Prevalence of dementia and its correlates among participants in the National Early Dementia Detection Program during 2006-2009.
ABSTRACT To investigate the prevalence of dementia and its correlates among people with poor socioeconomic status, poor social support systems, and poor performance on the Korean version of the Mini-Mental Status Exam (MMSE-KC).
We used 2006-2009 data of the National Early Dementia Detection Program (NEDDP) conducted on Jeju Island. This program included all residents >65 years old who were receiving financial assistance. We examined those who performed poorly (standard deviation from the norm of <-1.5) on the MMSE-KC administered as part of the NEDDP, using age-, gender-, and education-adjusted norms for Korean elders. A total of 1708 people were included in this category.
The prevalence of dementia in this group was 20.5%. Multivariate logistic regression analysis revealed that the following factors were statistically significantly associated with dementia: age of 80 or older, no education, nursing home residence, and depression.
The prevalence of dementia is very high among those with lower MMSE-KC scores, and significant correlates include older age, no education, living in a nursing home, and depression. Enhancing lifetime education to improve individuals' cognitive reserves by providing intellectually challenging activities, encouraging living at home rather than in a nursing home, and preventing and treating depression in its early phase could reduce the prevalence of dementia in this population.
- SourceAvailable from: aphapublications.org[show abstract] [hide abstract]
ABSTRACT: OBJECTIVEs. An earlier paper estimated the per-case and national incidence costs of Alzheimer's disease for 1983. This paper updates the estimates of costs per case to 1991 and presents new national prevalence estimates of the economic and social costs of the disease. All data for the cost estimates were taken from published sources or provided by other researchers. At midrange values of the estimated cost and epidemiological parameters, the discounted (at 4%) direct and total costs of Alzheimer's disease were $47,581 and $173,932 per case, respectively. The estimated 1991 national direct and total prevalence costs were $20.6 billion and $67.3 billion, respectively. Assuming conservatively that the prevalence of the disease remains constant, the estimated discounted present values of the direct and total costs of all current and future generations of Alzheimer's patients are $536 billion and $1.75 trillion, respectively. The $536 billion and $1.75 trillion figures are minimum estimates of the long-term dollar losses to the US economy in 1991 caused by Alzheimer's disease.American Journal of Public Health 09/1994; 84(8):1261-4. · 3.93 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Caring for elderly people with dementia is associated with well-documented increases in burden, distress, and decrements in mental health and wellbeing. More severe behavioural, cognitive, and functional impairments in a patient are associated with higher levels of burden and distress. Distress increases with care hours per week, number of tasks, and declining coping and support resources. Demographic factors also affect levels of burden and distress. Promising, evidence-based interventions exist, but substantial economic and policy barriers preclude their widespread dissemination. Health-care policy makers should consider addressing these barriers; clinicians and families must campaign for reimbursement; and clinical researchers must develop more potent preventive interventions. In this article we review how dementia care affects the mental health of the carer and identify interventions that might be useful in mitigating carer burden and distress.The Lancet Neurology 12/2006; 5(11):961-73. · 23.92 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Most studies on caregiver burden have been conducted in Western countries, while few studies on the correlates of caregiver burden have been performed in Korea. To suggest better policies for the care of dementia patients by using a nationwide database to identify factors that affect caregiver burden in Korea. The database of the Korean National Health Insurance (KNHI) and National Medical Aid (NMA) programs, which covers all Koreans, was used. A sample of 609 dementia patients and their caregivers was selected from a total of 85,281 dementia patients in 2004 and interviewed to evaluate the total cost of care and caregiver burden. Stepwise multiple linear regression analysis was then performed to identify significant independent predictors of caregiver burden. Among caregiver-related factors, caregiver burden was higher in those who were female, had a history of home care during the previous year, and had less education. Among patient-related factors, poor ADL/IADL function was significant. The most interesting result was that subjective sense of socioeconomic status (good/fair/poor) was a stronger predictor of caregiver outcome than actual economic costs. The results of this study suggest that interventions to assist patients with dementia should focus on female caregivers, especially those considered likely to be suffering from an economic burden. Interventions should also aim to improve the ADL and IADL capacities of patients.Gerontology 12/2008; 55(1):106-13. · 2.68 Impact Factor
Korea has a rapidly aging society due to a low birth rate and
increasing longevity. The proportion of Koreans over the age
of 65 years was 7.2% in 2000 and 9.1% in 2005.1 In addition, es-
134 Copyright © 2012 Korean Neuropsychiatric Association
timates based on population data predict that 14.5% of Kore-
ans will be over the age of 65 years by 2018 and that by 2026,
the percentage will be 20.8%.2 The speed at which Korean so-
ciety is aging is much more rapid than that of any other devel-
oped country,3 and it is projected to be among the fastest in the
world. Korea will replace Italy as having the world’s second
highest proportion of elderly by 2050.
