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American Journal of Alzheimer's Disease and Other Dementias logoLink to American Journal of Alzheimer's Disease and Other Dementias
. 2016 Jul 9;31(6):481–491. doi: 10.1177/1533317515628048

Depression in the Family of Patients With Dementia in Korea

Sung-In Jang 1, Hong-Chul Bae 1, Jaeyong Shin 1, Suk-yong Jang 1, Seri Hong 1,2, Kyu-Tae Han 1, Eun-Cheol Park 1,✉
PMCID: PMC10852979  PMID: 26888863

Abstract

Introduction:

Dementia is the leading cause of disability worldwide in the elderly individuals. Although prior studies have examined psychiatric symptoms in dementia caregivers, few studies have examined physician-diagnosed depression in the family caregiver of a patient with dementia.

Methods:

We used data from 457 864 respondents from the Korea Community Health Survey. We used logistic regression to examine the relationship between physician-diagnosed depression and cohabitation with a patient with dementia.

Results:

Cohabitation with a patient with dementia (1.2% of the Korean population) was significantly associated with physician-diagnosed depression. The significance remained in females when the data were stratified by sex. A significant association also occurred among males with low family income.

Conclusion:

To reduce the burden of dementia, we need a management policy that includes the caregiver as well as the patient with dementia. In particular, political management for the vulnerable population, male caregiver in low-income family and female caregiver in high-income family, should be prepared.

Keywords: dementia, caregiver, depression, community health survey

Introduction

Dementia is the leading cause of disability among the elderly individuals and is a major contributor to mortality as well as a challenge to the health care system worldwide. 1 In 2010, an estimated 35.6 million people were living with dementia worldwide, and these numbers are expected to double approximately every 20 years to 65.7 million in 2030 and 115.4 million in 2050. 2

Dementia is an umbrella term to describe a variety of diseases and conditions that develop when nerve cells in the brain die or no longer function normally. 3 Dementia includes Alzheimer’s disease (AD), vascular dementia (VD), dementia with Lewy bodies, frontotemporal lobar degeneration, and Parkinson’s disease. The early signs of AD, which is the most common type of dementia, include sporadic memory loss and subtle behavioral changes. Alzheimer’s disease gradually progresses until, often after a decade or more, the individual is unable to speak or comprehend language, can no longer control his or her bowels, and requires assistance with all aspects of personal care. 4

No cure for dementia currently exists, and the number of individuals with AD and other types of dementia continues to grow. 5 The home-based care of individuals with dementia is an important topic to address. The burden on caregivers is known to be higher among those who care for a patient with dementia compared to those who care for patients with other medical illnesses. 6 Home-based caregivers play an important role in the management of dementia, and several studies have demonstrated that this role has a strong impact on the physical and mental health of the caregiver. In particular, caregivers of patients with dementia have poor sleep, exhaustion, and depression. 7,8 Given the impending worldwide dementia epidemic, caregiver burden has become one of the main concerns in the dementia clinic as well as for researchers and health care policy makers. 9

Meanwhile, depression is one of the most prevalent issues globally. 10 According to Blazer, 11 Pinquart et al, 12 and Wilkins et al, 13 depression is associated with a significant increased risk of functional decline and all-cause mortality in older adults. Poor health and impaired functioning are also found to be associated with depressive symptoms, so depression places a considerable burden on both society and individual. 14

Depression of family caregivers of people with dementia is well known in Western countries. 15 An obvious association between dementia caregiving and negative effects on psychological health has been demonstrated in numerous studies. 16,17

In Korea, the prevalence of dementia has increased sharply as the overall population ages. Previous studies have reported that the prevalence of dementia is between 7.2% and 8.1% among the urban Korean elderly population. 18,19 In addition, the prevalence of AD and VD has been estimated to range from 4.2% to 6.5% and 1.3% to 2.5%, respectively, in the Korean population. 20 –22 Many studies have examined the health of the caregivers of patients with dementia in Korea. For example, Han et al 9 have analyzed the association between the burden on the caregivers of patients with dementia and the caregiver’s social supports, and both Kang et al 23 and Lim et al 24 have reported on the factors that contribute to the burden on the caregivers of patients with dementia. Shin et al 25 compared the caregiver burden between those who cared for patients with Parkinson’s disease and dementia and those who had patients with AD, and Lee et al 26 studied stress among caregivers of patients with dementia in Korea. These studies, however, are limited by small sample sizes and do not represent the entire Korean population. The purpose of this study, therefore, was to analyze the association between physician-diagnosed depression and cohabitation with a patient with dementia using national representative data. A secondary purpose of this study was to examine this association stratified by sex and economic status.

