Some Epidemiological Characteristics of Dementia in the Elderly in Two Districts of Hanoi

prevention in a dementia prevention model appropriate for people

elderly in four communes and wards in Hanoi area.

Currently, most domestic studies on the elderly with dementia focus on rural areas [18], or urban areas [52], or on clinical and treatment [2], [4]. Our study has presented data on the elderly with dementia in both rural and urban areas of Vietnam, which is the basis for more comprehensive health care for the elderly.

4.2. Some epidemiological characteristics of dementia in the elderly in two districts of Hanoi

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4.2.1. Prevalence of dementia

The results of the study on some epidemiological characteristics of dementia (Table 3.5 and chart 3.4) show that: The rate of elderly people with dementia in both urban and suburban areas is 4.24%; in which, the rate of dementia in two communes (Thanh Xuan and Minh Tri) is 5.06%, higher than that in two wards (Phuong Mai and Kim Lien) is 3.56%. The rate of dementia in two suburban communes of Soc Son district (5.06%) is similar to the research results of Nguyen Ngoc Hoa in suburban district of Ba Vi, Hanoi (4.6%; 95%CI=4.03-5.12) [18]. The rate of dementia in two inner-city wards of Dong Da district (3.56%) is lower than the research results of Nguyen Kim Viet in two wards of Thai Nguyen city (4.7%) [52].

Yamada M. et al. [233] studied 637 men and 1,585 women aged 60 and over in the framework of the Hiroshima and Nagasaki Adult Health Study (Japan) and found that the prevalence of dementia (7.2%) was higher than the results of this study (4.24%). However, the authors diagnosed dementia using slightly different DSM III/R criteria than we used DSM IV criteria.

Dartigues JF et al. [91] conducted the PAQUID cohort study of 1,461 people over 75 years old. The results showed that 17.8% of the subjects had dementia, 38.5% of whom lived in nursing homes. The authors' results were higher than ours, however, in our study, to determine the prevalence, we conducted a cross-sectional descriptive study and the study subjects were people aged 60 years and older. Prencipe M. et al. [182] studied 1,147 people over 65 years old and found a prevalence of dementia of 8%, which was higher than the results in our study. Hofman A [116] and Launer LJ studied 7,528 people aged 55 to 106 years and found that the prevalence of dementia was 6.3%, higher than the rate in our study (4.24%). However, the subjects of these authors' study were 65 years of age and older, different from our subjects who were 60 years of age and older.

The results of our study in the suburban area of Hanoi are quite similar to the results of Ferri CP et al. studying 750 people over 60 years old living in a suburban community of Madras city, South India, with a prevalence of dementia of 3.5%. The authors also found that the results in rural areas were higher than in urban areas. However, Ferri CP used the Mental State Schedule (MSS) scale, which is different from ours, which uses the MMSE scale, which is widely used today. Zhang My et al. [235] studied 5,055 people over 65 years old in Shanghai and found a prevalence of dementia of 4.6%. This result is quite similar to our results, but our subjects were 60 years old and above.

The results of our study in two suburban communes are similar to the study of Wang W et al. [220] conducted in a rural area of Beijing on 5,003 people over 60 years old, showing that the overall incidence of dementia was 2.68%, lower than the results of our study (4.24%).

Compared with domestic and foreign research works [91], [182], [116], [220], [233], [235] on the prevalence of dementia, we found that: although the prevalence of dementia in the studies of authors in Europe is mostly higher than ours, the research subjects of the authors are all 65 years of age or older, and the authors used a cohort research method.

Our results are quite consistent with the observations of some authors in Asia. Most of the studies by Asian authors were conducted in rural areas, while our study included both urban and rural areas.

4.2.2. Dementia incidence by age group

The older the elderly are, the higher the incidence of dementia, with the rate increasing 1.5 to 2 times every 5 to 10 years (Table 3.6). Our observation is consistent with Nguyen Ngoc Hoa's research results in Ba Vi district, Hanoi [18], and Nguyen Kim Viet's in Thai Nguyen [52]. However, Nguyen Ngoc Hoa only conducted research in rural suburban areas, while Nguyen Kim Viet only conducted statistics in urban areas. Our research was conducted in both urban and rural areas.

