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IPA Bulletin

An Overview of Research into Age-Related Dementia in China

Y.C. Shen, G. Li, Y.T. Li, C.H. Chen, S.R. Li, Y.W. Zhao, and W.X. Zhang

Since the early 1980s, the proportion of elderly people in the general population of China has been increasing rapidly, and dementia is becoming a major public health problem. However, few prevalence rate reports have been published, and no incidence rate of dementia in China was available until 1986. An epidemiological program was initiated by our institute in 1986 to investigate age-related dementia in an urban community in Beijing. Three years later, a cohort of aged people was again studied to obtain the incidence of age-related dementia and the characteristics of its distribution. A case-control study was conducted in 1989 to assess the possible risk factors associated with Alzheimer's disease among the Chinese population.

Prevalence of Age-Related Dementia in an Urban Area of Beijing
The Mini-Mental State Examination (MMSE) was translated into Chinese and pretested in a clinical sample. A score of 17 was identified as the cut-off point for moderate and severe dementia, with sensitivity 1.0 and specificity 0.98. It was found that MMSE scores were influenced in particular by the educational level of elderly people. Of the total sample of 1,331, 1,090 elderly people (age 60 or older) completed the examination. A two-phase procedure was employed: (a) using MMSE to screen out the potentially demented cases; and (b) following up by a clinical evaluation, conducted by psychiatrists using the cognitive part of the Geriatric Mental State, and by diagnosis by psychiatrists using DSM-III diagnostic criteria for dementia and the Dementia Differential Diagnostic Schedule (DDDS). The prevalence rate of moderate and severe dementia was 1.28% for those age 60 or over and 1.82% for those age 65 or over. When the Chinese age-specific rates were adjusted as to the percentage of elderly persons in the U.S. population in 1984, the prevalence rate became 3.2% for those age 65 or over. This prevalence rate increased sharply to 10.67% for those age 80 or over. The rate for females (1.88%) was slightly higher than that for males (0.59%). In our data, the rate of multi-infarct dementia (0.73%) was much higher than that of primary degenerative dementia (0.27%).

When the sample was extended to 5,172 people ages 60 and over in the same urban district, no significant differences in prevalence rates was found between the first cohort and the extended cohort.

A 3-Year Follow-Up Study
Three years later, the 1,090 subjects were evaluated by the same psychiatrists with the same instruments. Among the 825 subjects reexamined, seven new cases were found of moderate or severe dementia and six new cases were found of mild or possible dementia. The average annual incidence rate of moderate and severe dementia for those age 60 or over was 0.3% (95%, confidence interval 0.08%-0.52%). When the six mild or possible cases were included, the corresponding rate was 0.56% (95%, confidence interval 0.26%-0.86%). The incidence of dementia also increased sharply with age; in the 60-69 age group, it was 0.07%, while in the 80 and over group, it was 2.5%. Multi-infarct dementia was more common than primary degenerative dementia, with a ratio of 3:2. The average duration of dementia in this study was 8.0 years (SD = 3.4). The risk of death for demented patients was 3 times higher than for the entire cohort (standardized mortality rate = 2.95).

Our data also showed that elderly people with less education, a long history of unemployment, limited physical activity, and a history of stroke may have higher risk for dementia.

A Case-Control Study of Risk Factors for Alzheimer's Disease
Ten psychiatric hospitals in northern and eastern China collaborated on a case-control study to assess the possible risk factors associated with AlzheimerÕs disease (AD). The study involved 126 clinically diagnosed AD patients and a control group of 252 undemented people matched by sex, age, and nationality. Through conditional logistic regression analysis, a major affect model of risk factors of AD showed that the major risk factors were family history of dementia in the parents, psychoses among the first-degree relatives, few interests, and more frequent severe life events during the person's lifetime.

The Psychological Well-Being of Relative Caregivers
The psychological well-being of 131 relative caregivers of 50 patients with senile dementia was compared with that of 288 relative caregivers for 102 nondemented elderly people, using GreeneÕs RelativeÕs Stress Scale (RSS) and Symptom Checklist-90 (SCL-90). The caregivers of the dementia group (DCG) were observed with total scores of 9.4 on the RSS, which was much higher than the scores of 2 for the group caring for the nondemented group (NDCG)(p 0.01). The same tendency was found in the stress-related items of SCL-90 scoring between DCG and NDCG: 0.319 versus 0.232 (p 0.01).

The significant variables contributing to psychological well-being were found to be psychological stress level, sex, education, age, family income, and family size. The authors urge that more attention be paid to the mental health service and to support for those caring for elderly people with dementia, as presently the majority of elderly dementia patients are cared for at home by their relatives in the community.

Y.C. Shen, G. Li, Y.T. Li, C.H. Chen, S.R. Li, Y.W. Zhao, and W.X. Zhang
Institute of Mental Health
Beijing Medical University
Beijing, China

Suggested Readings
Chen, C.H., et al. (1992). An epidemiological survey of dementia in the aged population of a western urban district of Beijing. Chinese Mental Health, 6, 49-52.

Li, G., et al. (1988). Preliminary application of MMSE in the aged of urban population in Beijing. Chinese Mental Health Journal, 2, 13-18.

Li., G., et al. (1989). An epidemiological survey of age-related dementia in an urban area of Beijing. Acta Psychiatrica Scandinavica, 79, 557-563.

Li, G., et al. (1991). A three-year follow-up study of age-related dementia in an urban area of Beijing. Acta Psychiatrica Scandinavica, 83, 99-103.

Li, G., et al. (1992). A case-control study of AlzheimerÕs disease in China. Neurology, 42, 1481-1488.

Li, Y.T., et al. (1990). Caring for senile dementia affecting the psychological well-being of relative caregivers. Chinese Mental Health Journal, 4, 1-6.

Shen, Y.C., et al. (1992). A case-control study of risk factors in Alzheimer's disease. Chinese Journal of Neurology and Psychiatry, 25, 284-287.

Shen, Y.C., et al. (1994). Epidemiology of age-related dementia in China. Chinese Medical Journal, 101, 60-64. l

This article appeared in IPA Bulletin, Volume 13, Number 1