Association of Depression and Loneliness with Specific Cognitive Performance in Non-Demented Elderly Males

Abstract

Background
Loneliness and depression are very common in the aged population. Both have negative impacts on cognition in the elderly. The present study aimed to investigate the effect of loneliness and depression on total as well as specific cognitive domains in cognitively normal male subjects.

Material/Methods
A total of 189 cognitively normal male subjects were recruited and underwent Cognitive Abilities Screening Instrument (CASI) and Wechsler Digit Span Task tests. Depression was assessed by the Geriatric Depression Scale-Short Form (GDS-SF) and loneliness by UCLA loneliness scales. Partial correlation test was used to explore the correlation between loneliness/depression and total as well as specific cognition function, with the controlled factors of age and education.

Results
Both depression and loneliness are negatively correlated with global cognitive function as evaluated with CASI (r=−0.227, p=0.002; r=−0.214, p=0.003, respectively). The domains of Attention, Orientation, Abstraction and judgment, and List-generating fluency of cognitive function were specifically associated with loneliness, and the domain of orientation was associated with depression after controlling the factors age and years of education.

Conclusions
Our findings suggest that loneliness and depression may have negative impacts on global and specific domains of cognitive function in non-demented elderly males. Both loneliness and depression should be actively recognized earlier and appropriately treated because they are significant sources of cognitive impairment in the elderly.

