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Geriatr Gerontol Int 2015; 15: 707–714
ORIGINAL ARTICLE: EPIDEMIOLOGY, CLINICAL PRACTICE AND HEALTH
Personal mastery, multisystem physiological dysregulation and risk of functional decline in older adults: A prospective study in Taiwan I-Chien Wu,1,2 Chao A Hsiung,1 I-Shou Chang,3 Ming-Shiang Wu,1 Yu-Hung Chang4 and Chih-Cheng Hsu1,5 1
Institute of Population Health Sciences, National Health Research Institutes, Miaoli County, 3Institute of Cancer Research and Division of Biostatistics and Bioinformatics, National Health Research Institutes, Miaoli County, 2Program for Aging, College of Medicine, 4Department of Public Health, China Medical University, Taichung, Taiwan, and 5Department of Health Services Administration, China Medical University and Hospital, Taichung, Taiwan
Aim: Personal mastery has been associated with physical function maintenance later in life. Less is known about the relationship between lack of personal mastery and functional decline in Asian populations, and whether multisystem physiological dysregulation explains this relationship. Methods: Participants (n = 487) from the Social Environment and Biomarkers of Aging Study, a population-based prospective cohort study in Taiwan, received baseline measurements of personal mastery using the Pearlin Mastery Scale. Multisystem physiological dysregulation at baseline was assessed as a summary score based on the levels of 16 biomarkers of the hypothalamic–pituitary–adrenal axis, the sympathetic nervous system, the cardiovascular system, the metabolic system and the immune system functioning. Function in activities of daily living was determined at baseline and at a 7-year follow up. Results: Participants in the lowest quartile of the personal mastery score were more likely to experience functional decline than those in the higher quartiles (OR comparing the lowest with highest 3 quartiles 2.99, 95% CI 1.71–5.21). After adjusting for confounders, personal mastery remained significantly associated with functional changes (adjusted OR 2.09, 95% CI 1.05–4.14). Greater sense of personal mastery was associated with significantly less multisystem physiological dysregulation (P for trend = 0.001). When the levels of physiological dysregulation were added to the multivariate models, the association between a poor sense of personal mastery and functional decline was attenuated. Conclusions: Lack of personal mastery is independently associated with an increased risk of functional decline in older adults. Multisystem physiological dysregulation partially explains this relationship. Geriatr Gerontol Int 2015; 15: 707–714. Keywords: aging, frail elderly, mental health, mobility limitation, physiology.
Introduction Disability is a major health issue in the aging population.1 Disability is common in older adults, and is associated with mortality, institutionalization and high healthcare needs.1,2 With the global population aging at unprecedented rates, strategies aimed at preventing,
Accepted for publication 5 May 2014. Correspondence: Professor Chih-Cheng Hsu MD DRPH, Institute of Population Health Sciences, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 35053, Taiwan. Email: [email protected]
© 2014 Japan Geriatrics Society
delaying and reversing decline in physical functioning at old age are urgently required. To obtain this goal, a high priority is in identifying mechanisms protecting against the disablement process. Recent evidence suggests that mental health could have protective effects on physical functioning.3 Personal mastery, defined as the “extent to which one regards one’s life-chances as being under one’s own control in contrast to being fatalistically ruled”,4,5 has been shown to have multiple health benefits.6–10 However, this psychological attribute declines with age.11 Recent studies have shown that older adults with lower personal mastery were at greater risk of impaired physical functioning.12,13 Milaneschi et al. further showed that poorer personal mastery is associated with doi: 10.1111/ggi.12334
| 707
I-C Wu et al.
