Fatigue and Depressive Symptoms in Older People

Abstract

Fatigue is considered an important indicator of aging-related declines in health and functional abilities. Previous studies have indicated strong associations between fatigue and depressive symptoms among younger populations and in patient groups with specific diseases. However, it is not known how different measures of fatigue are associated with depressive symptoms among general older populations. The purpose of this study is to describe the prevalence of depressive symptoms among community-dwelling older adults reporting mobility-related or general feelings fatigue. The study population consisted of 75-year-old community-living individuals (n = 561). Both, mobility-related and general fatigue, were associated in a stepwise relationship with depressive symptoms: a higher level of fatigue was related to higher level of depressive symptoms. Especially major general fatigue was strongly associated with high level of depressive symptoms. It is important for professionals of the field to be aware of the associations between different measures of fatigue and depressive symptoms.

Keywords

fatigue depressive symptoms aging

Introduction

There has been a growing interest in fatigue as an early marker of aging-related declines in health and functional abilities (Avlund, 2010). Fatigue is a commonly reported symptom in older people, which has been associated with sedentary lifestyle, poor functional performance, and higher levels of disability (Avlund, Rantanen, & Schroll, 2006; Hardy & Studenski, 2008; Mänty et al., 2012, Vestergaard et al., 2009). Previous studies have also indicated strong associations between fatigue and depressive symptoms among younger general populations (Addington, Gallo, Ford, & Eaton, 2001; Lin et al., 2009; Watt et al., 2000), primary care patients (Skapinakis, Lewis, & Mavreas, 2003, 2004), and in patients with a specific condition, such as, cancer (Brown & Kroenke, 2009), multiple sclerosis (Bakshi et al., 2000; Pittion-Vouyovitch et al., 2006), or chronic pulmonary disease (Breslin et al., 1998). However, the association between unexplained fatigue and depressive symptoms has rarely been reported among general community-dwelling older adults. Furthermore, during recent decades fatigue has been conceptualized using various definitions, and several measures of fatigue have been developed, ranging from simple global questions on general fatigue to more complex and specified measures of physical or mental fatigue (Avlund, 2010; Watt et al., 2000). It has been suggested that general or mental fatigue might be more strongly associated with depressive symptoms as compared to feelings of fatigue relating to physical function (Watt et al., 2000). However, only a few studies have been carried out to investigate this issue (Breslin et al., 1998; Watt et al., 2000) and none of these among older populations. The objective of this study was to describe the prevalence of depressive symptoms among older community-dwelling adults reporting mobility-related or general feelings fatigue.

Method

Participants

This descriptive cross-sectional study is based on baseline data of the Nordic Research on Aging Study (NORA; Kauppinen, Davidsen, & Sundh, 2002). The original study population (n = 835) consisted of a random sample of 75-year-old persons living in Glostrup, Denmark (n = 480) and of all 75-year-old citizens living in Jyväskylä, Finland (n = 355). Of the original study population, 20% did not have independent mobility and 11% to 13% lacked information on depressive symptoms, diseases, or general fatigue, leaving 561 participants (55% women) for the analyses. The selected participants tended to have slightly better health and physical function as compared to nonparticipants (data not shown).

Materials and Procedure

At both sites, all assessments were carried out using identical standard protocols. Face-to-face interviews were conducted at participants’ homes and included structured questions on depressive symptoms, fatigue and other covariates.

Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (CES-D, score range 0-60) with a cutoff score of ≥ 16 to identify subjects with depressed mood (Radloff, 1977).

Mobility-related fatigue was measured using a structured and previously validated instrument, the Mobility-Tiredness Scale (MOB-T: Avlund, Kreiner, & Schultz-Larsen, 1996). Participants were asked whether they felt fatigued after performing six mobility tasks: rising from a chair or bed, walking indoors, getting outdoors, walking outdoors in a nice weather, walking outdoors in a bad weather, and climbing stairs. Answers were summed for a total fatigue score (range 0-6), with higher scores indicating higher levels of fatigue. For the purpose of this study, we computed a categorical fatigue variable to explore the possible gradient association between fatigue and depressive symptoms: (1) No fatigue, (2) fatigue in 1 to 3 tasks and (3) fatigue in 4 to 6 tasks.

The level of general fatigue was evaluated with a structured question on experienced feelings of general fatigue during the past 14 days using the following categorization; (1) No fatigue, (2) minor fatigue (a little) and (3) major fatigue (a lot).

Information on the number of chronic diseases was checked during the medical examination by a physician. Income was defined as low (only compulsory old age pension) versus high (compulsory old age pension plus other sources of income).