Due to this rapidly aging population and the progressive
Westernization of lifestyles in Korea, dementia has emerged as
a major health problem in Korea.4,5 Estimates of the prevalence
of dementia in Korea range from 7.0% to 13.1%.3,6-9 Recently,
Kim et al.9 predicted that the number of dementia patients will
double every 20 years until 2050 in Korea and the dementia pa-
Prevalence of Dementia and Its Correlates
among Participants in the National Early Dementia
Detection Program during 2006-2009
Moon-Doo Kim1 , Joon-Hyuk Park1, Chang-In Lee1, Na-Ri Kang1, Jae-Sung Ryu1,
Bong-Hee Jeon1, Ki-Woong Kim2, Won-Myong Bahk3, Bo-Hyun Yoon4,
Seunghee Won5, Jun Hwa Lee6, Duk-Soo Kim7 and Seong-Chul Hong8
1Department of Psychiatry and Institute of Medical Science, Jeju National University School of Medicine, Jeju, Korea
2Department of Neuropsychiatry, Seoul National University Bundang Hospital, Seongnam, Korea
3Department of Psychiatry, College of Medicine, The Catholic University of Korea, Seoul, Korea
4Department of Psychiatry, Naju National Hospital, Naju, Korea
5Department of Psychiatry, Kyungpook National University Hospital, Daegu, Korea
6Department of Pediatrics, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
7Department of Chemistry, Jeju National University College of Natural Science, Jeju, Korea
8Departments of Preventive Medicine and Institute of Medical Science, Jeju National University School of Medicine, Jeju, Korea
ObjectiveaaTo investigate the prevalence of dementia and its correlates among people with poor socioeconomic status, poor social sup-
port systems, and poor performance on the Korean version of the Mini-Mental Status Exam (MMSE-KC).
MethodsaaWe used 2006-2009 data of the National Early Dementia Detection Program (NEDDP) conducted on Jeju Island. This program
included all residents >65 years old who were receiving financial assistance. We examined those who performed poorly (standard deviation
from the norm of <-1.5) on the MMSE-KC administered as part of the NEDDP, using age-, gender-, and education-adjusted norms for Ko-
rean elders. A total of 1708 people were included in this category.
ResultsaaThe prevalence of dementia in this group was 20.5%. Multivariate logistic regression analysis revealed that the following factors
were statistically significantly associated with dementia: age of 80 or older, no education, nursing home residence, and depression.
ConclusionaaThe prevalence of dementia is very high among those with lower MMSE-KC scores, and significant correlates include older
age, no education, living in a nursing home, and depression. Enhancing lifetime education to improve individuals’ cognitive reserves by
providing intellectually challenging activities, encouraging living at home rather than in a nursing home, and preventing and treating de-
pression in its early phase could reduce the prevalence of dementia in this population.
Psychiatry Investig 2012;9:134-142
Key Wordsaa Dementia, Prevalence, Correlates, MMSE-KC.
Received: December 9, 2011 Revised: December 20, 2011
Accepted: December 30, 2011 Available online: April 30, 2012
Correspondence: Moon-Doo Kim, MD, PhD
Department of Psychiatry, Jeju National University School of Medicine, 15
Aran 13-gil, Jeju 690-756, Korea
Tel: +82-64-717-1234, Fax: +82-64-717-1849
cc This is an Open Access article distributed under the terms of the Creative Commons
Attribution Non-Commercial License (http://creativecommons.org/licenses/by-
nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduc-
tion in any medium, provided the original work is properly cited.
Print ISSN 1738-3684 / On-line ISSN 1976-3026
MD Kim et al.
tient population will skyrocket from 470000 in 2010 to 1140000
by the year 2030 and to 2130000 by the year 2050. Further-
more, they reported that the prevalence of dementia in Korea
is higher than in Western countries and in other Asian coun-
The rapid growth of the elderly population and of the popu-
lation with dementia will impose significant economic and
psychosocial burdens on caregivers and societies, likely posing
major problems. In the US alone, Alzheimer’s disease (AD),
the most frequent cause of dementia, is associated with an es-
timated health care cost of US$172 billion per year.10 The cost
of dementia in Korea was estimated at between US$3 and
US$7 billion in 2004,8 totaling 0.446-1.040% of the Korean
GDP (US$673.1 billion).11 Families of dementia patients also
suffer heavy psychological, physical, and economic burdens.12,13
To reduce these societal and individual burdens, prevention,
early detection, and early treatment may be the most important
steps to take. Many studies designed to identify risk factors and
correlates of dementia and programs for the early detection and
treatment of dementia patients in the general population have
been reported. But few, if any, have addressed the portion of the
aging population characterized by low socioeconomic status
and poor cognitive function (as assessed, for example, by low
scores on the Korean version of the Mini-Mental Status Exam,
MMSE-KC), who are often at high risk for dementia.
This group is very important because they are on the verge of
developing dementia. Preventing dementia in this group is, in
a sense, more important than addressing it among the general
population. Therefore, we investigated the prevalence of demen-
tia and its correlates among people of low socioeconomic sta-
tus and with poor social support systems who live on Jeju Is-
Jeju Island has some advantages for the study of dementia
because of the restricted interchange of its population with the
mainland. In addition, the island has a greater proportion of
aged individuals (10.4% of the total population in 2005 were
over 65 years of age), with those over 80 years of age compris-
ing 8.0% of the total aged population, the highest among all
provinces of Korea.1
Subjects and research period
We used 2006-2009 Jeju Island data from the National Early
Dementia Detection Program (NEDDP), which covers all of the
economically poor elderly living on Jeju island. This program
included all of the residents over the age of 65 who were recipi-
ents of financial assistance programs. In 2009, this population
included about 5000 people.
This study examined those who showed poor performance
[standard deviation (SD) from the norm of <-1.5] on the
MMSE-KC,14 administered through the NEDDP, using age-,
gender-, and education-adjusted norms for Korean elders.15
All who agreed to participate in this research were included,
resulting in a total of 1708 participants. This study was ap-
proved by the Institutional Review Board at Jeju National Uni-
versity Hospital, Jeju, Korea.
