Prevalence of dementia and mild cognitive impairment in the elderly living in nursing and veteran care homes in Xi'an, China

Journal of the Neurological Sciences 312 (2012) 39–44

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Prevalence of dementia and mild cognitive impairment in the elderly living in nursing and veteran care homes in Xi'an, China Mingxian Guo a, Li Gao a, Guihong Zhang a, Yunming Li b, Shasha Xu a, Zhao Wang c, Qiumin Qu d, Feng Guo d,⁎ a

Department of Nursing, the Fourth Military Medical University, Xi'an 710032, China Department of Health Statistics, the Fourth Military Medical University, Xi'an 710032, China Department of Reproductive Endocrinology, the First Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi'an 710061, China d Department of Neurology, the First Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi'an 710061, China b c

a r t i c l e

i n f o

Article history: Received 7 May 2011 Received in revised form 4 August 2011 Accepted 17 August 2011 Available online 3 September 2011 Keywords: Dementia Mild cognitive impairment Prevalence Nursing homes Veteran care homes Risk factors

a b s t r a c t Design: Cross-sectional surveys using cluster sampling. Objectives: To explore the prevalence of dementia and mild cognitive impairment (MCI) in several nursing homes (NHs) and veteran care homes (VCHs) in Xi'an City and their various risk factors. Participants and measurements: 264 native elderly people from four NHs and two VCHs were examined with several screening tests for dementia: Mini Mental State Examination (MMSE), Activities of Daily Living (ADL) and Hasegawa Dementia Scale (HDS). Diagnosis of dementia and MCI were made according to DSM-III-R and Petersen's criteria. Socio-demographic characteristics and past history were also collected. Results: Dementia prevalence was 36.7% in those living in NHs and VCHs, much higher than that of normal population and the prevalence of MCI was 13.3% which was the same as in normal population. Dementia was associated with old age, female, low education level and living in NHs. Men had significantly higher prevalence odds for MCI. Very old age, living in NHs and severe ADL impairment were correlated with higher prevalence odds for dementia and MCI. Conclusion: The prevalence of dementia in the elderly living in groups in Xi'an was high, especially living in NHs. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved.

1. Introduction China may have the largest amount of demented elderly people in the world. By 2005 there were 144,000,000 people over sixty in China and that number accounted 11% of total population. It was estimated that there were 3.1 million elderly individuals with Alzheimer's disease (AD) and 1.4 million with vascular dementia (VaD) in China in 1999 [1]. With increasing age dementia is gradually an important issue. Major characteristics of dementia are memory loss, difficulty in learning new knowledge, and decline in activities of daily living function. MCI is also an emerging interesting topic and a transient status between normal aging and dementia. People with MCI develop dementia at a rate of 10–15% per year, while the rate for healthy controls is 1–2% per year [2]. What is more, there were greater risk of other negative outcomes such as death and institutionalization in elderly persons with dementia and MCI [3]. Because dementia is a symptom, it can be hard to treat ⁎ Corresponding author at: 277# Yanta West Road, Department of Neurology, the First Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi'an 710061, Shaanxi, China. Tel.: + 86 29 8532 4133; fax: + 86 29 8532 4083. E-mail address: [email protected] (F. Guo).

for its broad spectra. So it is very difficult to start some form of treatment once the onset of dementia has been realized. For MCI has been thought as potential prodromal dementia, it is beneficial to be discriminated from high risk aged people, which therefore would be the start point for preventive treatment for dementia. The epidemiological study on dementia in mainland China began in 1980s. Some studies estimated the prevalence of dementia varied from 1.13% [4] to 17.22% [5]. Different diagnostic criteria and sample characteristics most likely made the difference. According to Zhang and her colleagues, dementia prevalence in Beijing, China was 7.2% in persons 65 years or older [6], AD prevalence was 4.8% and VaD 1.1% among the whole country [1]. The prevalence rates for MCI ranged from 2.4% [7] to 35.88% [8]. One of China's traditional values is that multi-generation family households are one of the main living arrangements for the elderly, especially for the oldest old. With the one child policy, more and more old men will live in NHs. According to China National Committee on Ageing, the main reasons for old people to choose nursing homes were incapable of children to care for elderly people, better to stay in nursing homes than their own homes and not willing to bother their children. The relevant actual contribution percentages were 44%, 39 and 16% respectively. There are different reasons for an elderly to choose specific nursing home, including cheaper price, good service, excellent living condition and close to his