Methods

Dataset

The data used in this study came from the Korea Community Health Survey (KCHS), which was administered by the Korean Centers for Disease Control and Prevention in 2011 and 2012. The KCHS standardized questionnaire was developed jointly by the Korea Centers for Disease Control and Prevention staff, a working group of health indicators standardization subcommittee, and 16 metropolitan cities and provinces with 253 regional sites. The questionnaire covers a variety of topics related to health behaviors and prevention, which is used to assess the prevalence of personal health practices and behaviors related to the leading causes of disease, including smoking, alcohol use, drinking and driving, high-blood pressure control, physical activity, weight control, quality of life (European Quality of Life-5 Dimensions, European Quality of Life-Visual Analogue Scale, Korean Instrumental Activities of Daily Living), medical service, accident, injury, and so on. The microdata (in the form of Statistical Analysis Software [SAS] files) and analytic guidelines can be downloaded from the KCHS website (http://KCHS.cdc.go.kr/) in Korean. 27

Participant

Data were gathered for 458 147 individuals (229 226 in 2011 and 228 921 in 2012). Data from both years were integrated and sampling weights were incorporated for the analysis. The final analysis used data from 457 864 individuals after excluding 283 people for whom information on physician-diagnosed depression and/or cohabitation with a patient with dementia was unavailable (209 were missing information about depression, 77 were missing information about cohabitation with a patient with dementia, and 3 were missing both). Our study did not need to address any ethical concerns because the Community Health Survey data are secondary data that are available in the public domain and do not contain private information.

Table 1 presents the demographic information from the 457 864 participants who were included in the analysis stratified by sex. The proportion of individuals who reported cohabitation with a patient with dementia was 1.2% across both sexes. The average age of males surveyed was 51.2 years, which was 1.5 years older on average than female respondents. The dominant employment type was site worker (44.4%) among male respondents and unemployed/homemaker (49.1%) among female respondents. The majority (38.5%) of males reported their highest level of education as university graduate or higher. In contrast, the majority of female respondents had a low education level (elementary school: 34.4%). The proportion of respondents with physician-diagnosed depression was 1.2% among males and 3.6% among females. The overall prevalence of depression across all survey respondents was 2.5%.

Table 1.

Study Population Characteristics.

(n, %)
Total Male Female P Value
Cohabitation with a patient with dementia Yes 5360 1.2 2398 1.2 2962 1.2 .752
No 452 504 98.8 203 421 98.8 249 083 98.8
Age Mean, SD 51.2 16.9 50.4 16.3 51.9 17.3 <.001
Employment status Office worker 142 517 31.2 68 604 33.4 73,913 29.4
Site worker 145 625 31.8 91 276 44.4 54,349 21.6
Unemployed/homemaker 169 190 37.0 45 642 22.2 123 548 49.1
Highest level of education Elementary school 121 878 26.7 35 365 17.2 86 513 34.4 <.001
Middle school 53 307 11.7 25 185 12.3 28 122 11.2
High school 133 453 29.2 65 815 32.0 67 638 26.9
University or higher 148 334 32.5 79 066 38.5 69 268 27.5
Marital status Single 66 204 14.5 36 550 17.8 29 654 11.8 <.001
Living with spouse 315 579 69.0 152 992 74.4 162 587 64.6
Separated/divorced/widowed 75 746 16.6 16 134 7.8 59 612 23.7
Family income level First quartile (highest) 112 621 26.4 54 115 28.2 58 506 25.0 <.001
Second quartile 96 212 22.6 45 313 23.6 50,899 21.7
Third quartile 107 002 25.1 48 525 25.2 58 477 25.0
Fourth quartile (lowest) 110 734 26.0 44 264 23.0 66 470 28.4
Number of family members 1 47 860 10.5 14 519 7.1 33 341 13.2 <.001
2 145 088 31.7 69 005 33.5 76 083 30.2
3 96 092 21.0 45 498 22.1 50 594 20.1
4 112 384 24.6 52 541 25.5 59 843 23.7
5+ 56 440 12.3 24 256 11.8 32 184 12.8
Insurance type Medical aid 15 768 3.4 5877 2.9 9891 3.9 <.001
National Health Insurance 441 973 96.6 199 892 97.1 242 081 96.1
Self-reported health condition Excellent 180 117 39.3 93 099 45.2 87 018 34.5 <.001
Average 179 979 39.3 78 140 38.0 101 839 40.4
Poor 97 706 21.3 34 550 16.8 63 156 25.1
Self-reported stress Very often 15 216 3.3 6662 3.2 8554 3.4 <.001
Often 105 871 23.2 45 920 22.3 59 951 23.8
Occasionally 243 744 53.3 109 361 53.2 134 383 53.4
Seldom 92 483 20.2 43 719 21.3 48 764 19.4
Smoking habit Never 287 942 62.9 49 530 24.1 238 412 94.6 <.001
Past 73 395 16.0 67 811 33.0 5584 2.2
Current 96 452 21.1 88 442 43.0 8010 3.2
Alcohol use No 156 969 34.3 44 404 21.6 112 565 44.7 <.001
Yes 300 844 65.7 161 401 78.4 139 443 55.3
Hours of sleep per night Less than 6 hours 71 318 15.6 28 597 13.9 42 721 17.0 <.001
6 hours 130 080 28.4 61 957 30.1 68 123 27.1
7 hours 145 982 31.9 67 205 32.7 78 777 31.3
8 hours 90 408 19.8 39 516 19.2 50 892 20.2
More than 9 hours 19 624 4.3 8407 4.1 11 217 4.5
Underlying chronic diseasea Yes 167 733 36.6 68 578 33.3 99 155 39.3 <.001
No 290 131 63.4 137 241 66.7 152 890 60.7
Physician-diagnosed depression Yes 11 422 2.5 2424 1.2 8998 3.6 <.001
No 446 442 97.5 203 395 98.8 243 047 96.4
Survey year 2011 229 059 50.0 102 958 50.0 126 101 50.0 .959
2012 228 805 50.0 102 861 50.0 125 944 50.0
Total 457 864 100 205 819 45.0 252 045 55.0
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aUnderlying chronic disease includes hypertension, diabetes, dyslipidemia, and arthritis.