a greater degree of lower extremity functional impairment.14 However, whether the relationship between personal mastery and late life health could be observed in populations of different ethnicities or cultures remains unknown.15 Furthermore, the detailed mechanisms underlying the observed association between control belief and physical function maintenance in elderly people are unclear. Personal mastery might directly modulate the activities of multiple physiological systems involved in stress response, including the hypothalamic–pituitary–adrenal (HPA) axis, the sympathetic nervous system, the cardiovascular system, the metabolic system and the immune system, thereby buffering the deleterious effects of prolonged or repetitive stress on the body.8,16,17 The cumulative multisystem dysregulation (physiological burden) resulting from the body’s response to prolonged or recurrent stress over time has been shown to be strongly and independently associated with multiple adverse health outcomes including functional decline in older adults.18–20 Therefore, the multisystem physiological dysregulation could explain the relationship between personal mastery and physical functioning. To clarify whether control belief protects against the decline in physical functioning at old age, we examined the relationship among personal mastery, multisystem physiological dysregulation and future functional changes in a cohort of older Taiwanese people. We hypothesized that a poor sense of personal mastery would be associated with functional decline. We also hypothesized that the relationship between poor personal mastery and functional decline is partially explained by the multisystem physiological dysregulation.
Methods
entry and received standardized examinations during a baseline assessment in 2000, which included a face-toface in-home interview and a clinical assessment. The following information was obtained during the home interview: sociodemographic status, chronic health conditions, physical functioning and psychological well-being. During the clinical assessment, participants underwent a physical examination that included standardized anthropometry and blood pressure measurements. A fasting blood sample and a 12-h urine specimen were also collected. All blood and urine sample analyses were carried out in the central laboratory. During the TLSA follow-up survey in 2007, survivors were re-interviewed. The present study was approved by the institutional review boards of the Bureau of Health Promotion in Taiwan, Princeton University (Princeton, New Jersey) and Georgetown University (Washington, DC). Among the 1713 respondents of the 1999 wave of the TLSA who were selected for the SEBAS, 1497 participants (92% of survivors) underwent interviews, and 1023 participants (68% of those interviewed) participated in the clinical assessments. Details of the study participation have been described elsewhere.22–24 Among the 1023 participants who underwent a complete SEBAS baseline assessment in 2000, 15 (1.5%) had missing personal mastery scores, 271 (26.5%) did not have complete information on 16 biomarkers, 203 (19.8%) died before the follow-up survey in 2007 and 47 (4.6%) were lost to follow up. Our analytic cohort was limited to 487 participants with complete information on personal mastery, biomarkers and follow-up functional status. Although those who were excluded were significantly older (69.0 vs 66.9 years) and more often men (63.1% vs 54.8%), they did not differ significantly from these 487 participants in terms of education level, chronic diseases and disability.
Participants Data for these analyses were retrieved from the Social Environment and Biomarkers of Aging Study (SEBAS), a population-based cohort study that started in 2000 as an extension of the Taiwan Longitudinal Study of Aging (TLSA). The sampling and data collection procedures of the TLSA and the SEBAS have previously been described in depth.21–24 The TLSA is a longitudinal survey that began in 1989 with the recruitment of a nationally representative sample of older adults. Since 1989, participants were interviewed at 2- to 3-year intervals, during which data on health-related behaviors and physical functioning were collected. The study population of the SEBAS consists of adults aged 54 years and older who were randomly selected from respondents to the 1999 wave of the TLSA. Respondents aged 71 years and older and those in urban areas were oversampled. Participants signed informed consent forms at the study 708 |
Personal mastery at baseline Personal mastery was assessed using the four-point, seven-item Likert-type Pearlin Mastery Scale (Pearlin and Schooler, 1978), which is a valid and reliable measure of mastery,4,5,24 ranging from 1 (strongly agree) to 4 (strongly disagree). A total score was calculated by adding the scores for the seven items, and range from 7 to 28, with a higher score indicating a greater sense of mastery. The scale had reasonable reliability in our sample (α = 0.65).