A semi-structured interview addressing demographic char-
acteristics (age, sex, education, residence, living arrangement,
marital status, economic status, etc.) and history of head trau-
ma, presence of depression, and number of medical illnesses
was conducted. If the participant alone could not give enough
information, reliable informants (spouse, child, other relatives,
and close friends, in that order) were interviewed as well.
Diagnosis of dementia
Dementia was defined according to the diagnostic criteria of
the Diagnostic and Statistical Manual of Mental Disorders,
Fourth Edition (DSM-IV).16
A face-to-face standardized diagnostic interview and physi-
cal and neurological examinations were administered to each
subject using the Korean version of the Consortium to Estab-
lish a Registry for Alzheimer’s Disease Assessment Packet
(CERAD-K) and Clinical Assessment Battery (CERAD-K-C).14
Geriatric psychiatrists, who were certified in CERAD-K Clini-
cal Assessment Battery (CERAD-K-C) administration by the
CERAD-K headquarters, administered the tests. The CERAD-
K Neuropsychological Assessment Battery (CERAD-K-N)14,15
was also administered by neuropsychologists or trained research
nurses. The CERAD-K-N consists of nine neuropsychological
tests: the verbal fluency test, 15-item Boston Naming Test,
MMSE-KC, word-list memory test, constructional praxis test,
word-list recall test, word-list recognition test, constructional
recall test, and trail-making test. All instruments were validat-
ed in the Korean population. We did not classify subtypes of de-
mentia due to the large number of subjects and the screening
nature of the NEDDP.
Diagnosis of depression
The Korean version of the Geriatric Depression-Scale Short
form (SGDS-K)17 was used to screen for depression. Final di-
agnosis was made by two psychiatrists according to DSM-IV
We identified the prevalence of dementia among these sub-
136 Psychiatry Investig 2012;9:134-142
Dementia among Poor MMSE-KC Performance
jects according to each factor: age, sex, education, residence, liv-
ing arrangement, marital status, economic status, presence of
head trauma, presence of depression, and number of medical
We then performed multiple logistic regression analysis us-
ing the statistically significant independent variables, with de-
mentia as the dependent variable. We determined the odds ra-
tio (OR) and 95% confidence intervals (95% CI) for each of the
independent variables. SPSS (version 12.0) software was used
for all analyses, with the level of significance defined as p≤0.05.
Characteristics of participants
The sample consisted of 1708 community- and nursing home-
dwelling Koreans, including 1220 women and 488 men, with
an average age of 78 (SD=7.2) years. The overall mean years of
education was 3.3 (SD=4.2; men: 7.0, SD=4.2; women: 1.8, SD=
3.1), and the overall mean MMSE-KC score was 15.9 (SD=5.8;
men: 19.6, SD=5.2; women: 14.4, SD=5.4).
Statistically significant sex differences in age distribution, ed-
Table 1. Characteristics of participants
No of medical disease
*p<0.05, **lower than minimum cost of living, †presence of previous head trauma, with loss of consciousness exceeding 10 minutes,
‡screened by SGDS-K ≥8 and diagnosed by two psychiatrists. MMSE-KC: Mini-Mental Status Examination in the Korean Version of the
CERAD Assessment Packet
MD Kim et al.
ucation, residence, living arrangement, marital status, econom-
ic status, and presence of head trauma history (all p-values
<0.05) were found; only depression and number of medical ill-
nesses showed no sex differences (Table 1).
Prevalence and OR of dementia
We examined the prevalence of dementia according to vari-
ous levels of variables and calculated crude and age- and sex-
adjusted ORs. Of the 1708 participants who completed the
evaluation, 318 (20.5%) were diagnosed with dementia, includ-
ing 72 (17.3%) men and 246 (21.7%) women. The prevalence
was not statistically different between the sexes (p=0.055). The
prevalence of dementia showed an increasing trend by age, be-
ing 14.7% for 65- to 69-year-olds, 15.4% for 70- to 74-year-olds,
25.7% for 80- to 84-year-olds, and 28.0% for ≥85-year-olds. Re-
garding education, the prevalence of dementia was 26.6% in the
no-education group, 13.7% in the group with 1-6 years of edu-
cation, and 12.4% among those with 7 years of education and
more. The prevalence of dementia among those living in a nurs-
ing home was 46.1%, and that among subjects with a history of
head trauma and depression was 60% and 23.4%, respectively.
The 85+ years age group (OR=2.204, 95% CI 1.378-3.526)
was more likely to have dementia than the 65-69 years age group.
Those in the no-education group (OR=2.621, 95% CI 1.606-
4.277) were more likely to have dementia than those with 7 years
education or more. Persons living in a nursing home (OR=3.969,
95% CI 2.649-5.947) were more likely to have dementia than
those living with a spouse. Those who had a history of head trau-
ma (OR=6.210, 95% CI 1.022-37.744) were more likely to have
dementia than those without such a history. However, persons
with depression (OR=1.258, 95% CI 0.929-1.703) were not more
likely to have dementia than those without depression. There
were no statistically significant differences according to marital
status, residence, economic status, presence of depression, and
number of medical diseases. In summary, our univariate logis-
tic analyses indicate that older age (80-84 and ≥85 years of age),
no education, nursing home residence, and presence of head
trauma history are associated with dementia (Table 2).