Interesting Variable

The variable of interest in this study was the existence of a cohabitating patient with dementia in the family. We defined the family caregiver of a patient with dementia as any individual who resided with a patient having dementia, a definition that is consistent with a previous study. 28 The Community Health Survey asked each individual “Do you live with a dementia patient in your family?” and the response choices were binary (yes or no). The dependent variable in this study was the existence of physician-diagnosed depression in the respondent. The Community Health Survey asked “Have you ever been diagnosed with depression by a doctor?” and the response choices were binary (yes or no).

Independent Variables

The independent variables included the survey year, sex, age, employment status, education level, marital status, family income, number of family members, insurance type, self-reported health condition, self-reported stress, smoking habit, alcohol use, number of hours of sleep per night, and the existence of an underlying chronic disease in the respondent. Age was analyzed as a continuous variable. The employment variable was divided into 3 categories: office worker, site worker, and unemployed/homemaker. The education-level variable was divided into 4 categories: graduation from university or higher, graduation from high school, graduation from middle school, and graduation from elementary school. The marital status variable was divided into 3 categories: single, married living with spouse, and separated/divorced/widowed. We used square root scale for family income, which divides household income by the square root of household size. 29 The family income variable was divided into 4 quartiles adjusted by family size. The number of family members variable was divided into 5 groups: 1,2,3,4 and 5+. The medical insurance-type variable was divided into 2 categories: National Health Insurance (NHI) and Medical aid. Universal coverage with NHI for Koreans was achieved in 1989, and Medical aid contributes to the social welfare and health of citizens with a low economic status, and it helps them receive medical services at minimal or no cost. In 2010, 96.4% of all citizens were covered by NHI and 3.6% by Medical aid. 30 The Medical aid program classifies beneficiaries into 2 categories, type 1 and 2, on the basis of being incapable (those younger that 18 or older than 65 years of age, or disabled) or capable of working, respectively. 31 The self-reported health condition variable was divided into 3 categories: excellent, average, and poor. The self-reported stress variable was divided into 4 categories: very often, often, occasionally, and seldom. The smoking habit variable was divided into 3 categories: never, past, and current smoker. The alcohol use variable was divided into 2 categories: no and yes. Because sleep duration is independently associated with depression, we divided this variable into 5 categories by the number of hours of sleep per night: less than 6 hours, 6 hours, 7 hours, 8 hours, and more than 9 hours. 32 The variable about the existence of an underlying disease considered individuals who were diagnosed with hypertension, diabetes, dyslipidemia, or any type of arthritis by a doctor. The survey year variable was divided into 2 categories: 2011 and 2012. All variables had statistically significant associations with physician-diagnosed depression except the survey year variable.

Statistical Analysis

The data analysis was conducted using the χ2 test and logistic regression in SAS 9.4 (SAS Institute, Inc.; Cary, North Carolina). The data were analyzed over the entire population and then stratified by sex and family income level. Results with a P value <.05 were considered significant.