Multisystem physiological dysregulation at baseline The degree of multisystem physiological dysregulation was assessed as a summary score by using the index developed by Goldman et al., which is a modified version of the original allostatic load index.18–20 The index is © 2014 Japan Geriatrics Society
Personal mastery, biomarkers and disability
designed to summarize levels of physiological activity of a range of regulatory systems important in maintaining health at old age, including the HPA axis, the sympathetic nervous system, the cardiovascular system, the metabolic system and the immune system. The summary score was calculated by summing the number of the following 16 criteria that were present: systolic blood pressure >166 mmHg or 97 mmHg or 28.9 kg/m2 or 1.0 or 252.0 mg/dL or 6.1; serum triglycerides >204.0 mg/dL or 138.0 mg/dL or 7.1% or 226.7 μg/g of creatinine or 3.4 pg/mL or undetectable; and serum insulin-like growth factor 1 (IGF-1) >168.0 ng/ mL or 9 years), smoking status (smoker or non-smoker), alcohol intake (non-drinker, light drinker or moderate to heavy drinker), exercise (less than once per week, once to five times per week or at least six times per week), comorbidities (diabetes mellitus, hypertension, stroke, cardiovascular disease and arthritis), the number of baseline ADL difficulties and depressed mood. Participants who reported smoking cigarettes at the time of the interview were defined as smokers. Alcohol use was classified as follows: non-drinker (less than once per month), light drinker (at least once per month, but not every day) and moderate to heavy drinker (every day). Diabetes mellitus was defined by a self-report, medication use, fasting plasma glucose of 126 mg/dL or greater or glycosylated hemoglobin of 6.5% or greater.29 Other | 709
I-C Wu et al.
comorbidities were assessed by a self-reported physician’s diagnosis, and included hypertension, stroke, cardiovascular disease and arthritis. Depressed mood at baseline was assessed using the 10-item version of the Center for Epidemiological Studies Depression Scale.30 A depressed mood was defined with a score of 10 or greater.30 All of the covariates were assessed during the baseline assessment in 2000.
Statistical analysis We calculated the descriptive statistics to characterize the population. The results for all continuous variables are presented as mean ± SD. Differences in continuous variables among groups were analyzed using one-way analysis of variance (ANOVA), and differences in categorical variables (proportions) were analyzed using χ2-tests. Associations between personal mastery score and levels of physiological dysregulation at baseline were examined using general linear models. We carried out multinomial logistic regression analysis to examine whether, compared with people with a high personal mastery score (baseline personal mastery score in the highest three quartiles), their low-score counterparts (baseline personal mastery score in the lowest quartile) had higher odds of experiencing functional decline. We made adjustments for four models, with each successive model repeating the adjustments of the previous model, as follows: model 1 (adjusted for age, sex and education level), model 2 (same adjustments as model 1, in addition to adjustment for smoking, alcohol use, exercise, comorbidities, and the number of baseline ADL difficulties) and model 3 (same adjustments as model 2, in addition to adjustment for depressed mood). To assess whether the increased risk of functional decline associated with a low personal mastery score was explained by the multisystem physiological dysregulation, we examined the relationship between personal mastery and functional decline after further adjusting for the levels of physiological dysregulation score at baseline (model 4). For all analyses, differences were considered significant if P < 0.05. We calculated 95% confidence intervals (CI) and reported the CI for each parameter estimate. All the analyses were carried out using SPSS version 19.0 (SPSS, Chicago, IL, USA).
