis of the autopsy subsample did not take into account age and potential selection bias. Another Japanese study, which was excluded from this review due to particular screening approaches that do not reflect whole populations, investigated prevalence in all residents in Diasen-Cho area and also report an increasing prevalence across three time points (1980, 1990 and 2000).…”

Basic Ketone Engine and Booster Glucose Engine for Energy Production

“…Alzheimer and other nervous disease: The Hisayama study 25 started in 1961 is a prospective cohort study characterized by all dead people being autopsied. The prevalence of allcauses, dementia and Alzheimer's disease (AD) significantly increased over time.…”

Time, Sex, Gender, History, and Dementia

“…I restrict my consideration to countries with higher income, primarily from Europe and North America, because the time trends of neurological diseases, and of dementia in particular, may be different in other parts of the world with different demographic, social, cultural, and economic characteristics. 12–15 …”

“…Because sex, gender, race and ethnicity, language, religion, diet, medical system, and culture interact with each other within a given political and legal system, we expect different countries (or regions) to experience smaller or bigger time trends, or similar time trends but earlier or later (non synchronous trends). 12,14,15 Different countries may also undergo a bigger trend in men or in women as discussed in the comparison of trends in the United Kingdom and Spain versus the United States and Germany. 1,2,10,23,24 …”