Results

Table 2 presents the results of the univariate analyses that examined the association between physician-diagnosed depression and each variable by sex. The results of the chi-square test revealed that cohabitation with a patient with dementia was significantly associated with physician-diagnosed depression. The percentage of respondents with physician-diagnosed depression among those who lived with a patient with dementia was twice that of those who did not live with a patient with dementia (5.0% vs 2.5%, respectively). The average age of the respondents with physician-diagnosed depression (56.0 years) was higher than that of nondepressed respondents. In addition, the prevalence of physician-diagnosed depression was twice as high in respondents who identified their employment status as unemployed/homemaker as those who identified their employment status as an office worker (1.4%) or a site worker (1.9%). The prevalence of depression was higher in the lower income groups (4th quartile: 4.1%) and 3 times as high in respondents with Medical aid compared with NHI (7.7% vs 2.3%, respectively). Physician-diagnosed depression was also higher among those respondents who reported poor health (6.5%) and more stress (10.8%). In addition, physician-diagnosed depression was higher among respondents who reported too little sleep (<6 hours, 4.7%) as well as too much sleep (>9 hours, 4.5%). Respondents who reported an underlying chronic disease had a 4.0% prevalence of physician-diagnosed depression.

Table 2.

Associations Between Physician-Diagnosed Depression and Subject Demographics.

(n, %)
Both Sexes Male Female
Diagnosed depression Nondiagnosed P Value Diagnosed Depression Nondiagnosed P Value Diagnosed Depression Nondiagnosed P Value
Cohabitation with a patient with dementia Yes 267 5.0 5093 95.0 <.001 66 2.8 2332 97.3 <.001 201 6.8 2761 93.2 <.001
No 11 155 2.5 441 349 97.5 2358 1.2 201 063 98.8 8797 3.5 240 286 96.5
Age Mean, SD 56 15.3 51.1 16.9 <.001 54.9 16.8 50.4 16.3 <.001 56.3 14.8 51.7 17.3 <.001
Employment status Office worker 1987 1.4 140 530 98.6 <.001 435 0.6 68 169 99.4 <.001 1552 2.1 72 361 97.9 <.001
Site worker 2694 1.9 142 931 98.2 783 0.9 90 493 99.1 1911 3.5 52 438 96.5
Unemployed or homemaker 6732 4.0 162 458 96.0 1204 2.6 44 438 97.4 5528 4.5 118 020 95.5
Highest level of education Elementary school 4612 3.8 117 266 96.2 <.001 578 1.6 34 787 98.4 <.001 4034 4.7 82 479 95.3 <.001
Middle school 1897 3.6 51 410 96.4 416 1.7 24 769 98.4 1481 5.3 26 641 94.7
High school 2973 2.2 130 480 97.8 736 1.1 65 079 98.9 2237 3.3 65 401 96.7
University or higher 1915 1.3 146 419 98.7 694 0.9 78 372 99.1 1221 1.8 68 047 98.2
Marital status Single 1091 1.7 65 113 98.4 <.001 536 1.5 36 014 98.5 <.001 555 1.9 29 099 98.1 <.001
Living with spouse 7016 2.2 308 563 97.8 1461 1.0 151 531 99.1 5555 3.4 157 032 96.6
Separated/divorced/widowed 3305 4.4 72 441 95.6 426 2.6 15 708 97.4 2879 4.8 56 733 95.2