0022-510X/$ – see front matter. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.jns.2011.08.026

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M. Guo et al. / Journal of the Neurological Sciences 312 (2012) 39–44

home, counted 50%, 24%, 18 and 8% correspondingly. While there were poor data on dementia and MCI prevalence in elderly living in groups such as NHs and VCHs in China. In the present study, dementia and MCI prevalence were investigated in several NHs and VCHs in Xi'an city.

2. Participants and methods 2.1. Sampling methods Our sample was drawn according to cluster sampling design and geographical distribution. Using tables of random numbers, there were 4 out of 73 NHs and 2 out of 55 VCHs selected in Xi'an city, which lies in the part China. The sample size was estimated by dementia and MCI prevalence. Our study was carried out between June 2008 and January 2009.

2.2. Participants All the participants were yellow race, aged 65 years or older and should stay more than 3 months. People with severe psychiatric disorders, poor hearing and vision were excluded. A structured interview was administrated to all participants including demographic information. Their medical records were reviewed for medical history, such as chronic disease, family history of dementia, injury and fracture. General physical examination involved vital signs, height and weight. Neurological physical examination focused on weakness, loss of sensation, signs of parkinsonism, cerebellar abnormalities, standing and walking with reasonable stability. Well trained research neuropsychologists performed related assessment.

2.3. Definitions Clinical diagnosis of dementia was made according to DSM-III-R criteria [9]. Cutoff points of Chinese version of the MMSE(C-MMSE) for illiterate, primary school and secondary school (and above) were ≤17, 20 and 24. Cutoff points of HDS were ≤16, 20 and 24 respectively. For the evaluation of MCI, the diagnostic criteria proposed by Petersen [2] were applied. MCI diagnosis: (1) memory complaint, (2)ADL b 22 (20 items), (3) normal general cognitive function, A: MMSE 18–26, cutoff points for illiterate, primary school and secondary school (and above) were ≤19, 22 and 26 respectively. B: HDS 17–30, cutoff point N16, 20 and 24 respectively. C: Related points should be higher than dementia cutoff points (4) course of cognitive impairment was over three months. In following neuropsychological tests administered by neuropsychologists, MMSE and HDS were used for the evaluation of different cognitive domains. ADL was performed as an index to assess physical function of participants. 140/90 mm Hg or higher is high blood pressure. At each visit, participants were seated quietly for 5 min before blood pressure was measured. BP was measured 3 times with a mercury sphygmomanometer by skilled, trained nurses after subjects had a 10-minute period of comfortable, seated rest, and these measurements were averaged. 126 mg/dL or greater was considered to have diabetes mellitus. Confirmed diagnosis of myocardial infarction, unstable angina, admission for percutaneous coronary intervention and acute coronary bypass were diagnosed with coronary heart disease (CHD). Major stroke was defined as a new neurologic deficit that persists beyond 30 days and increased by the National Institutes of Health stroke scale by ≥4. Strokes not meeting this definition were categorized as minor. Economic status was divided into three categories, poor, average and rich, which were defined as those people who had an annual income less than CNY 12,000, 12,000–36,000 and over 36,000/per person, respectively. ADL scores of less than 22, 22–40 and over 40 were cutoff points for normal, mild impairment and severe impairment.