Statistical Analyses

The associations between mobility-related and general fatigue with depressive symptoms were examined using Kruskal-Wallis test, chi-square test and logistic regression. Regression models were adjusted for gender, geographic location, number of chronic diseases, and income. Gender-by-fatigue interactions on depression were found to be nonsignificant (all p values >.05), and therefore the primary analyses were performed in men and women combined. However, we performed secondary analyses stratified by gender due to previously observed significant gender differences in fatigue and depression. All analyses were performed using SAS software version 9.2 (SAS Institute Inc., Cary, NC).

Results

Fatigue was common in this study population. 56% of the participants reported mobility related fatigue; 30% in 1 to 3 tasks and 26% in 4 to 6 tasks. Respectively, 38% of the participants reported general fatigue: 31% minor and 7% major general fatigue.

Depressive symptoms according to level of fatigue are presented in Table 1. Overall, the mean CES-D score was 10.5 (SD 8.5) and the proportion of participants having depressive mood 24%. Mean CES-D score as well as the proportion of those reporting depressed mood (CES-D ≥ 16) were significantly higher among participants reporting higher levels of both types of fatigue (Table 1). Participants reporting mobility-related fatigue in 1 to 3 tasks were around two times more likely (OR 2.3, 95% CI [1.4, 3.8]) and those reporting fatigue in 4 to 6 tasks around 4 times more likely (OR 4.3, 95% CI [2.5, 7.3]) to have depressed mood as compared to those reporting no mobility-related fatigue (Table 2). Respectively, participants reporting minor general fatigue were around 3 times (OR 2.9, 95% CI [1.8, 4.7]) and those with major general fatigue over 9 times more likely (OR 9.4, 95% CI [4.3, 20.5]) to have depressed mood as compared to those reporting no general fatigue (Table 2). However, although fatigue was strongly associated with depressive symptoms, over two thirds (62%-71%) of participants reporting mobility-related fatigue and over one third (34%-65%) of those reporting general fatigue did not have depressed mood (Table 1).

Table 1.

Prevalence of Fatigue and Depressive Symptoms According to Fatigue Level.

		Mobility-related fatigue			p ^a	General fatigue			p ^a
		No fatigue	Fatigue in 1-3 tasks	Fatigue in 4-6 tasks	p ^a	No fatigue	Minor fatigue	Major fatigue	p ^a
All
CES-D score, mean (SD)	10.5 (8.5)	8.1 (7.3)	12.4 (8.2)	12.5 (9.8)	<.001	7.9 (6.9)	13.8 (8.9)	19.4 (9.0)	<.001
Depressed mood^b, n (%)	136 (24)	33 (13)	49 (29)	54 (38)	<.001	48 (14)	63 (35)	25 (66)	<.001
Women
CES-D score, mean (SD)	12.2 (8.7)	9.7 (8.1)	13.1 (7.8)	14.3 (9.9)	<.001	9.2 (6.8)	14.6 (9.1)	19.8 (9.2)	<.001
Depressed mood^b, n (%)	88 (28)	18 (16)	34 (31)	36 (43)	<.001	27 (16)	40 (36)	21 (68)	<.001
Men
CES-D score, mean (SD)	8.4 (7.9)	6.7 (6.2)	9.8 (9.2)	10.9 (8.8)	<.001	6.6 (6.8)	12.3 (8.5)	17.7 (8.2)	<.001
Depressed mood^b, n (%)	48 (19)	15 (12)	15 (25)	18 (30)	=.004	21 (12)	23 (34)	4 (57)	<.001

Note: SD = Standard deviation. CES-D = Center for Epidemiological Studies Depression Scale (Radloff, 1977).

Continuous variables were analyzed with Kruskal–Wallis test and discrete variables with chi-square test.

CESD-D score ≥ 16.

Table 2.

Logistic Regression Models Showing Association of Mobility-Related and General Fatigue With Depressed Mood (CESD ≥ 16).

	All (n = 561)		Women (n = 310)		Men (n = 251)
	OR^a (95% CI)	p	OR^b (95% CI)	p	OR^b (95% CI)	p
Mobility-related fatigue
No fatigue	1		1		1
Fatigue in 1-3 tasks	2.3 (1.4, 3.8)	.002	2.1 (1.1, 4.0)	.031	2.5 (1.1, 5.8)	.027
Fatigue in 4-6 tasks	4.3 (2.5, 7.3)	<.001	3.7 (1.8, 7.7)	<.001	4.7 (2.0, 10.9)	<.001
General fatigue
No fatigue	1		1		1
Minor fatigue	2.9 (1.8, 4.7)	<.001	2.4 (1.3, 4.5)	.005	4.1 (2.0, 8.7)	<.001
Major fatigue	9.4 (4.3, 20.5)	<.001	8.0 (3.3, 19.8)	<.001	11.7 (2.3, 59.1)	.003

Adjusted for gender, geographic location, number of chronic diseases and income.

Adjusted for geographic location, number of chronic diseases and income.