The observation that the higher the age, the higher the rate of dementia has also been confirmed by Hannien T [111], Ikeda M [120], Kumar R [137] and Qui CJ [184]. Our results are consistent with the observations of Ferri CP [101] and Tesvos et al. [215]: every 5 years, the incidence of dementia nearly doubles, specifically increasing from 0.6% in the 60-64 age group to 25.0% in the 90 age group and above.

According to Hofman A [116], the incidence rate changes with age from 0.4% in the 55-59 age group to 43.2% in the over 95 age group. However, the age of the subjects in our study was 60 years old and above, different from the age of the subjects in the authors' study, which were mostly 65 years old and above.

4.2.3. Prevalence of dementia by gender

Our study (Table 3.7) showed that: The rate of dementia in women was 4.8%, higher than that in men at 3.6%. This difference was not statistically significant.

This finding of the incidence of the disease by gender is similar to the results of Nguyen Ngoc Hoa [18], Nguyen Kim Viet et al. [52]. Similar to the incidence of dementia by age group, currently almost no domestic author has conducted research on the elderly with dementia by gender in the inner city area.

Yamada M. et al. [233] showed that the prevalence of vascular dementia was 1.8% in women, which was slightly lower than that in men (2%). Brenner DE [78], Li G et al. [146] found no gender difference at the time of disease onset. Prencipe M. et al. [182] also found no difference between men and women.

Meanwhile, the study of Wang W et al. [220] showed that the prevalence of dementia in general and Alzheimer's disease in particular increased with age, with women being more affected than men, but the difference was not clear with vascular dementia. Woo JI et al. [230] showed that the prevalence of dementia was 9.5% (the difference between men and women was not different: 8.8% in men and 9.9% in women).

Thus, the rate of dementia in the elderly by gender did not differ in our study, which is also consistent with the findings of most domestic and foreign authors.

4.2.4. Dementia incidence by educational level

In our study, the incidence of dementia in the elderly decreased with increasing educational level (Table 3.8). The highest incidence was in the lowest educational level, which was literacy, at 10.9%, then decreased with increasing educational levels. The lowest incidence was in the group with high educational level (from university - college - vocational secondary school and above) at 1.8%.

Our observation is also consistent with that of Nguyen Ngoc Hoa [10], Nguyen Kim Viet and colleagues [52].

Prospective studies by Brenner DE et al. [78] and Li G et al. [146] showed that the higher the education level, the lower the association with Alzheimer's disease. Prencipe M. et al. [182] found that people with low education level had a higher incidence of the disease than those with high education level.

Zhang My et al. [235] studied in Shanghai (China) and found that low education is an independent risk factor for dementia. Our study results on the education of elderly people with dementia are also consistent with the authors, but the rate of dementia in our study is different from the rate of the authors mentioned above.

To explain this, we believe that there is a difference in the age of the research subjects: the elderly in our study were 60 years old or older, while the authors' research age was 65 years old or older.

4.2.5. On the incidence of dementia by occupation and economic conditions

In fact, the investigation shows that in two suburban communes, dementia is most common in elderly farmers; in two inner-city wards, it is most common in elderly people who were formerly civil servants and are now retired in the locality. Through the research, we have not yet found elderly people with poor economic conditions suffering from dementia.

Keskinoglu P, Giray H et al. [131] studied the prevalence and risk factors in elderly people living in poor socioeconomic conditions in Izmir, Turkey. The results showed that 91% of people were not educated, 54.6% lived below the poverty line and the rate of dementia was 22.9%. This result is higher than other studies in Europe and America. The authors attributed this to the high rate of illiteracy and poverty in this study and have not confirmed that economic conditions have a real relationship with dementia.

On the role of economic conditions, Keskinoglu P, Giray H et al.

[131] suggested that this may be partly due to the high rates of illiteracy and poverty in this study. However, the authors did not confirm whether dementia was actually associated with economic conditions?