Multiple logistic regression analysis
Table 3 shows the results of the multiple logistic regression
analysis. The results indicate that the following factors were
statistically significantly associated with dementia: age 80-84
(OR=2.132, 95% CI 1.163-3.908) or ≥85 years (OR=1.963, 95%
CI 1.065-3.617), no education (OR=2.078, 95% CI 1.145-3.771),
nursing home residence (OR=5.630, 95% CI 2.107-15.044), and
depression (OR=1.586, 95% CI 1.089-2.309).
Marital status, urban/rural residence, socioeconomic status,
and number of medical illnesses were not significantly correlat-
ed with dementia after controlling for the confounding influence
of age, sex, education, living arrangement, presence of depres-
sion, and number of medical illnesses.
In a previous study on the general Korean population, the
prevalence of dementia was estimated as 8.1%.9 In the present
study, which focused on a subpopulation of Korea, it was 20.5%,
much higher. This could be explained by the characteristics of
the subjects in the present study, namely, a population with a
large proportion of older persons with no formal education
(52.1%), with lower socioeconomic status, lower MMSE-KC
scores, and a larger proportion of nursing home residents
(11.6%) compared to the general population. This result is par-
tially consistent with the results from Hamid et al.18 and Wimo
et al.,19 who noted that the prevalence of dementia is 3-4 times
higher in developing countries than in developed countries.
They suggested that the lack of formal education is a major con-
tributor to higher overall dementia prevalence. Among our sub-
jects, 52.1% had no education, which is consistent with their
We included subjects who had an MMSE-KC score below
-1.5 SD of the mean compared to age-, sex-, and education-
adjusted norms for Korean elders.15 Kim et al.9 investigated the
prevalence of dementia in a nationwide Korean sample using
MMSE-KC. They assigned scores of 10% for good (-1.0 SD or
higher), 50% for intermediate (between -1.5 and -1.0 SD), and
100% for poor performance (MMSE-KC scores below -1.5 SD
of the norm) on the MMSE-KC in a phase II clinical diagnos-
tic study. In that study, of the 1673 subjects, 351 (20.98%) were
diagnosed as having dementia. Another similarly designed study
20 performed in the Seoul metropolitan area reported an inci-
dence of dementia of about 18.43%. Because our sample con-
sisted entirely of people with MMSE-KC scores lower than -1.5
SD of the norm, we could not compare these results directly,
but it is reasonable to assume that the prevalence in our popu-
lation would be similar to that in previous research.
In general, old age, female sex, lower education level, pres-
ence of depression, traumatic brain injury, and other vascular
risk factors are well-known risk factors and correlates of de-
In the present study, multivariate analysis revealed that ad-
vanced age, no education, living in a nursing home, and depres-
sion were correlated with dementia. Marital status, economic
status, and urban/rural residence were not associated with de-
mentia after controlling for age, sex, education level, depres-
sion, traumatic brain injury, and number of medical illnesses.
Age is an established risk factor for dementia, and the prev-
alence of dementia increases with age.22-24 Our results concur
with previous results, demonstrating that older age is a risk fac-
138 Psychiatry Investig 2012;9:134-142
Dementia among Poor MMSE-KC Performance
tor for dementia among those with lower MMSE-KC scores.
Many studies have found higher rates of dementia among
women.22,23,25,26 This is usually explained by a life of cumulative
social disadvantages; for example, a lack of educational oppor-
tunities in early life, which severely hinders access to employ-
ment and personal development. Lower educational attainment
and less complex occupational activities have been found to be
associated with cognitive decline and dementia risk.27,28 Our re-
sults in this area are not consistent with previous results, but
this difference could be explained by differences in the charac-
teristics of subject populations. Gender may be an important
modifier of the risk for AD, and this may be due to biological
differences,29 differences in survival rates, or cohort differenc-
es in behavior and exposure.30 Our subject population was not
a general population but a group already at risk for cognitive de-
cline (lower MMSE-KC score). Our results may also be explain-
ed by the unequal proportions of men and women and varia-
tion in their characteristics. The sample included more women.
Furthermore, men are more likely to live with their spouse than
are women, who are more likely to live alone. This means that
female subjects may have better social function than men, who
are considered dependent on their spouses throughout their
De Deyn et al.31 suggested that the higher prevalence of de-
mentia in women than in men is partly because men who are
starting to show cognitive decline may be less capable of man-
Table 2. Prevalence of dementia according to levels of variables and crude odds ratios and age and sex adjusted odds ratios
Total72 17.3 246
70-74 25 18.2 27
75-79 17 13.2 49
85+8 19.0 88
Education7 years+28 15.5 3
1-6 years26 15.1 37
None 18 28.1 205
With others6 20.0 62
Nursing home2347.9 59
Marital statusMarried 4014.9 45
Others 1324.1 13
Economic statusNot disadvantaged4 12.9 5
Head traumaNo 7016.9 245
Yes2 50.0 1100.0
213 16.9 38
3-53 16.7 10
ASOR: Age and Sex Adjusted, In case of Age: sex-adjusted odd ratio. COR: crude odd ratios, CI: confidence interval
1.2770.989 1.650 1.123 0.862 1.464
With spouse3312.7 39
1.2990.6282.6861.028 0.492 2.151
35.843 0.972 35.1200 6.210 1.022 37.744 0
1.229 0.9101.658 1.258 0.929 1.703
0 19 18.6 58
MD Kim et al.
aging their lives and therefore prefer institutionalization. As
nearly all previous epidemiological studies failed to include
residents of nursing homes, rest homes, or other specialized-
care facilities, they would have missed a portion of the popu-
lation in whom cognitive deterioration is more likely. This may
result in a gender bias, as this group may contain relatively
more men. Our study included institutionalized persons, and
this may have resulted in the contrast between our finding of
no higher dementia prevalence in women and others’ results
showing a higher prevalence. A metaanalysis done by Gao et
al.32 found gender differences in the incidence of dementia as-
sociated with AD but not in the incidence of dementia in gen-
eral. These differences are most likely explained by the fact that
men are at a higher risk than women for vascular dementia.