2.4. Measurement of C-MMSE, HDS and ADL The MMSE was chosen because it has become one of the most widely used cognitive screening instruments for dementia, which is composed of 19 questions and has a maximum score of 30 points. It covers various areas of cognitive domains (orientation, memory, attention, language and visual construction, etc.) [10]. C-MMSE was used in this study [11]. HDS was firstly published in 1974, which contains 11 items and can be finished in less than 10 min [12]. The HDS has been introduced into China earlier than MMSE and used exclusively in East Asian countries till now [13]. It is well-known to us that both tests are useful for detecting AD. However HDS was testified to be more succinct, faster than MMSE and characterized by eastern social and cultural background [14]. Level of physical activity was assessed using Katz' Index of Independence in ADL Scale and Lawton and Brody's IADL Scale [15,16]. Both scales have been widely used in the literature, which was later edited by Elena Yu and William Liu according to the Chinese situation [17]. This edited ADL scale includes 20 items and its reliability and validity have been verified in elderly Chinese people [18]. Interviewers completed pilot interviews in an outpatient clinic before the study started. Inter-rater reliability coefficients (correlations) of the C-MMSE and other cognitive tests for all interviewers exceeded 0.90. 2.5. Study design This study was divided into two phases: a screening phase for all the eligible participants and a second phase for the confirmation of the suspected cases of dementia. A screening phase included personal interview on demographic information, medical history and clinical physical examination. Cognitive status was evaluated with MMSE and HDS. Physical condition of the geriatric period was evaluated with ADL. A second phase, for the ascertainment of clinical suspected cases of dementia only, another specialist (neurologist or geriatrician) visited patients and made diagnosis for the second time three months later. 2.6. Statistical analyses The chi square test was used to describe the frequency distribution and the comparison of the different prevalence. Risk factors of dementia and MCI were analyzed using monovariable and multivariable logistic regression, from which the odds ratios and 95% confidence intervals were analyzed. Cumulative logit model was also used. A p-value b0.05 indicated statistical significance. Data were analyzed using SPSS V 16.0. 3. Results 3.1. Socio-demographic characteristics of participants The total number was 264, among which 134 were males and 130 were females. Participant mean age was 77.80 ± 6.79 (range 65–103) and mean education 6.9 years. Fig. 1 summarizes the flow of participants in this study. The major socio-demographic characteristics of the study population were shown in Table 1. 3.2. Medical history Among those 264 participants, 197 subjects got chronic disease, among which 97 suffered from hypertension, 65 CHD, 56 stroke and 1 tumor. One third had more than 2 types of diseases. Stroke was more common in NHs, while participants in VCHs had more opportunity to have hypertension. 16 subjects had a family history of dementia, mostly father or mother.

M. Guo et al. / Journal of the Neurological Sciences 312 (2012) 39–44

Baseline Jan. 2008

41

Registered population on Jan. 1st , 2008 n=318

Participants n=264

Nonpaticipants n= 54 Refusals n= 38 Deceased n=12 Not found n=4

MMSE ≤ 26 or HDS < 31 n=155

MMSE>26 and HDS≥31 n=109

Normal n=23

MCI n=35

Dementia n=97

Cognitively normal n=132 Dementia n=89 Deceased n=5 Non-Dementia n=2 Unclassifiable n=1

Follow-up Dementia diagnosis 3 month later

Fig. 1. Study flow diagram.

levels and residence. Prevalence of dementia and MCI by age group, gender, education level, residence is listed in Table 2.

3.3. Prevalence of dementia and MCI The prevalence of dementia estimated according to DSM-III-R was 36.7%. There was a sharp rise in the prevalence of dementia with age, ranging from 28.0% in the age category 65–74 to 69.2% 85 years or older. Demented subjects aged 65–103, average 79.6 ± 11.2 and average education was 4.9 years. The overall dementia prevalence for men was lower than for women (29.9% versus 43.8%). Low education level was associated with higher dementia risk than in high level. What is more, the prevalence of dementia was higher in NHs than in VCHs (5.0% versus 56.4%). MCI was diagnosed in 35 of 264 participants. The prevalence of MCI was 13.3% (19 M and 16 F). Participants of MCI aged 65–89, average 77.4 ± 5.39 and average education was 8.7 years. The overall MCI prevalence for men was higher than for women (14.2% versus 12.3%). No difference was found between different age categories, education