Family income level 1st quartile (highest) 1809 1.6 110 812 98.4 <.001 377 0.7 53 738 99.3 <.001 1432 2.5 57 074 97.6 <.001
2nd quartile 1617 1.7 94 595 98.3 327 0.7 44 986 99.3 1290 2.5 49 609 97.5
3rd quartile 2688 2.5 104 314 97.5 564 1.2 47 961 98.8 2124 3.6 56 353 96.4
4th quartile (lowest) 4573 4.1 106 161 95.9 997 2.3 43 267 97.8 3576 5.4 62 894 74.6
Number of family members 1 1923 4.0 45 937 96.0 <.001 339 2.3 14 180 97.7 <.001 1584 4.8 31 757 95.3 <.001
2 4372 3.0 140 716 97.0 1006 1.5 67 999 98.5 3366 4.4 72 717 95.6
3 2174 2.3 93 918 97.7 493 1.1 45 005 98.9 1681 3.3 48 913 96.7
4 1793 1.6 110 591 98.4 368 0.7 52 173 99.3 1425 2.4 58 418 97.6
5+ 1160 2.1 55 280 97.9 218 0.9 24 038 99.1 942 2.9 31 242 97.1
Insurance type Medical aid 1212 7.7 14 556 92.3 <.001 330 5.6 5547 94.4 <.001 882 8.9 9009 91.1 <.001
National Health Insurance 10 206 2.3 431 767 97.7 2094 1.1 197 798 99.0 8112 3.4 233 969 96.7
Self-reported health condition Excellent 1473 0.8 178 644 99.2 <.001 407 0.4 92 692 99.6 <.001 1066 1.2 85 952 98.8 <.001
Average 3642 2.0 176 337 98.0 736 0.9 77 404 99.1 2906 2.9 98 933 97.2
Poor 6305 6.5 91 401 93.6 1280 3.7 33 270 96.3 5025 8.0 58 131 92.0
Self-reported stress Very often 1647 10.8 13 569 89.2 <.001 391 5.9 6271 94.1 <.001 1256 14.7 7298 85.3 <.001
Often 5060 4.8 100 811 95.2 1014 2.2 44 906 97.8 4046 6.8 55 905 93.3
Occasionally 3582 1.5 240 162 98.5 764 0.7 108 597 99.3 2818 2.1 131 565 97.9
Seldom 1112 1.2 91 371 98.8 251 0.6 43 468 99.4 861 1.8 47 903 98.2
Smoking habit Never 8448 2.9 279 494 97.1 <.001 525 1.1 49 005 98.9 <.001 7923 3.3 230 489 96.7 <.001
Past 1278 1.7 72 117 98.3 909 1.3 66 902 98.7 369 6.6 5215 93.4
Current 1691 1.8 94 761 98.3 988 1.1 87 454 98.9 703 8.8 7307 91.2
Alcohol use No 5648 3.6 151 321 96.4 <.001 916 2.1 43 488 97.9 <.001 4732 4.2 107 833 95.8 <.001
Yes 5773 1.9 295 071 98.1 1507 0.9 159 894 99.1 4266 3.1 135 177 96.9
Hours of sleep per night Less than 6 hours 3320 4.7 67 998 95.3 <.001 574 2.0 28 023 98.0 <.001 2746 6.4 39 975 93.6 <.001
6 hours 2624 2.0 127 456 98.0 528 0.9 61 429 99.2 2096 3.1 66 027 96.9
7 hours 2506 1.7 143 476 98.3 545 0.8 66 660 99.2 1961 2.5 76 816 97.5
8 hours 2072 2.3 88 336 97.7 494 1.3 39 022 98.8 1578 3.1 49 314 96.9
More than 9 hours 875 4.5 18 749 95.5 279 3.3 8128 96.7 596 5.3 10 621 94.7
Underlying chronic diseasea Yes 6769 4.0 160 964 96.0 <.001 1270 1.9 67 308 98.2 <.001 5499 5.6 93 656 94.5 <.001
No 4653 1.6 285 478 98.4 1154 0.8 136 087 99.2 3499 2.3 149 371 97.7
Survey year 2011 5802 2.5 223 257 97.5 <.001 1218 1.2 101 740 98.8 .824 4584 3.6 121 517 96.4 .078
2012 5620 2.5 223 185 97.5 1206 1.2 101 655 98.8 4414 3.5 121 530 96.5
Sex Male 2424 1.2 203 395 98.8 .096
Female 8998 3.6 243 047 96.4
Total 11 422 2.5 446 442 97.5 2424 1.2 203 395 98.8 8998 3.6 243 047 96.4
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aUnderlying chronic disease includes hypertension, diabetes, dyslipidemia, and arthritis.