Table 3. Multiple logistic regression analysis of dementia and related variables
B SEWald p-valueOR
Head trauma history
Number of medical illness
3 and over
*statistically significant. OR: odds ratio, CI: confidence interval
-1.627 0.501 10.567 0.001 0.196
-0.111 0.244 0.208 0.648 0.895 0.555 1.443
-0.119 0.172 0.477 0.490 0.888 0.634 1.244
-0.431 0.405 1.132 0.287 0.650 0.293 1.438
0.417 1.273 0.107 0.744 1.517 0.125 18.389
0.461 0.192 5.778 0.016 1.586 1.089 2.309
140 Psychiatry Investig 2012;9:134-142
Dementia among Poor MMSE-KC Performance
Our study did not separate AD and dementia, so our result is
partially consistent with that of Gao et al.32
Recently, there has been conflicting evidence regarding gen-
der differences in dementia risk. In a recent metaanalysis, gen-
der was independently associated with dementia risk in all re-
gions other than North America and Pacific Asia.33 In the pre-
sent study, gender was not a correlate of dementia in univariate
or multivariate analysis. According to Kim et al.,9 gender dif-
ferences in mental health are often attributed to gender-related
differences in social exposure.34 Over the past few decades, how-
ever, rapid social and economic changes, such as the expansion
of formal education and of women’s participation in the labor
force, have had profound implications for Korean women.35 This
may have also contributed to our results.
Multivariate analyses showed that education was strongly as-
sociated with dementia. Lower education level is a well-known
risk factor for dementia, and our result supports previous find-
ings in this regard.30,36-38 The subjects of our research were at
risk for cognitive decline, and even among this population, ed-
ucation was, irrespective of gender, powerfully correlated with
dementia. This result suggests that, even in the case of groups
at risk for cognitive decline, lower education level could be re-
lated to the development of dementia. This is also partially in
accord with previous research39 suggesting that highly educated
individuals show fewer clinical symptoms of dementia than do
less educated individuals,40,41 and other research has suggested
that highly educated persons, who have greater cognitive reserve,
may demonstrate more efficient or flexible use of brain net-
works and cognitive paradigms.42 Intellectually challenging ac-
tivities, such as those involved in education and other complex
mental activities, are recognized as playing a significant role in
maintaining or enhancing brain reserve and thus providing pro-
tection against the risk of dementia in old age.36
Depression was not significantly associated with dementia in
the univariate analysis, but after controlling for multiple con-
founding factors, depression was found to be independently
correlated with dementia. This result is consistent with previ-
ous cross-sectional43-45 and longitudinal studies46-48 and meta-
analyses49 suggesting that depressive symptoms are common
in older persons and are associated with cognitive impairment
and dementia, especially AD, among the general population.
In fact, the relationship between depression and dementia
is much more complex. Researchers have suggested two possi-
bilities: depressive symptomatology may be a risk factor for de-
mentia or, as several investigators have hypothesized,47,48,50
depression may be an early sign of the disease rather than an
independent risk factor.
Recently, a co-twin control analysis found that the increased
likelihood of dementia associated with depression may not
be attributable to shared genes or shared early life influences,
showing that a twin who had a history of depression was three
times more likely to have dementia compared to his or her co-
twin. Wilson et al.46 suggested that the association of depres-
sive symptoms with clinical AD appears to be independent of
cortical plaques and tangles. Other researchers have highlight-
ed the effects of depression on hippocampal formation or on
the hypothalamo-pituitary-adrenal axis.51
We were unable to determine causality due to the cross-sec-
tional design of our study, but our results indicate that the pres-
ence of depression in a high-risk group may further influence
the development of dementia.
In Korea, nursing homes are usually for persons who are in
cognitive decline and who have no support system. Our results
showed that living in a nursing home was the strongest predic-
tor of dementia. This strong association may be due to the char-
acteristics of the 194 nursing home residents in our study, who
had MMSE-KC scores below -1.5 SD relative to the norm, and
46.1% of whom had already been diagnosed with dementia.
In contrast to previous studies,52-56 a history of head trauma
was not associated with dementia in the present study. The
univariate analysis showed an association, but the multivariate
analysis did not. Previous studies suggested that this associa-
tion could be due to increases in Aβ pathology57 and tau pa-
thology in brain tissue. Cerebrospinal fluid Aβ levels are ele-
vated, and APP is overproduced after brain injury.58 On the other
hand, this association may be attributable to selective recall
bias, as many prospective studies have failed to find a signifi-
cant association between dementia and head trauma.59 Our sam-
ple included only five persons with head trauma history, and
thus selection bias could also have led to our negative result.