134(50.8) 130(49.2)

After monovariable logistic regression analysis, the oldest old group, female, living in NHs, moderate and severe ADL dysfunction, poor and single were found to be predictors of dementia and MCI prevalence. Among those, living in NHs was the strongest predictor for dementia and MCI (OR 9.407, 95% CI 5.286–16.740). There were no significant diabetes mellitus, stroke and family history effects observed for dementia and MCI odds. Education level was related to lower dementia and MCI prevalence. There was significant difference between the group with the highest education (6 years or more) and illiterate (OR 0.435, 95% CI 0.247–0.762). Hypertension and CHD on the contrary seemed to be significantly lower dementia and MCI prevalence odds (OR 0.542, 95% CI 0.333–0.883; OR 0.483, 95% CI 0.216–0.846 respectively). Multivariable logistic regression analysis found that very old age, living in NHs and severe ADL impairment were correlated with higher prevalence odds for dementia and MCI. Results of the monovariable and multivariable logistic regression models for dementia and MCI were shown in Tables 3 and 4, respectively.

82(31.1) 130(49.2) 52(19.7)

Table 2 Subgroup of prevalence of dementia and MCI.

Table 1 Main socio-demographic characteristics of the study population. Characteristics Gender Male Female Age category (years) 65–74 75–84 85~ Education (years) 0 1–5 ≥6 Economic status Poor Average Wealthy Marital status Married Single Residence VCHs NHs Dementia family history No Yes

3.4. Risk factors of dementia and MCI

Total (N = 264)

63(23.9) 48(18.2) 153(58.0) 38(14.4) 112(42.4) 114(43.2) 125(47.3) 139 (52.7) 101(38.3) 163(61.7) 248(93.9) 16(6.1)

Subgroup Age 65~ 75~ 85~ Gender Male Female Education 0 1–5 ≥6 Residence VCHs NHs

N

Dementia N P (%)

χ2

P value

MCI N P (%)

χ2

P value

82 130 52

23(28.0) 38(29.2) 36(69.2)

29.437

0.000

8(9.8) 22(16.9) 5(9.6)

2.993

0.224

134 130

40(29.9) 57(43.8)

5.561

0.018

19(14.2) 16(12.3)

7.400

0.025

63 48 153

33(52.4) 20(41.7) 44(28.8)

11.326

0.003

6(9.5) 4(8.3) 25(16.3)

3.040

0.219

101 163

5(5.0) 92(56.4)

71.136

0.000

17(16.8) 18(11.0)

1.817

0.178

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M. Guo et al. / Journal of the Neurological Sciences 312 (2012) 39–44

4. Discussion

Table 4 Multivariable logistic regression analysis of risk factors of dementia and MCI.

In the world, the population of people aged 60 years and older is expected to increase from 605 million in 2000 to 1.2 billion by 2025 and 2 billion by 2050. About two-thirds of all older people live in the developing world and this will increase to 75% by 2025 [19]. Seitz reviewed 30 studies on the prevalence of dementia of older adults in long-term care. The estimated prevalence in NHs varied between 12.0% [20] and 95% [21] with a median prevalence of dementia of 58% from all the studies [22]. The prevalence of dementia was 36.7% in elderly living in NHs and VCHs in Xi'an, which was similar with them. In our sample group, we found a sharp rise in the prevalence of dementia with age, ranging from 28.0% in the age category 65–74 to 69.2% 85 years or older. We had the same result with the United States [23], Europe [24] and also other studies from China [25]. In a word, aging is the most important risk factor for dementia across various ethnic groups. There were significant gender differences in prevalence odds between men and women. Our data showed the prevalence of dementia was significantly higher in women than men (43.8% versus 29.9%, P = 0.018). In one Chinese epidemiological study, significant gender differences were found that higher prevalence was in women than men (pOR age-adj = 1.9, 95% CI 1.4–2.4) for AD. On the other hand, the prevalence of VaD was on average lower for women than men, while no significant difference was found [26]. A Dutch followup study confirmed this result and thought that the protective effect