Results Table 1 shows the baseline characteristics of the study population. For baseline personal mastery scores, the mean ± SD was 18.4 ± 2.7. Participants with a low personal mastery score were more likely to be women, less educated, smokers, and tended to have comorbid conditions, depressed mood and a greater degree of baseline 710 |
functional impairment. Of note, participants with a poor sense of personal mastery had a higher physiological dysregulation score (Table 1). Sense of personal mastery was associated with significantly less multisystem physiological dysregulation (Fig. 1). Participants in the lowest quartile of the personal mastery score at baseline were more likely to experience functional decline during follow up compared with those in the higher quartiles (Table 2). Personal mastery remained significantly associated with functional changes after adjusting for age, sex and education level (model 1, P = 0.002; Table 2). With further adjustments for health-related behaviors, comorbidities and the number of baseline ADL difficulties, a poor sense of personal mastery was still associated with greater odds in functional decline (model 2, P = 0.006; Table 2). Older adults with a poor sense of personal mastery were 2.51-fold more likely than those with a greater sense of mastery to experience a decline in function after 7 years. To determine if any relationships exist between personal mastery and physical functioning, independent of depressed mood, we repeated the analysis after controlling for depressed mood. A poor sense of personal mastery remained significantly associated with functional decline (model 3, P = 0.036; Table 2). To address whether multisystem physiological dysregulation might account for the relationship between a poor sense of personal mastery and functional decline, we added this variable to the multivariable models. After adjusting for the physiological dysregulation score, the association between a poor sense of personal mastery and functional decline was attenuated (model 4, P = 0.050; Table 2).
Discussion In the present prospective study of older adults in Taiwan, we found that a poor sense of personal mastery is a risk factor of future functional decline. This finding persisted after adjusting for major confounders. The relationship between personal mastery and functional changes was attenuated after the control for physiological dysregulation score, which suggests that a multisystem physiological dysregulation could account for the excess odds of functional decline associated with a poor personal mastery. The results of the present study shed light on novel mechanisms protecting against the disablement process. Our study showed that older adults with a greater sense of personal mastery were less likely than those with a poor sense of mastery to experience functional decline after 7 years. The present results were consistent with Western studies.12–14 Kempen et al. showed that older Netherlanders with low levels of personal mastery were at high risk of disability.12 Milaneschi et al. showed that, in an Italian population, a © 2014 Japan Geriatrics Society
Personal mastery, biomarkers and disability
Table 1 Characteristics of study participants according to personal mastery status Characteristics
All participants (n = 487)
Low personal mastery† (n = 104)
High personal mastery‡ (n = 383)
P§
Age (years) Female, n (%) Education
Geriatr Gerontol Int 2015; 15: 707–714
ORIGINAL ARTICLE: EPIDEMIOLOGY, CLINICAL PRACTICE AND HEALTH
Personal mastery, multisystem physiological dysregulation and risk of functional decline in older adults: A prospective study in Taiwan I-Chien Wu,1,2 Chao A Hsiung,1 I-Shou Chang,3 Ming-Shiang Wu,1 Yu-Hung Chang4 and Chih-Cheng Hsu1,5 1
Institute of Population Health Sciences, National Health Research Institutes, Miaoli County, 3Institute of Cancer Research and Division of Biostatistics and Bioinformatics, National Health Research Institutes, Miaoli County, 2Program for Aging, College of Medicine, 4Department of Public Health, China Medical University, Taichung, Taiwan, and 5Department of Health Services Administration, China Medical University and Hospital, Taichung, Taiwan
Aim: Personal mastery has been associated with physical function maintenance later in life. Less is known about the relationship between lack of personal mastery and functional decline in Asian populations, and whether multisystem physiological dysregulation explains this relationship. Methods: Participants (n = 487) from the Social Environment and Biomarkers of Aging Study, a population-based prospective cohort study in Taiwan, received baseline measurements of personal mastery using the Pearlin Mastery Scale. Multisystem physiological dysregulation at baseline was assessed as a summary score based on the levels of 16 biomarkers of the hypothalamic–pituitary–adrenal axis, the sympathetic nervous system, the cardiovascular system, the metabolic system and the immune system functioning. Function in activities of daily living was determined at baseline and at a 7-year follow up. Results: Participants in the lowest quartile of the personal mastery score were more likely to experience functional decline than those in the higher quartiles (OR comparing the lowest with highest 3 quartiles 2.99, 95% CI 1.71–5.21). After adjusting for confounders, personal mastery remained significantly associated with functional changes (adjusted OR 2.09, 95% CI 1.05–4.14). Greater sense of personal mastery was associated with significantly less multisystem physiological dysregulation (P for trend = 0.001). When the levels of physiological dysregulation were added to the multivariate models, the association between a poor sense of personal mastery and functional decline was attenuated. Conclusions: Lack of personal mastery is independently associated with an increased risk of functional decline in older adults. Multisystem physiological dysregulation partially explains this relationship. Geriatr Gerontol Int 2015; 15: 707–714. Keywords: aging, frail elderly, mental health, mobility limitation, physiology.