In the analysis stratified by sex, the prevalence of physician-diagnosed depression among male respondents who resided with a patient with dementia was 2.8%. Meanwhile, the prevalence of physician-diagnosed depression among female respondents who resided with a patient with dementia was 6.8%, which represented a prevalence approximately twice that of female respondents who did not reside with a patient with dementia (3.5%). The average age of physician-diagnosed males with depression was higher than nondepressed males (54.9 vs 54.0 years, respectively). The average age of female respondents who were diagnosed with depression was 56.3 years (nondepressed females 51.7). In both sexes, the percentage of people with physician-diagnosed depression, who reported their employment status as unemployed/homemaker was higher than for males in the other job groups (male: 2.6%; female: 2.3%). The highest prevalence of physician-diagnosed depression was also found among female respondents in the lowest income group (4.5%) and in those who reported living alone (4.8%) as well as those who reported a current smoking habit (8.8%) or slept less than 6 hours per night (6.4%).

Table 3 reports the logistic regression results for the association between physician-diagnosed depression and cohabitation with a patient with dementia for all variables. For both male and female respondents, those who resided with a patient with dementia had increased odds of physician-diagnosed depression compared to those who did not reside with a patient with dementia (odds ratio [OR] 1.33, 95% confidence interval [CI] 1.09-1.61, P value = .004). Based on these results, respondents who reported their employment status as office worker or site worker had significantly lower odds of physician-diagnosed depression than those who reported their employment status as unemployed/homemaker (office worker: OR 0.58, 95% CI 0.54-0.63, P value ≤ .001; site worker: OR 0.67, 95% CI 0.62-0.72, P value < .001). Similarly, respondents who reported their highest level of education as high school or middle school had significantly higher odds of diagnosed depression than those whose highest level of education was university graduate or higher (high school: OR 1.34, 95% CI 1.23-1.48, P value < .001; middle school: OR 1.53, 95% CI 1.36-1.72, P value < .001). Respondents who reported their family income level in the third or fourth quartile, which represented the lowest family income levels, had significantly higher odds of physician-diagnosed depression than those who reported their family income level in the first quartile (third quartile: OR 1.15, 95% CI 1.06-1.25, P value = .001; fourth quartile: OR 1.16, 95% CI 1.05-1.27, P value = .004). Respondents with Medical aid had significantly higher odds of physician-diagnosed depression (OR 1.45, 95% CI 1.31-1.61, P value < .001) than respondents with NHI. Respondents who were past or current smokers (past smoker: OR 1.43, 95% CI 1.28-1.60, P value < .001; current smoker: OR 1.33, 95% CI 1.20-1.49, P value < .001) also had significantly higher odds of physician-diagnosed depression than respondents who were nonsmokers.

Table 3.

Adjusted Odds Ratios and 95% CI for the Existence of Physician-Diagnosed Depression for Each Variable by Sex.

Both sexes, n = 457 864 Male, n = 205 819 Female, n = 252 045
OR 95% CI P Value OR 95% CI P Value OR 95% CI P Value
Cohabitation with a patient with dementia Yes 1.33 1.09-1.61 .004 1.26 0.87-1.82 .214 1.33 1.06-1.67 .013
No 1.00 1.00 1.00
Age Per 1 year older 0.99 0.99-0.99 <.001 1.00 1.00-1.01 .269 0.99 0.98-0.99 <.001
Employment status Office worker 0.58 0.54-0.63 <.001 0.56 0.46-0.67 <.001 0.63 0.58-0.69 <.001
Site worker 0.67 0.62-0.72 <.001 0.58 0.50-0.69 <.001 0.8 0.73-0.87 <.001
Unemployed or homemaker 1.00 1.00 1.00
Highest level of education Elementary school 0.98 0.86-1.11 .709 0.58 0.47-0.73 <.001 1.17 1.00-1.37 .05
Middle school 1.53 1.36-1.72 <.001 0.94 0.75-1.17 .568 1.74 1.52-2.00 <.001
High school 1.34 1.23-1.47 <.001 0.98 0.83-1.15 .796 1.44 1.29-1.60 <.001
University or higher 1.00 1.00 1.00
Marital status Single 1.00 1.00 1.00
Living with spouse 0.96 0.86-1.06 .398 0.47 0.38-0.58 <.001 1.45 1.26-1.67 <.001
Separated/divorced/widowed 1.13 1.00-1.28 .059 0.78 0.62-0.99 .038 1.6 1.36-1.88 <.001
Family income level 1st quartile (highest) 1.00 1.00 1.00
2nd quartile 0.99 0.91-1.09 .858 1.09 0.90-1.32 .369 0.96 0.86-1.06 .382
3rd quartile 1.15 1.06-1.25 .001 1.26 1.05-1.52 .012 1.09 0.99-1.20 .074
4th quartile (lowest) 1.16 1.05-1.27 .004 1.24 1.01-1.53 .045 1.09 0.98-1.22 .125
Number of family members 1 1.23 1.08-1.39 .001 1.20 0.91-1.57 .201 1.18 1.02-1.35 .022
2 1.23 1.11-1.36 <.001 1.27 1.01-1.59 .044 1.15 1.03-1.28 .016
3 1.07 0.96-1.19 .202 1.05 0.84-1.32 .672 1.03 0.92-1.15 .629
4 0.94 0.85-1.05 .278 0.87 0.69-1.10 .253 0.96 0.85-1.07 .452
5+ 1.00 1.00 1.00
Insurance type Medical aid 1.45 1.31-1.61 <.001 1.67 1.37-2.03 <.001 1.35 1.20-1.52 <.001
National Health Insurance 1.00 1.00 1.00
Self-reported health condition Excellent 1.00 1.00 1.00
Average 1.93 1.77-2.11 <.001 1.92 1.61-2.30 <.001 1.94 1.75-2.14 <.001
Poor 4.31 3.91-4.76 <.001 4.57 3.74-5.59 <.001 4.19 3.74-4.69 <.001
Self-reported stress Very often 6.86 6.07-7.75 <.001 7.7 6.01-9.87 <.001 6.63 5.77-7.62 <.001
Often 3.46 3.12-3.82 <.001 4.02 3.27-4.93 <.001 3.31 2.95-3.71 <.001
Occasionally 1.30 1.17-1.44 <.001 1.47 1.19-1.81 <.001 1.25 1.11-1.4 <.001
Seldom 1.00 1.00 1.00
Smoking habit Never 1.00 1.00 1.00
Past 1.43 1.28-1.60 <.001 1.21 1.02-1.43 .03 1.48 1.27-1.73 <.001
Current 1.33 1.20-1.49 <.001 1.00 0.85-1.17 .972 1.92 1.70-2.17 <.001
Alcohol use No 1.00 1.00 1.00
Yes 0.94 0.89-1.01 .078 0.75 0.65-0.87 <.001 1.01 0.95-1.09 .700
Hours of sleep per night Less than 6 hours 1.48 1.37-1.60 <.001 1.30 1.09-1.55 .003 1.54 1.41-1.68 <.001
6 hours 1.06 0.98-1.14 .182 0.94 0.79-1.11 .468 1.10 1.01-1.20 .037
7 hours 1.00 1.00 1.00
8 hours 1.22 1.12-1.33 <.001 1.26 1.05-1.51 .013 1.20 1.09-1.32 <.001
More than 9 hours 1.93 1.71-2.17 <.001 2.24 1.79-2.81 <.001 1.79 1.56-2.05 <.001
Underlying chronic diseasea Yes 1.53 1.43-1.65 <.001 1.50 1.30-1.74 <.001 1.56 1.44-1.70 <.001
No 1.00 1.00 1.00
Survey year 2011 1.02 0.96-1.08 .53 0.97 0.86-1.09 .578 1.04 0.97-1.10 .262
2012 1.00 1.00 1.00
Sex Male 0.34 0.31-0.38 <.001
Female 1.00
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Abbreviation: OR, odds ratio; CI, confidence interval.