Risk factors

Subgroup

Age

65–74 (ref.) 75–84 85~ VCHs (ref.) NHs Normal (ref.) Mild impairment Severe impairment

Residence ADL

P value

OR

95% CI

0.460 0.007

1.254 2.960

0.688–2.283 1.354–6.473

b 0.001

5.484

2.758–10.905

0.635 0.032

0.830 2.188

0.386–1.788 1.070–4.477

Ref. = Reference category, ADL indicates Activities of Daily Living.

of estrogen for premenopausal women and earlier death for men from cardiovascular disease may explain these results [27]. Kalaria and colleagues reviewed studies in Latin America, Africa, and Asia. They confirmed that women are marginally more likely to develop dementia, particularly in very old age, on the basis of the greater expected numbers of aging women [28]. As the association between sex and risk of dementia to be concerned, lifestyle, ethnicity, sex steroid hormones and genetic polymorphisms of sex-related genes should be taken into account, which would complicate this association [29]. On the contrary, the association between sex and risk of dementia was not significant in Italian [30] and Spanish [31] populations. Our result showed that low education level was associated with higher dementia risk than in high level, which was confirmed by

Table 3 Monovariable logistic regression analysis of risk factors of dementia and MCI. Independent variables and effects Age 65~ (ref.) 75~ 85~ Gender Male (ref.) Female Education, years 0 (ref.) 1–5 ≥6 Residence VCHs (ref.) NHs ADL Normal (ref.) Mild impairment Severe impairment Economic status Wealthy (ref.) Average Poor Marital status Married (ref.) Single Hypertension No (ref.) Yes CHD No (ref.) Yes DM No (ref.) Yes Stroke No (ref.) Yes Family history No (ref.) Yes

Wald-χ2

P value

OR

95% CI

51(38.7) 70(53.0) 11(8.3)

0.808 24.676

0.369 0.000

1.284 6.304

0.744–2.215 3.049–13.034

19(54.3) 16(45.7)

75(56.8) 57(43.2)

5.156

0.023

1.713

1.076–2.725

33(34.0) 20(20.6) 44(45.4)

6(17.1) 4(11.4) 25(71.4)

24(18.2) 24(18.2) 84(63.6)

1.754 8.353

0.185 0.004

0.617 0.435

0.302–1.261 0.247–0.762

101 163

5(5.2) 92(94.8)

17(48.5) 18(51.5)

79(59.9) 53(40.1)

58.105

0.000

9.407

5.286–16.740

97 62 105

14(14.4) 18(18.6) 65(67.0)

14(40.0) 10(28.6) 11(31.4)

69(52.3) 34(25.7) 29(22.0)

4.854 45.530

0.028 0.000

2.079 7.603

1.084–3.989 4.218–13.705

114 112 38

32(33.0) 44(45.4) 21(21.6)

18(51.4) 14(40.0) 3(8.6)

64(48.5) 54(40.9) 14(10.6)

2.276 7.618

0.131 0.007

1.473 2.641

0.891–2.436 1.297–5.377

125 139

24(24.7) 93(75.3)

22(62.9) 13(37.1)

79(59.9) 53(40.1)

24.591

0.000

3.396

2.095–5.505

167 97

71(73.2) 26(26.8)

21(60.0) 14(40.0)

75(56.8) 57(43.2)

6.043

0.014

0.542

0.333–0.883

199 65

83(85.6) 14(14.4)

24(68.6) 11(31.4)

92(69.7) 40(30.3)

6.477

0.011

0.483

0.216–0.846

227 37

83(85.6) 14(14.4)

30(85.7) 5(14.3)

114(86.4) 18(13.6)

0.031

0.860

1.061

0.547–2.057

208 56

73(75.3) 24(24.7)

27(77.1) 8(22.9)

108(81.8) 24(18.2)

1.469

0.226

1.414

0.807–2.478

248 16

91(93.8) 6(6.2)

33(94.3) 2(5.7)

125(94.7) 7(5.3)

0.350

0.554

1.335

0.512–3.482

N

Dementia (n = 97)

MCI (n = 35)

82 130 52

23(23.7) 38(39.2) 36(37.1)

8(22.8) 22(62.9) 5(14.3)

134 130

40(41.2) 57(58.8)

63 48 153

Normal control (n = 132)

Ref. = Reference category. ADL indicates Activities of Daily Living; CHD, coronary heart disease; DM, diabetes mellitus.