Full text

Received: 2014.05.25
Accepted: 2014.06.16
Published: 2015.01.09
1960 1 — 33
Association of Depression and Loneliness
with Specific Cognitive Performance in Non-
Demented Elderly Males
DE 1,2,3 Ruu-Fen Tzang
CD 4,5 Albert C. Yang
B 6 Heng-Liang Yeh
D 4,5 Mu-En Liu
ABCD 4,5 Shih-Jen Tsai
Corresponding Author: Shih-Jen Tsai, e-mail: tsai610913@gmail.com
Source of support: This work was supported by grant NSC 101-2314-B-075–040 from the National Science Council, Taiwan and grants V103C-048
and VGHUST103-G1-4-1 from Taipei Veterans General Hospital, Taiwan
Background: Loneliness and depression are very common in the aged population. Both have negative impacts on cognition
in the elderly. The present study aimed to investigate the effect of loneliness and depression on total as well
as specific cognitive domains in cognitively normal male subjects.
Material/Methods: A total of 189 cognitively normal male subjects were recruited and underwent Cognitive Abilities Screening
Instrument (CASI) and Wechsler Digit Span Task tests. Depression was assessed by the Geriatric Depression
Scale-Short Form (GDS-SF) and loneliness by UCLA loneliness scales. Partial correlation test was used to ex-
plore the correlation between loneliness/depression and total as well as specific cognition function, with the
controlled factors of age and education.
Results: Both depression and loneliness are negatively correlated with global cognitive function as evaluated with CASI
(r=–0.227, p=0.002; r=–0.214, p=0.003, respectively). The domains of Attention, Orientation, Abstraction and
judgment, and List-generating fluency of cognitive function were specifically associated with loneliness, and the
domain of orientation was associated with depression after controlling the factors age and years of education.
Conclusions: Our findings suggest that loneliness and depression may have negative impacts on global and specific domains
of cognitive function in non-demented elderly males. Both loneliness and depression should be actively rec-
ognized earlier and appropriately treated because they are significant sources of cognitive impairment in the
elderly.
MeSH Keywords: Aged • Cognition • Depression • Loneliness
Full-text PDF: http://www.medscimonit.com/abstract/index/idArt/891086
Authors’ Contribution:
Study Design A
Data Collection B
Statistical Analysis C
Data Interpretation D
Manuscript Preparation E
Literature Search F
Funds Collection G
1 Department of Psychiatry, Mackay Memorial Hospital, Taipei, Taiwan
2 Department of Health Care Management, National Taipei University of Nursing
and Health Sciences, Taipei, Taiwan
3 Nursing and Management, Mackay Junior College of Medicine, Taipei, Taiwan
4 Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan
5 Division of Psychiatry, School of Medicine, National Yang-Ming University, Taipei,
Taiwan
6 Taipei Veterans Home, New-Taipei City, Taiwan
e-ISSN 1643-3750
© Med Sci Monit, 2015; 21: 100-104
DOI: 10.12659/MSM.891086
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Background
Depression is very common in elderly people, with prevalence
ranging from 1% to 16% in elderly living in private households
or institutions [1]. There is increasing evidence showing that
depression is associated with cognitive impairment and even
with dementia in later life [2]. In a study of 61 depressed sub-
jects over age 60, O’Brien et al. reported that depressed sub-
jects had multiple impairments in attention, working memo-
ry, visual memory, verbal memory, new learning, and executive
function in relation to comparison subjects [3]. In an age-strat
-
ified sample of 1982 community-dwelling individuals aged 65+
years, the number of depressive symptoms had strong, statis-
tically significant associations with performance in most cog-
nitive domains such as memory and visuospatial domains [4].
Similarly, another study found that increased depressive symp-
toms were associated with poor cognitive functioning in mul-
tiple domains [5]. In the Monongahela-Youghiogheny Healthy
Aging Team study of 2036 individuals aged 65+ years, depres-
sive symptoms remained associated with lower performance
on all cognitive composites except attention, most strongly
with executive function [4]. In a study of Chinese elderly with
late-onset depression, Tam and Lam found that the depression
group had a similar cognitive profile to those with mild cogni-
tive impairment, except that its subjects had slightly better per-
formance in the Categorical Verbal Fluency Test and delayed
recall testing [6]. In a companion report, they showed that in-
creasingly severe depression was associated with lower scores
in the Mini-Mental State Examination and delayed recall, and
poorer performance in the Trail Making Test-Part A [7]. A strong
association between depression and decreased cognition was
found in 2 studies: Rosenberg et al. observed scores on 6 ex-
aminations during a 9-year period and reported that higher
Geriatric Depression scale (GDS) baseline score was highly re-
lated to cognitive decline by [8], and a study of 501 women age
70–74 years showed depression co-occurred with worse cogni-
tive performance [9], but the cognitive performance did not de-
cline in individuals with previous depression, suggesting that
cognitive dysfunction is a state phenomenon in depression [9].
In addition to depression, loneliness is also commonly found in
elderly people; this emotionally unpleasant experience is a cru-
cial marker of social relationship deficits. Holmén et al. studied
elderly people from rural areas in Sweden and showed that 35%
of them reported they experienced loneliness (by asking the
simple question: “Do you experience loneliness?”) [10]. A study
in Israel, based on home interviews of 70-year-olds, showed
that 46.3% of females and 21.3% of males reported being lone
-
ly [11]. While loneliness can be a normative experience, it also
has the potential to be pathological, with adverse health con-
sequences and cognitive effects in older people [12,13]. In an
elderly population, it was found that feeling lonely is a predic-
tor of significant cognitive decline [14]. In 2007, Wilson et al.
examined the risk of developing Alzheimer’s disease (AD) in
a cohort of older adults over a 4-year period and found that
the risk of developing AD was substantially increased in those
who were lonely compared to those who were not lonely, even
when controlling for the level of social activities [15].
Despite the apparent effects of loneliness on global cognitive
function in the normal elderly, there are few studies exploring
their effects on specific cognitive function. In a cross-sectional
