Every 3 seconds, someone in the world develops dementia and there is not a single epidemiology for it across the world. In the present study, the prevalence rates of Alzheimer among six geographic regions, including Asia, Africa, North America, South America, Europe and Australia & Oceania showed a positive trend, with minimum and maximum ADD prevalence rate increases (on average) between 3.8 and 82 (rate in 100000) every 5 years in African and European female, respectively. The other regions also showed an increasing trend between these rates. The higher increase prevalence rate in Europe may be justified by reasons within which the rapid aging may be the most significant.
The present study monitored the trends in ADD prevalence rate among all of the mentioned countries, using the LGMM modeling. Based on this study’s analysis, 195 countries and territories were clustered into 7 classes based on their trend of ADD during the 1990 to 2016. According to the clusters, class 3, consisting of Japan, had a dramatically sharp increase from 1990 to 2016 in ADD rate. Fastest aging population may be the main reason for the large growth in the ADD prevalence trend in Japan. If aging is the influencing factor over this trend, according to the “World Atlas” report, Japan is expected to witness an increase in the growth rate of the old population from 27.2% in 2014 to 32.2% in 2030. The consequences of this increase in Alzheimer’s disease will turn into a serious issue in the near future. It’s worth mentioning that though Japan has the oldest population of the world, and Italy and Portugal are in the second and third place after Japan, none of these countries witnessed such sharp increase in their ADD rate. That is why it is inferred that aging population alone cannot be the main factor for such ADD upsurge. Among all counties around the world, Japan with its exemplary technological advances and success allocated the most increasing trend of ADD to itself, which highlights the importance of strategies for early detection, diagnosis and treatment of ADD which should attract more and more attention. Such vivid soar in the results for Japan truly calls for much more attention and speculations.
Regarding the disease diagnosis in Japan, clinical practice for the administration of dementing diseases was established by six main societies in Japan including the Japanese Society of Psychiatry and Neurology, the Japan Society for Dementia Research, the Japanese Psychogeriatric Society, the Japan Geriatrics Society, the Japanese Society of Neurological Therapeutics, and the Japanese Society of Neurology. The guidelines outlined clinical signs, image findings, biochemical markers, and pharmacologic management guidance for ADD. The 2010 guidelines and practical strategies principally correspond to the US Alzheimer’s Disease Management Council consensus for the management of ADD [16]. However, the manner in which diagnoses were made or how data was registered in Japan might be a potential reason for high statistics in comparison to other countries.
Denmark, Norway and Sweden (class 5) had a downward trend of 11.5 until 2016. This decreasing trend may be due to the promoting of strategies related to “Health and health care of the elderly in the Nordic Countries” program. For the purpose of maintaining a healthy diet, good health and good living conditions, together with active participation in social life, one powerful financial position seems crucial. Publicly-financed services such as high-cost protection medicines and health-care systems are often available in the Nordic region. According to the findings of the existing research, brain heath has a close relationship with heart and blood vessel health. Consequently, factors such as smoking, obesity, diabetes, and high cholesterol and high blood pressure in midlife which have a crucial role in causing cardiovascular diseases can be directly connected with a higher risk of developing Alzheimer and other dementias. Preventing cardiovascular diseases through reducing the risk of diabetes, high blood pressure, overweight, smoking and alcohol misuse are among the preventive strategies for dementia. It can be inferred that preventing cardiovascular diseases may lead to preventing dementia. Consequently, higher levels of education and better living conditions, prevention and treatment of cardiovascular diseases which reduces the risk of ADD are the main reasons for the reduction in the rates of ADD. More details are available in the report presented by the Nordic Medico-Statistical Committee [17].
Our results also showed that most of the countries and territories in Europe continent, as well as the United States were clustered in classes with increasing trend of ADD rate (classes 1,4 and 6), rising between 20.4 and 53.6. Most of Asian countries are clustered in class 4, being less likely to increase the prevalence of Alzheimer's compared with other clusters, which include European and American countries. Of course, the differences in the diagnostic criteria used to diagnose dementia are also a likely source of variation in the prevalence of dementia among the reports. Correspondingly, in developing countries like North America, Europe and Australia, the rates of ADD may be registered more accurately when compared with less developed countries such as many Asian ones.
The results of a meta-analysis study have shown that there is good evidence of a decline in the prevalence of Alzheimer's in high-income countries (where Japan is also excluded). Nevertheless, the mentioned paper has proposed the need for stronger and more comprehensive studies as to obtain accurate results regarding the Alzheimer's disease prevalence rate reduction in high-income countries, because this was not probable due to heterogeneity and given the large number of studies and the low sample size [18]. Lack of accurate and reliable data for ADD prevalence rate in some countries may be considered as a limitation of the present study. This limitation causes GBD to report the estimated prevalence rate for some diseases like ADD.
Among the risk factors of ADD, ageing, family history and genetics are the ones that can’t be changed, but due to the growing trend of ADD in some countries, more programs are needed for the purpose of influencing the present crisis through general lifestyle. This program needs in-depth analysis in terms of socio-economic, medical or cultural changes.