M. Guo et al. / Journal of the Neurological Sciences 312 (2012) 39–44

Shadlen and colleagues [32]. They did a study in the United States and found that low education level (≤10 years) had twice the risk of dementia as high education level in Caucasians (N10 years). Another Chinese study revealed that educated persons had significantly lower AD prevalence after adjustment for age. No significant educational effects were observed for VaD [26]. In terms of education level and risk of dementia, socioeconomic status and sex should be concerned, which would perplex the relationship [29]. For the first time, we found that the prevalence of dementia was much higher in NHs than VCHs in Xi'an. It is for the reason that firstly cognitive impairment was a key precursor for institutionalization into NHs [33]. Institutionalization is considered a key clinical marker of dementia progression [34]. Secondly NHs provided accommodation from Xi'an city and villages nearby wider than VCHs, which accepted old men only retired from the army. Ordinarily speaking, soldiers are in good physical health and receive more health care. Thirdly doctors and nurses in NHs were insufficient and nursing techniques were limited, as comorbidity conditions were so common in NHs, such as hypertension, CHD, DM and stroke. If such diseases were poorly controlled, the incidence of dementia would increase. We did not find older age, lower education were associated with MCI, the same with the Eugeria study [35], yet most other studies didn't [36,37]. While African American race, depression, presence of apolipoprotein E ε4 allele (APOE-4), cortical atrophy, and MRI identified infarcts were associated with high MCI prevalence in the CHS Cognition Study [36] and the Cardiovascular Health Study [38]. What is more midlife hypercholesterolemia and systolic blood pressure elevation were also remained risk factors for MCI [39]. There was a rare finding in our study that the prevalence of MCI for men was higher than for women (14.2% versus 12.3%), which was in accordance with the Pennsylvania cohort study [40]. We believed that it was because of male majority in our cohort while the number of females was more than males in most studies, and relative small study sample. Our data showed severe ADL dysfunction was correlated with higher prevalence odds for dementia and MCI. According to MCI definition and our diagnosis criteria for MCI, ADL b22, we believed that dementia contributed most to this result. The finding was in accordance with Chan et al., who reported more than half of those classified as having dementia were in fair or poor physical health status. While 37.2% had IADL difficulties only and 44.1% had at least one ADL difficulty. They also reported that MCI patients had better physical functioning compare to dementia [41]. Dementia and MCI were different heterogeneous entities because different types of MCI developed different types of dementia, such as amnestic MCI to AD, non-amnestic MCI (single domain) to frontotemporal dementia, amnestic and non-amnestic MCI (multiple domain) to vascular dementia, non-amnestic MCI (multiple domain) to dementia with Lewy bodies [42]. Furthermore some MCI patients would convert to normal people. On the other hand, MCI could be considered potential prodromal dementia. From the view of prevention, why couldn't we treat them as a whole thing? In the light of our results, very old age, living in NHs and severe ADL impairment remained risk factors for dementia and MCI. Aging is the most important risk factor for dementia and MCI which we couldn't avoid it. The government should think the policy over to increase budgets, so that NHs could have better medical techniques and equipment. The accommodation in NHs for the elderly would be more effective. Dementia and MCI may lead to ADL dysfunction and severe ADL damage would aggravate the course of dementia and MCI. One major shortcoming of our studies was that we did not distinguish AD, VaD from dementia and the sample size was rather small. Another point, we defined ADL b22 as one of selection criteria for MCI. We may risk the possibility of losing MCI patients who had physical dysfunctions. Graham and colleagues pointed out 15.9%, 13.9 and 3.3% of cognitive impairment, no dementia (CIND) patients had mild, moderate

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