Introduction Disability is a major health issue in the aging population.1 Disability is common in older adults, and is associated with mortality, institutionalization and high healthcare needs.1,2 With the global population aging at unprecedented rates, strategies aimed at preventing,
Accepted for publication 5 May 2014. Correspondence: Professor Chih-Cheng Hsu MD DRPH, Institute of Population Health Sciences, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 35053, Taiwan. Email: [email protected]
© 2014 Japan Geriatrics Society
delaying and reversing decline in physical functioning at old age are urgently required. To obtain this goal, a high priority is in identifying mechanisms protecting against the disablement process. Recent evidence suggests that mental health could have protective effects on physical functioning.3 Personal mastery, defined as the “extent to which one regards one’s life-chances as being under one’s own control in contrast to being fatalistically ruled”,4,5 has been shown to have multiple health benefits.6–10 However, this psychological attribute declines with age.11 Recent studies have shown that older adults with lower personal mastery were at greater risk of impaired physical functioning.12,13 Milaneschi et al. further showed that poorer personal mastery is associated with doi: 10.1111/ggi.12334
| 707
I-C Wu et al.
a greater degree of lower extremity functional impairment.14 However, whether the relationship between personal mastery and late life health could be observed in populations of different ethnicities or cultures remains unknown.15 Furthermore, the detailed mechanisms underlying the observed association between control belief and physical function maintenance in elderly people are unclear. Personal mastery might directly modulate the activities of multiple physiological systems involved in stress response, including the hypothalamic–pituitary–adrenal (HPA) axis, the sympathetic nervous system, the cardiovascular system, the metabolic system and the immune system, thereby buffering the deleterious effects of prolonged or repetitive stress on the body.8,16,17 The cumulative multisystem dysregulation (physiological burden) resulting from the body’s response to prolonged or recurrent stress over time has been shown to be strongly and independently associated with multiple adverse health outcomes including functional decline in older adults.18–20 Therefore, the multisystem physiological dysregulation could explain the relationship between personal mastery and physical functioning. To clarify whether control belief protects against the decline in physical functioning at old age, we examined the relationship among personal mastery, multisystem physiological dysregulation and future functional changes in a cohort of older Taiwanese people. We hypothesized that a poor sense of personal mastery would be associated with functional decline. We also hypothesized that the relationship between poor personal mastery and functional decline is partially explained by the multisystem physiological dysregulation.
Methods
entry and received standardized examinations during a baseline assessment in 2000, which included a face-toface in-home interview and a clinical assessment. The following information was obtained during the home interview: sociodemographic status, chronic health conditions, physical functioning and psychological well-being. During the clinical assessment, participants underwent a physical examination that included standardized anthropometry and blood pressure measurements. A fasting blood sample and a 12-h urine specimen were also collected. All blood and urine sample analyses were carried out in the central laboratory. During the TLSA follow-up survey in 2007, survivors were re-interviewed. The present study was approved by the institutional review boards of the Bureau of Health Promotion in Taiwan, Princeton University (Princeton, New Jersey) and Georgetown University (Washington, DC). Among the 1713 respondents of the 1999 wave of the TLSA who were selected for the SEBAS, 1497 participants (92% of survivors) underwent interviews, and 1023 participants (68% of those interviewed) participated in the clinical assessments. Details of the study participation have been described elsewhere.22–24 Among the 1023 participants who underwent a complete SEBAS baseline assessment in 2000, 15 (1.5%) had missing personal mastery scores, 271 (26.5%) did not have complete information on 16 biomarkers, 203 (19.8%) died before the follow-up survey in 2007 and 47 (4.6%) were lost to follow up. Our analytic cohort was limited to 487 participants with complete information on personal mastery, biomarkers and follow-up functional status. Although those who were excluded were significantly older (69.0 vs 66.9 years) and more often men (63.1% vs 54.8%), they did not differ significantly from these 487 participants in terms of education level, chronic diseases and disability.