Our gender-stratified secondary analyses showed that women reported more fatigue as well as depressive symptoms as compared to men (Table 1). However, the association between fatigue and depression was similar for men and women (Table 2).

Discussion

The findings of this descriptive study indicate that in older adults mobility-related and general fatigue are both associated in a stepwise relationship with depressive symptoms: a higher level of fatigue appeared to be related to a higher level of depressive symptoms. To our knowledge, this is the first study to report the association between two different measures of fatigue and depressive symptoms among community-dwelling older adults. Our results support previous studies with similar findings in younger study populations (Addington et al., 2001; Lin et al., 2009; Skapinakis et al., 2003, 2004; Watt et al., 2000). It has also been suggested that general or mental fatigue might be more strongly associated with depressive symptoms as compared to feelings of fatigue relating to physical function (Breslin et al., 1998; Watt et al., 2000). This was somewhat supported by our study in that especially major general fatigue was more strongly associated with depressive symptoms as compared to mobility-related fatigue.

It is worth to note that a substantial proportion of participants reporting fatigue did not report depressive symptoms. These results together with previous findings (Breslin et al., 1998; Watt et al., 2000) indicate that although fatigue and depression are strongly related, they are still different entities. In particular, specific measures of physical fatigue seem to have weaker association to depressive symptoms as compared to measures of general or mental fatigue (Breslin et al., 1998; Watt et al., 2000). It is plausible, that mobility-related fatigue might reflect more lower physical performance, such as weaker muscle function or aerobic capacity (Avlund, Rantanen, & Schroll, 2007; Mänty et al., 2012), whereas different psychological factors might contribute more to general or mental fatigue. However, these associations need to be clarified in future studies.

The previously observed associations between fatigue and depressive symptoms (Addington et al., 2001; Lin et al., 2009; Skapinakis et al., 2003, 2004; Watt et al., 2000) have given rise to discussions on the nature of the relationship, which may be reciprocal; fatigue is known to be a symptom of depression, but on the other hand, chronic fatigue has been shown to cause depression (Skapinakis et al., 2004). It is also possible that fatigue and depression are conditions that arise concurrently as a result of common underlying pathophysiological process. Furthermore, the association between fatigue and depression might be partly explained by the way these two entities have been conceptualized (Skapinakis et al., 2003). Especially, general and mental fatigue may have problems with overlapping criteria as they are often included in measures of depressive symptoms, whereas this problem is less evident between mobility-related fatigue and depression. Nevertheless, the exact causal associations between fatigue and depression are likely to be complex and studies with more frequent assessments are needed to delineate the exact mechanisms between fatigue and depression.

The NORA data set used in this study consists of participants from two Nordic localities, Jyväskylä, Finland and Glostrup, Denmark. It has earlier been reported that the proportion of participants reporting fatigue or depression is slightly different in these two localities (Avlund et al., 1994; Heikkinen, Berg, Avlund, & Törmäkangas, 2002). However, when we repeated the main regression analyses after stratifying by locality we found essentially the same results in each sample (data not shown), supporting the reliability of our results obtained from the analysis of combined data set.

When interpreting the results, some limitations and strengths of the study should be considered. This descriptive study is based on cross-sectional analyses among relatively high functioning older adults in a cohort from a single birth year from two Nordic localities. Further studies are needed to examine the generalizability of our findings to a wider age range and other populations and to clarify associations between fatigue and depression. A major strength of the study is a well-characterized cohort with standardized measures of fatigue and depression.

Footnotes

Authors’ Note

The study was approved by the local Ethical Committees and the Helsinki II declaration was observed.

Declaration of Conflicting Interests

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

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by Nordeafonden, The Danish Medical Research Council, Denmark, Academy of Finland, Ministry of Education, Ministry of Social Affairs and Health, Social Insurance Institution, and the city of Jyväskylä, Finland.

Author Biographies

Minna Mänty, PhD, is currently working as a post doc researcher at the University of Copenhagen, Department of Public Health, Denmark. Her main research interests lie in the area of early signs of mobility decline in older people.

Taina Rantanen, PhD, is a professor of gerontology and public health at the University of Jyväskylä, Department of Health Sciences, Finland. She has wide academic experience on epidemiology of aging, functional capacity in old age, and earlier life influences on aging.

Pertti Era, PhD, is a professor of gerontological rehabilitation at the University of Jyväskylä, Department of Health Sciences, Finland and a director of GeroCenter Foundation for Research and Development, Finland. He has made important academic contributions in the area of physical functioning and falls in old age.

Kirsten Avlund, PhD, is a professor of gerontology at the University of Copenhagen, Department of Public Health, Denmark. She has made significant academic contributions on the effects of social, mental and health factors for early aging, and has also contributed to drawing attention to fatigue as an early indicator of ageing.

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