Thus, the issue of occupation and economic conditions related to dementia in the elderly, especially in urban areas, needs further research.

4.2.6. Prevalence of dementia according to medical history

The study results showed that the group with the highest rate of dementia had a personal history of cerebrovascular accident with a dementia rate of 20.8%, while the group without a history of this disease had a significantly lower rate of 3.5% (Table 3.10). This result is consistent with the study of Fujishima M and Kiyohara Y [106] showing that a history of cerebrovascular accident is a risk factor for vascular dementia.

For the group with dementia according to the history of memory loss (Table 3.12), it shows that: the elderly with a history of memory loss and a family member with memory loss account for a significantly higher proportion than the group without this history. Currently, the issue of research on the history of memory loss has not been mentioned much in domestic studies. However, some authors have evaluated the family history of dementia. Nguyen Ngoc Hoa's results show that the current rate

The incidence in this history group was 28.0%, significantly higher than that in the normal history group (3.8%) by 9.8 times [18].

Regarding the incidence of dementia according to history of hypertension, Table 3.9 shows: The incidence of dementia in people with a personal history of hypertension is higher than in people without this history.

Whitmer's blood pressure study [222] showed that middle-aged hypertension was associated with increased dementia. Moore TL et al. [159] also found that hypertension was associated with neurodegenerative markers in the brain, suggesting that chronic hypertension may play a role in the pathogenesis of Alzheimer's disease. In the geriatric age group, the risk factors for hypertension are unclear, while low blood pressure appears to predict dementia and Alzheimer's disease.

The longitudinal study results of Prince M et al. [183] confirm the involvement of low blood pressure in old age and reduced cerebral perfusion in the development of dementia and Alzheimer's disease.

Nguyen Ngoc Hoa [18] in his research in the suburban areas of Hanoi concluded that hypertension is not related to dementia. Authors in the world and in the country have different opinions and have not really confirmed that people with a history of hypertension have a higher risk of dementia than those without this history.

Regarding the history of cardiovascular disease: Carmichael OT et al. [83] found that cardiovascular disease was associated with increased dementia and Alzheimer's disease, especially in those with peripheral vascular disease, suggesting that diffuse peripheral atherosclerosis is a risk factor for dementia. In addition, heart failure and atrial fibrillation may be independently associated with increased dementia.

The Kungsholmen project report [185] also showed that heart failure increases

80% of dementia and Alzheimer's disease are related, but the use of

Antihypertensive drugs may partially offset this association. The authors' observations suggest that the association of a history of cardiovascular disease with dementia is suggestive and that there are differences in our results, with a small difference in the prevalence of dementia between those with and without a history of the disease (Table 3.11).

Regarding the history of diabetes with dementia: The results of studies by Amaiz E et al. [63], Biessel GJ et al. [71] showed that diabetic patients have an increased association with both vascular and degenerative dementia.

According to Qui C et al. [185], borderline diabetes and impaired glucose tolerance are also associated with increased incidence of dementia and Alzheimer's disease. However, Nguyen Ngoc Hoa [18] has not found a relationship between a history of diabetes and dementia. Our study results are also consistent with Nguyen Ngoc Hoa's findings (Table 3.13).

Regarding the incidence of dementia in people with a history of hyperlipidemia, the studies of Refolo LM [189] and Signoret JL [206] only suggestive of the association between hyperlipidemia and dementia, especially in the group without Alzheimer's disease, while the study of Dufouil C et al. [97] showed no such association, and even found an inverse association between lipid disorders and dementia. Thus, on this issue, scientists' views are still different. In our study, there was no significant difference in the incidence of dementia in people with a history of hyperlipidemia and people without this history (Table 3.14).

Regarding the association between some predisposing factors and dementia, some authors have suggested that the incidence of the disease is higher in people who have close relatives with dementia. According to the Alzheimer's Research Association, people with Down syndrome have a higher rate of disease progression in middle age. This may be due to genetic differences. Some studies have found some predisposing factors on chromosomes 1, 14, 21 [23].

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