Whether marital status is a correlate of dementia remains
controversial, but non-married status (including widowed/wid-
ower/unmarried) has been accepted as a risk factor for devel-
oping dementia in some studies. Our analysis did not show mar-
ital status to be a significant risk factor, a finding that is con-
sistent with a previous Korean study.9 Some, but not many, stu-
dies among Asians have found that widowed/unmarried in-
dividuals are at risk for dementia, and this may reflect a better
social support system among married subjects. However, this
correlation has not been found in other studies, and the asso-
ciation requires further clarification.18,60
The question of whether living in a rural area is correlated
with dementia is also controversial at this time. Although our
results showed that living arrangement was correlated with de-
mentia, the association was not quite significant (p=0.061). This
finding corresponds to findings from a previous Korean study9
and a Western study,18 but is not consistent with another study.61
This inconsistency among studies could be explained by group
and racial differences and, especially, by characteristics of Jeju
Island’s population, which cannot be easily differentiated into
MD Kim et al.
urban and rural areas in many respects. For example, the main
economic activity is centered in urban areas but also includes
farming activities that could be classified as rural. However, the
fact that all of our subjects had low MMSE-KC scores could re-
duce the impact of rural living on the risk of dementia.
Economic status is a well-known risk factor for dementia,31
and the usual explanation is that poor economic status is like-
ly related to lower education level. However, our results did not
reveal the same associations. This is likely due to the homoge-
nous characteristics of our group, that is, the NEDDP included
only persons of low socioeconomic status.
Multivariate analysis found that the number of medical ill-
ness was not a correlate of dementia in our study. Generally,
higher medical comorbidity is significantly associated with
lower cognitive functioning on the MMSE, taking into account
age, gender, education, and care setting.62 Higher medical co-
morbidity is also significantly associated with poorer self-care,
decreased mobility, and greater incontinence, adjusted for the
same demographic factors and for cognitive functioning. Thus,
medical comorbidities are implicated in cognitive decline, and
they may also adversely affect function and independence in-
dependent of cognitive status. The discrepancy between previ-
ous studies and our results could be explained by group differ-
ences. That is, our subjects were already characterized by cognitive
decline, poor socioeconomic status, and poor social support.
This study has some limitations. First, non-responders may
have had poorer health status than responders, which may have
resulted in an underestimation of the prevalence of dementia.
Second, the failure to consider certain known dementia risk fac-
tors, such as the apolipoprotein E genotype, smoking, obesity,
diabetes, vascular factors, and behavioral symptoms, means that
many confounding factors were not considered. Third, since all
participants of this research were recipients of financial supports,
it is hard to apply to the general population. Fourth, this study
was also limited by its cross-sectional nature which made it im-
possible to determine causal relationships between correlates
Despite some limitations, this study has several strengths. This
is the first study of this specific population, including a sizeable
sample over the age of 85 as well as long-term care residents. In
addition, we were able to minimize diagnostic variability, as all
research geropsychiatrists were certified for CERAD-K assess-
ment through formal training programs provided by the
In conclusion, the prevalence of dementia was very high
among older people with low MMSE-KC scores, and older age,
no education, nursing home residence, and depression were sig-
nificant correlates. Enhancing lifetime education by provid-
ing intellectually challenging activities as a means to improve
cognitive reserve, encouraging living at home rather than in a
nursing home, and preventing and treating depression in the
early phase could reduce dementia prevalence in this group.
This work was supported by the research grant from the Hyocheon Aca-
demic Research Fund of the Cheju National University in 2009.
1. Korea Statistics Office: Internal migration statistics 2005. Available at:
v=y. Accessed May 14, 2009.
2. Korea Statistics Office: Population projections for Korea 2005. Avail-
able at: http://meta.nso.go.kr/metaSearch/metasearch1.jsp?josa_
id=39&juki_id=5644. Accessed May 14, 2009.
3. OECD (Organisation for Economic Co-operation and Development).
Economic Survey of Korea 2005. Paris: OECD; 2005.
4. Statistics Korea. Report on the Population and Housing Census. Dae-
jeon: Statistics Korea; 2005, p. 7-53.
5. United Nations. World Population Prospects 2006. Available at: http://
Accessed June 30, 2007.
6. Suh GH. Dementia in Korea: trend and projection. J Korean Geriatr
7. Ernst RL, Hay JW. The US economic and social costs of Alzheimer’s
disease revisited. Am J Public Health 1994;84:1261-1264.
8. Kang IO, Park JY, Lee YK, Suh SR, Kim KH, Choi SJ. Analysis of So-
cioeconomic Costs for Dementia Patients Using Dementia Claim Da-
tabase of KNHI and NMA. Seoul: National Health Insurance Corpo-
9. Kim KW, Park JH, Kim MH, Kim MD, Kim BJ, Kim SK, et al. A na-
tionwide survey on the prevalence of dementia and mild cognitive im-
pairment in South Korea. J Alzheimers Dis 2011;23:281-291.
10. Alzheimer’s Association. 2010 Alzheimer’s disease facts and figures.
Alzheimers Dement 2010;6:158-194.
11. World Bank. 2006 World Development Indicators (WDI). Washington,
D.C: World Bank Publications, 2007, p. 20-23.