aUnderlying chronic disease includes hypertension, diabetes, dyslipidemia, and arthritis.

When the data were stratified by sex, a significant association between physician-diagnosed depression and cohabitation with a patient with dementia remained among females (OR 1.33, 95% CI 1.06-1.67, P value = .013) but not for males (OR 1.26, 95% CI 0.87-1.82, P value = .214) . Based on the results for all adjusted variables, male respondents who reported elementary school as their highest level of education had significantly lower odds for diagnosed depression than males who graduated from university or higher (OR 0.58, 95% CI 0.47-0.73, P value < .001). Female respondents who reported high school or middle school as their highest level of education had significantly higher odds of physician-diagnosed depression than those who graduated from university or higher (high school: OR 1.44, 95% CI 1.29-1.60, P value < .001; middle school: OR 1.74, 95% CI 1.52-2.00, P value < .001). Males who reported their employment status as office worker or site worker had significantly lower odds of physician-diagnosed depression (office worker: OR 0.56, 95% CI 0.46-0.67, P value < .001; site worker: OR 0.58, 95% CI 0.50-0.69, P value < .001) than males who reported their employment status as unemployed/homemaker. Female respondents who reported their employment status as office worker or site worker also had significantly lower odds of physician-diagnosed depression (office worker: OR 0.63, 95% CI 0.58-0.69, P value < .001; site worker: OR 0.80, 95% CI 0.73-0.87, P value < 0.001) than those who reported their employment status as unemployed/homemaker. In addition, males who lived with their married spouse had significantly lower odds of physician-diagnosed depression (OR 0.47, 95% CI 0.38-0.58, P value < 0.001) than males who were single. The odds of physician-diagnosed depression also was higher for female respondents who lived with their married spouse (OR 1.45, 95% CI 1.26-1.67, P value < .001) compared with female respondents who were single.

Table 4 reports the logistic regression results for all variables stratified by family income level. Among respondents who reported the lowest family income level (fourth quartile), males who resided with a patient having dementia had significantly higher odds of physician-diagnosed depression than males who did not reside with a patient with dementia (OR 1.67, 95% CI 1.08-2.59, P value = .022). In contrast, among respondents who reported the highest family income level (1st quartile), females who resided with a patient having dementia had increased odds of diagnosed depression compared with females who did not reside with a patient having dementia (OR 2.37, 95% CI 1.36-4.14, P value = .002).

Table 4.

Adjusted Odds Ratios and 95% CI for the Existence of Physician-Diagnosed Depression for Each Variable by Family Income Level.a

1 Q (highest) 2 Q 3 Q 4 Q (lowest)
OR 95% CI P Value OR 95% CI P Value OR 95% CI P Value OR 95% CI P Value
Male
 Cohabitation with a patient with dementia Yes 1.60 0.54-4.74 .394 0.84 0.31-2.29 .737 0.69 0.29-1.65 .405 1.67 1.08-2.59 .022
No 1.00 1.00 1.00 1.00
Female
 Cohabitation with a patient with dementia Yes 2.37 1.36-4.14 .002 1.07 0.61-1.86 .826 0.99 0.98-1.00 .253 1.23 0.90-1.68 .196
No 1.00 1.00 1.00 1.00
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Abbreviation: OR, odds ratio; CI, confidence interval.

aAdjusted for age, employment status, education level, marital status, number of family members, insurance type, self-reported health condition, self-reported stress, smoking habit, alcohol use, hours of sleep per night, underlying chronic disease, and survey year.