Participants Data for these analyses were retrieved from the Social Environment and Biomarkers of Aging Study (SEBAS), a population-based cohort study that started in 2000 as an extension of the Taiwan Longitudinal Study of Aging (TLSA). The sampling and data collection procedures of the TLSA and the SEBAS have previously been described in depth.21–24 The TLSA is a longitudinal survey that began in 1989 with the recruitment of a nationally representative sample of older adults. Since 1989, participants were interviewed at 2- to 3-year intervals, during which data on health-related behaviors and physical functioning were collected. The study population of the SEBAS consists of adults aged 54 years and older who were randomly selected from respondents to the 1999 wave of the TLSA. Respondents aged 71 years and older and those in urban areas were oversampled. Participants signed informed consent forms at the study 708 |
Personal mastery at baseline Personal mastery was assessed using the four-point, seven-item Likert-type Pearlin Mastery Scale (Pearlin and Schooler, 1978), which is a valid and reliable measure of mastery,4,5,24 ranging from 1 (strongly agree) to 4 (strongly disagree). A total score was calculated by adding the scores for the seven items, and range from 7 to 28, with a higher score indicating a greater sense of mastery. The scale had reasonable reliability in our sample (α = 0.65).
Multisystem physiological dysregulation at baseline The degree of multisystem physiological dysregulation was assessed as a summary score by using the index developed by Goldman et al., which is a modified version of the original allostatic load index.18–20 The index is © 2014 Japan Geriatrics Society
Personal mastery, biomarkers and disability
designed to summarize levels of physiological activity of a range of regulatory systems important in maintaining health at old age, including the HPA axis, the sympathetic nervous system, the cardiovascular system, the metabolic system and the immune system. The summary score was calculated by summing the number of the following 16 criteria that were present: systolic blood pressure >166 mmHg or 97 mmHg or 28.9 kg/m2 or 1.0 or 252.0 mg/dL or 6.1; serum triglycerides >204.0 mg/dL or 138.0 mg/dL or 7.1% or 226.7 μg/g of creatinine or 3.4 pg/mL or undetectable; and serum insulin-like growth factor 1 (IGF-1) >168.0 ng/ mL or 9 years), smoking status (smoker or non-smoker), alcohol intake (non-drinker, light drinker or moderate to heavy drinker), exercise (less than once per week, once to five times per week or at least six times per week), comorbidities (diabetes mellitus, hypertension, stroke, cardiovascular disease and arthritis), the number of baseline ADL difficulties and depressed mood. Participants who reported smoking cigarettes at the time of the interview were defined as smokers. Alcohol use was classified as follows: non-drinker (less than once per month), light drinker (at least once per month, but not every day) and moderate to heavy drinker (every day). Diabetes mellitus was defined by a self-report, medication use, fasting plasma glucose of 126 mg/dL or greater or glycosylated hemoglobin of 6.5% or greater.29 Other | 709
I-C Wu et al.
comorbidities were assessed by a self-reported physician’s diagnosis, and included hypertension, stroke, cardiovascular disease and arthritis. Depressed mood at baseline was assessed using the 10-item version of the Center for Epidemiological Studies Depression Scale.30 A depressed mood was defined with a score of 10 or greater.30 All of the covariates were assessed during the baseline assessment in 2000.