12. Sorensen S, Duberstein P, Gill D, Pinquart M. Dementia care: mental
health effects, intervention strategies, and clinical implications. Lancet
13. Kim MD, Hong SC, Lee CI, Kim SY, Kang IO, Lee SY. Caregiver bur-
den among caregivers of Koreans with dementia. Gerontology 2009;55:
14. Lee JH, Lee KU, Lee DY, Kim KW, Jhoo JH, Kim JH, et al. Develop-
ment of the Korean version of the Consortium to Establish a Registry
for Alzheimer’s Disease Assessment Packet (CERAD-K): clinical and
neuropsychological assessment batteries. J Gerontol B Psychol Sci Soc
15. Lee DY, Lee KU, Lee JH, Kim KW, Jhoo JH, Kim SY, et al. A normative
study of the CERAD neuropsychological assessment battery in the
Korean elderly. J Int Neuropsychol Soc 2004;10:72-81.
16. American Psychiatric Association. Diagnostic Criteria from DSM-IV.
Washington, D.C.: American Psychiatric Association; 1994.
17. Bae JN, Cho MJ. Development of the Korean version of the Geriatric
Depression Scale and its short form among elderly psychiatric patients.
J Psychosom Res 2004;57:297-305.
18. Hamid TA, Krishnaswamy S, Abdullah SS, Momtaz YA. Sociodemo-
graphic risk factors and correlates of dementia in older Malaysians.
Dement Geriatr Cogn Disord 2010;30:533-539.
19. Wimo A, Winblad B, Aguero-Torres H, von Strauss E. The magnitude
of dementia occurrence in the world. Alzheimer Dis Assoc Disord 2003;
20. Lee DY, Lee JH, Ju YS, Lee KU, Kim KW, Jhoo JH, et al. The prevalence
of dementia in older people in an urban population of Korea: the Seoul
142 Psychiatry Investig 2012;9:134-142
Dementia among Poor MMSE-KC Performance
study. J Am Geriatr Soc 2002;50:1233-1239.
21. Richards SS SR. Family History of AD. In: Sadock BJ, Sadock VA, Ruiz
P, Editors. Comprehensive Textbook of Psychiatry, 9th Edition. Phila-
delphia: Lippincot Williams & Wilkins, 2009, p. 1167-1168.
22. Gussekloo J, Heeren TJ, Izaks GJ, Lighthart GJ, Rooijmans HG. A
community based study of the incidence of dementia in subjects aged
85 years and over. J Neurol Neurosurg Psychiatry 1995;59:507-510.
23. Kim JM, Stewart R, Prince M, Shin IS, Yoon JS. Diagnosing dementia
in a developing nation: an evaluation of the GMS-AGECAT algorithm
in an older Korean population. Int J Geriatr Psychiatry 2003;18:331-
24. Kua EH. Dementia in elderly Malays--preliminary findings of a com-
munity survey. Singapore Med J 1993;34:26-28.
25. Krishnaswamy S, Kadir K, Ali RA, Sidi H, Mathews S. Prevalence of
dementia among Malaysia in an urban settlement in Malaysia. Neurol
J Southeast Asia 1997;2:159-162.
26. Lobo A, Saz P, Marcos G, Día JL, De-la-Cámara C, Ventura T, et al.
The ZARADEMP Project on the incidence, prevalence and risk factors
of dementia (and depression) in the elderly community: II. Methods
and first results. Eur J Psychiatry 2005;19:40-54.
27. Whalley LJ, Dick FD, McNeill G. A life-course approach to the aetiol-
ogy of late-onset dementias. Lancet Neurol 2006;5:87-96.
28. Ngandu T, von Strauss E, Helkala EL, Winblad B, Nissinen A, Tu-
omilehto J, et al. Education and dementia: what lies behind the associ-
ation? Neurology 2007;69:1442-1450.
29. Goodman Y, Bruce AJ, Cheng B, Mattson MP. Estrogens attenuate and
corticosterone exacerbates excitotoxicity, oxidative injury, and amyloid
beta-peptide toxicity in hippocampal neurons. J Neurochem 1996;66:
30. Launer LJ, Andersen K, Dewey ME, Letenneur L, Ott A, Amaducci
LA, et al. Rates and risk factors for dementia and Alzheimer’s disease:
results from EURODEM pooled analyses. EURODEM Incidence Re-
search Group and Work Groups. European Studies of Dementia. Neu-
31. De Deyn PP, Goeman J, Vervaet A, Dourcy-Belle-Rose B, Van Dam D,
Geerts E. Prevalence and incidence of dementia among 75-80-year-old
community-dwelling elderly in different districts of Antwerp, Belgium:
the Antwerp Cognition (ANCOG) Study. Clin Neurol Neurosurg 2011;
32. Gao S, Hendrie HC, Hall KS, Hui S. The relationships between age,
sex, and the incidence of dementia and Alzheimer disease: a meta-
analysis. Arch Gen Psychiatry 1998;55:809-815.
33. ADI.Global Prevalence of Dementia. In: Martin P JJ, Editor. Alzheim-
er’s Disease International, 2009, p. 25-46.
34. Jeon GS, Jang SN, Rhee SJ, Kawachi I, Cho SI. Gender differences in
correlates of mental health among elderly Koreans. J Gerontol B Psy-
chol Sci Soc Sci 2007;62:S323-S329.
35. Palley ML. Women’s status in South Korea: tradition and change.
Asian Survey 1990;30:1136-1153.
36. Valenzuela MJ, Sachdev P. Brain reserve and dementia: a systematic
review. Psychol Med 2006;36:441-454.