Discussion

In the current study, we analyzed 457 864 participants, 5360 of whom resided with a family member with dementia, to assess whether family members who provide care for a family member with dementia are at a higher risk of physician-diagnosed depression than those who do not reside with a family member with dementia. The results of this study have revealed that female caregivers who reside with a family member with dementia are at increased risk of physician-diagnosed depression. This increase in risk was not observed in male caregivers who reside with a family member with dementia.

This result is consistent with the results of previous studies. According to a systematic review by Cuijpers, 33 the relative risk of depressive disorder among dementia caregivers is 2.80 to 38.68, compared with the general population. The studies included in this systematic review, however, had small sample sizes and therefore were not representative of the Korean population. The finding in the current study that the prevalence of depression is higher in females than males is consistent with a previous study by Mahoney et al. 34 In particular, males who reside with their married spouse have decreased odds (ie, OR < 1.00) of physician-diagnosed depression compared with single males, whereas females who reside with their married spouse have increased odds for physician-diagnosed depression compared with single females.

This would be due to the role difference between male and female in family. According to Brodaty et al 15 the largest proportion of those caregivers was spouses, followed by children and children-in-law, mostly female. By the Pearlin et al 35 model of caregiver strain, this role difference would make a result of this study. In Korea, the role of female member on family care is further dominant than male because of Confucian culture. So the difference of caregiving burden might have influenced to this result.

Further differences emerged when the data were stratified by family income level. The results of the current study indicate that financial status differentially impacts the prevalence of depression among dementia caregivers. The risk of physician-diagnosed depression among males who resided with a patient with dementia was highest among those who reported a low family income level. In contrast, however, the risk of physician-diagnosed depression was highest in females who reported a high family income level. These results may be explained by the traditional gender roles in Korea, in which males provide primarily economic support and females provide primarily home-based support. So, males in low-income family would have financial stress for cost of caregiving than who are in high-income family. In the case of female, it would need to further study for interpretation. One of the possible reasons for more depression in high-income family female caregiver comparing with low-income family female is difference of opportunity cost of caregiving between high-income family female and low-income family female. Future studies should investigate the additional factors that impact the risk of physician-diagnosed depression among male versus female dementia caregivers.

Limitations

The current study has several limitations. First, the exact relationship between the patient with dementia and the caregiver is unknown. Most older adults with dementia receive assistance from their spouse, but adult children also serve as the caregiver when the spouse is no longer alive or is unavailable to provide assistance. 36 According to a study by Andren et al, 37 the perceived health of the caregiver varies with the level of burden on the caregiver. This burden is not equally shared by all family members, and therefore the relationship with the patient with dementia may have an important impact on perceived health. 37,38

A second limitation of this study is that no information about the severity or duration of dementia in the sick family member was available. Participants in this study may have been influenced by the severity of dementia in the patient. Because this study analyzed the association between depression and cohabitation with a family member with dementia rather than factors that affect the caregiver, the results of this study would have a unique interpretation for the Korean population.

A third limitation of this study is that we used survey data rather than medical records to confirm a diagnosis of depression. This self-report of physician-diagnosed depression may introduce recall bias to the data. This survey, however, was conducted by a trustworthy national institution, the Korean Centers for Disease Control and Prevention, using skilled interviewers and a computer-based system. We do not suspect, therefore, that the self-report of physician-diagnosed depression has a significant effect on the results of this study.

Last, this study evaluated the effects only for caregivers who were family member of a patient with dementia. The effect on the other caregiver is also very interesting and need to be evaluated. But in our dataset, we cannot distinguish caregivers who are doing it as a job or else formal caregivers. In further study, it would be necessary to study the impact of dementia caregiving on the formal caregiver.

Conclusion

The results of this study confirm an association between physician-diagnosed depression and cohabitation with a patient with dementia. In particular, high-income females and low-income males who reside with a patient with dementia are at a significantly increased risk of diagnosed depression. To reduce the burden of dementia, we need a management policy that includes the caregiver as well as the patient with dementia. This policy should focus in particular on female caregivers as well as male caregivers who have a low-family income level.

Footnotes

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding: The authors received no financial support for the research, authorship, and/or publication of this article.

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