Statistical analysis We calculated the descriptive statistics to characterize the population. The results for all continuous variables are presented as mean ± SD. Differences in continuous variables among groups were analyzed using one-way analysis of variance (ANOVA), and differences in categorical variables (proportions) were analyzed using χ2-tests. Associations between personal mastery score and levels of physiological dysregulation at baseline were examined using general linear models. We carried out multinomial logistic regression analysis to examine whether, compared with people with a high personal mastery score (baseline personal mastery score in the highest three quartiles), their low-score counterparts (baseline personal mastery score in the lowest quartile) had higher odds of experiencing functional decline. We made adjustments for four models, with each successive model repeating the adjustments of the previous model, as follows: model 1 (adjusted for age, sex and education level), model 2 (same adjustments as model 1, in addition to adjustment for smoking, alcohol use, exercise, comorbidities, and the number of baseline ADL difficulties) and model 3 (same adjustments as model 2, in addition to adjustment for depressed mood). To assess whether the increased risk of functional decline associated with a low personal mastery score was explained by the multisystem physiological dysregulation, we examined the relationship between personal mastery and functional decline after further adjusting for the levels of physiological dysregulation score at baseline (model 4). For all analyses, differences were considered significant if P < 0.05. We calculated 95% confidence intervals (CI) and reported the CI for each parameter estimate. All the analyses were carried out using SPSS version 19.0 (SPSS, Chicago, IL, USA).
Results Table 1 shows the baseline characteristics of the study population. For baseline personal mastery scores, the mean ± SD was 18.4 ± 2.7. Participants with a low personal mastery score were more likely to be women, less educated, smokers, and tended to have comorbid conditions, depressed mood and a greater degree of baseline 710 |
functional impairment. Of note, participants with a poor sense of personal mastery had a higher physiological dysregulation score (Table 1). Sense of personal mastery was associated with significantly less multisystem physiological dysregulation (Fig. 1). Participants in the lowest quartile of the personal mastery score at baseline were more likely to experience functional decline during follow up compared with those in the higher quartiles (Table 2). Personal mastery remained significantly associated with functional changes after adjusting for age, sex and education level (model 1, P = 0.002; Table 2). With further adjustments for health-related behaviors, comorbidities and the number of baseline ADL difficulties, a poor sense of personal mastery was still associated with greater odds in functional decline (model 2, P = 0.006; Table 2). Older adults with a poor sense of personal mastery were 2.51-fold more likely than those with a greater sense of mastery to experience a decline in function after 7 years. To determine if any relationships exist between personal mastery and physical functioning, independent of depressed mood, we repeated the analysis after controlling for depressed mood. A poor sense of personal mastery remained significantly associated with functional decline (model 3, P = 0.036; Table 2). To address whether multisystem physiological dysregulation might account for the relationship between a poor sense of personal mastery and functional decline, we added this variable to the multivariable models. After adjusting for the physiological dysregulation score, the association between a poor sense of personal mastery and functional decline was attenuated (model 4, P = 0.050; Table 2).
Discussion In the present prospective study of older adults in Taiwan, we found that a poor sense of personal mastery is a risk factor of future functional decline. This finding persisted after adjusting for major confounders. The relationship between personal mastery and functional changes was attenuated after the control for physiological dysregulation score, which suggests that a multisystem physiological dysregulation could account for the excess odds of functional decline associated with a poor personal mastery. The results of the present study shed light on novel mechanisms protecting against the disablement process. Our study showed that older adults with a greater sense of personal mastery were less likely than those with a poor sense of mastery to experience functional decline after 7 years. The present results were consistent with Western studies.12–14 Kempen et al. showed that older Netherlanders with low levels of personal mastery were at high risk of disability.12 Milaneschi et al. showed that, in an Italian population, a © 2014 Japan Geriatrics Society
Personal mastery, biomarkers and disability
Table 1 Characteristics of study participants according to personal mastery status Characteristics
All participants (n = 487)
Low personal mastery† (n = 104)
High personal mastery‡ (n = 383)
P§
Age (years) Female, n (%) Education