37. Mortimer JA, Snowdon DA, Markesbery WR. Head circumference,
education and risk of dementia: findings from the Nun Study. J Clin
Exp Neuropsychol 2003;25:671-679.
38. Letenneur L, Launer LJ, Andersen K, Dewey ME, Ott A, Copeland JR,
et al. Education and the risk for Alzheimer’s disease: sex makes a dif-
ference. EURODEM pooled analyses. EURODEM Incidence Research
Group. Am J Epidemiol 2000;151:1064-1071.
39. Roe CM, Xiong C, Miller JP, Morris JC. Education and Alzheimer dis-
ease without dementia: support for the cognitive reserve hypothesis.
40. Stern Y, Tang MX, Denaro J, Mayeux R. Increased risk of mortality in
Alzheimer’s disease patients with more advanced educational and oc-
cupational attainment. Ann Neurol 1995;37:590-595.
41. Stern Y. What is cognitive reserve? Theory and research application of
the reserve concept. J Int Neuropsychol Soc 2002;8:448-460.
42. Stern Y. The concept of cognitive reserve: a catalyst for research. J Clin
Exp Neuropsychol 2003;25:589-593.
43. Burt DB, Zembar MJ, Niederehe G. Depression and memory impair-
ment: a meta-analysis of the association, its pattern, and specificity.
Psychol Bull 1995;117:285-305.
44. Rabbitt P, Donlan C, Watson P, McInnes L, Bent N. Unique and inter-
active effects of depression, age, socioeconomic advantage, and gender
on cognitive performance of normal healthy older people. Psychol Ag-
45. Teri L, Wagner A. Alzheimer’s disease and depression. J Consult Clin
46. Wilson RS, Barnes LL, Mendes de Leon CF, Aggarwal NT, Schneider
JS, Bach J, et al. Depressive symptoms, cognitive decline, and risk of
AD in older persons. Neurology 2002;59:364-370.
47. Berger AK, Fratiglioni L, Forsell Y, Winblad B, Backman L. The occur-
rence of depressive symptoms in the preclinical phase of AD: a popu-
lation-based study. Neurology 1999;53:1998-2002.
48. Devanand DP, Sano M, Tang MX, Taylor S, Gurland BJ, Wilder D, et
al. Depressed mood and the incidence of Alzheimer’s disease in the el-
derly living in the community. Arch Gen Psychiatry 1996;53:175-182.
49. Jorm AF. History of depression as a risk factor for dementia: an updat-
ed review. Aust N Z J Psychiatry 2001;35:776-781.
50. Chen P, Ganguli M, Mulsant BH, DeKosky ST. The temporal relation-
ship between depressive symptoms and dementia: a community-based
prospective study. Arch Gen Psychiatry 1999;56:261-266.
51. Reitz C, Brayne C, Mayeux R. Epidemiology of Alzheimer disease. Nat
Rev Neurol 2011;7:137-152.
52. Mayeux R, Ottman R, Maestre G, Ngai C, Tang MX, Ginsberg H, et al.
Synergistic effects of traumatic head injury and apolipoprotein-epsilon
4 in patients with Alzheimer’s disease. Neurology 1995;45:555-557.
53. Rasmusson D, Brandt J, Martin D, Folstein M. Head injury as a risk
factor in Alzheimer’s disease. Brain Inj 1995;9:213-219.
54. Schofield PW, Tang M, Marder K, Bell K, Dooneief G, Chun M, et al.
Alzheimer’s disease after remote head injury: an incidence study. J
Neurol Neurosurg Psychiatry 1997;62:119-124.
55. Fleminger S, Oliver DL, Lovestone S, Rabe-Hesketh S, Giora A. Head
injury as a risk factor for Alzheimer’s disease: the evidence 10 years on;
a partial replication. J Neurol Neurosurg Psychiatry 2003;74:857-862.
56. Mortimer JA, van Duijn CM, Chandra V, Fratiglioni L, Graves AB,
Heyman A, et al. Head trauma as a risk factor for Alzheimer’s disease:
a collaborative re-analysis of case-control studies. EURODEM Risk
Factors Research Group. Int J Epidemiol 1991;20(Suppl 2):S28-S35.
57. Hartman RE, Laurer H, Longhi L, Bales KR, Paul SM, McIntosh TK,
et al. Apolipoprotein E4 influences amyloid deposition but not cell loss
after traumatic brain injury in a mouse model of Alzheimer’s disease. J
58. Franz G, Beer R, Kampfl A, Engelhardt K, Schmutzhard E, Ulmer H,
et al. Amyloid beta 1-42 and tau in cerebrospinal fluid after severe
traumatic brain injury. Neurology 2003;60:1457-1461.
59. Youn JC, Lee DY, Kim KW, Woo JI. Epidemiology of dementia. Psy-
chiatry Invest 2005;2:28-39.
60. Poddar K, Kant S, Singh A, Singh TB. An epidemiological study of de-
mentia among the habitants of eastern Uttar Pradesh, India. Ann Indi-
an Acad Neurol 2011;14:164-168.
61. Gureje O, Ogunniyi A, Kola L, Abiona T. Incidence of and risk factors
for dementia in the Ibadan study of aging. J Am Geriatr Soc 2011;59:
62. Doraiswamy PM, Leon J, Cummings JL, Marin D, Neumann PJ. Prev-
alence and impact of medical comorbidity in Alzheimer’s disease. J
Gerontol A Biol Sci Med Sci 2002;57:M173-M177.