study of 466 elderly community-dwelling subjects, it was found
that loneliness was significantly associated with impaired global
cognition, independent of social networks and depression [16].
The cognitive domains of psychomotor processing speed and
delayed visual memory were particularly associated with self-re-
ported loneliness [16]. The study was done in a Western popu-
lation and loneliness was ascertained using the single question
“How often do you feel lonely?”, with participants selecting 1 of
the following responses: never, rarely, sometimes, or often. The
aim of this study was to investigate the impact of depression and
loneliness on objective performance on tests of several cognitive
domains in older Chinese subjects without dementia. The loneli-
ness was assessed by the Loneliness Scale. To minimize the con-
founding effects of gender [17,18], a homogenous group was con-
structed, composed entirely of healthy aged Han Chinese males.
Material and Methods
Participants and data collection
This study included a total of 189 participants recruited from
a Veteran’s Home in Taiwan, as reported in our previous study
[19]. A trained research nurse checked initial evaluation data,
including self-reported current and past medical status, as well
as medical records of each participant. A board-certified psy-
chiatrist evaluated every participant’s neurological state and
psychiatric diagnosis by structured interviewing with the Mini-
International Neuropsychiatric Interview (MINI) [20]. Daily ac-
tivities and cognitive functions were assessed by using the
Clinical Dementia Rating scale (CDR).
These criteria for recruiting a group of non-demented elderly
subjects with normal daily activities included sufficient visual
and auditory acuity for cognitive testing. Therefore, exclusion
criteria included the following: (1) presence of diagnoses on
Axis I of the DSM-IV; (2) chronic medical illness under medi-
cal control (e.g., malignancy, heart failure, lung disease, diabe-
tes); (3) neurobiological disorders (e.g., stroke or Parkinson’s
disease); (4) subjects with CDR >0.5 or Mini-Mental Status
Examination (MMSE) <24 to exclude possible dementia. The
cut-off point of 24/30 in MMSE was chosen because of world-
wide usage and as the best compromise between sensitivity
and specificity for screening for dementia [21].
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This study was conducted in accordance with the Declaration
of Helsinki and was approved by the Institutional Review Board
of Taipei Veterans General Hospital. Informed consent was ob-
tained from all subjects prior to commencement.
Measurement
Cognitive ability
All participants were administered the Cognitive Abilities
Screening Instrument Chinese version (CA2.SI C-2.0) test [22]
and the Wechsler Digit Span Task test. These cognitive tests
were conducted by a trained research nurse. The CASI C-2.0
test, a 100-point cognitive test designed for cross-cultural
studies and adapted in Chinese for individuals with little or
no formal education [23], also provided quantitative assess-
ment in 9 domains of cognitive function (long-term memory,
short-term memory, attention, concentration/mental manip-
ulation, orientation, abstraction and judgement, language, vi-
sual construction, and list-generating fluency).
The Wechsler Digit Span Task test requires the examiner to
verbally present digits at a rate of 1 digit per second. The for-
ward test requires the participant to repeat the digits verba-
tim; the backward test requires the participant to repeat the
digits in reverse order. The number of digits increases by 1 un-
til the participant consecutively fails 2 trials of the same dig-
it span length. Forward and backward digit span recall abili-
ties have been widely used to assess short-term memory and
working memory, respectively, in neuropsychological research
and clinical evaluation [24].
Depression
Depression was assessed by the Chinese version of the Geriatric
Depression Scale-short form (GDS-SF) [25]. Scores on the
GDS-SF showed a high validity in accordance with the origi-
nal version [26].
Loneliness
We use the Loneliness Scale (University of California, Los
Angeles, UCLA version 3) [27] to assess loneliness. The UCLA
Loneliness Scale contains 20 items. The participants used a
4-point Likert scale (ranging from ‘never’ to ‘often’) to assess
how often they felt the way described in the loneliness items.
Statistical analyses
Partial correlations were calculated to estimate the indepen-
dent associations between the depression/loneliness and cog-
nitive parameters. GDS-S scores of depression and the cog-
nitive parameters of cognitive function were used to explore
their partial correlations after controlling for their mutual as-
sociation with age and education years. For the partial cor-
relations between loneliness and the cognitive functions, we
also controlled the depression score in terms of age and ed-
ucation. To minimize chance occurrence of significant statis-
tical difference with multiple comparisons (12 comparisons),
Bonferroni correction was applied to find the appropriate lev-
el of p value for statistical significance. The p value for signifi-
cant statistical difference for each test was lowered to 0.0042
to bring the p value overall back to 0.05 for multiple compar-
isons performed in the present study. All statistical analyses
were conducted using SPSS v15.0 (SPSS Inc., Chicago, IL, USA).
Data are presented as means (SD).
Results
The subjects were 189 males, ages 65–98 years (mean=80.2;
SD=4.5), with an average of 5.2 years of education (SD=4.2;
range, 0–16 years of schooling). Cognitive function tests showed
that the mean CASI score was 85.9±10.4 (range, 57–100).
Partial correlations between depression, loneliness, and to-
tal/specific cognitive parameters are presented in Table 1. Both
depression and loneliness are negatively correlated with glob-
al cognitive function as evaluated with CASI C-2.0 (r=–0.227,
p=0.002; r=–0.214, p=0.003, respectively). Further analysis of
the 9 domains of CASI scores demonstrated that depression
is specifically negatively correlated with Orientation. For lone-
liness, it is negatively correlated with Attention, Orientation,
Abstraction and judgment, and List-generating fluency (Table 1).
Discussion
The principle finding of this study is that, in our sample of
elderly Chinese males, loneliness correlated negatively with
global cognitive function (Total CASI) after controlling age,
education, and depression scores (Table 1). Further analysis
demonstrated that loneliness correlated negatively specifi-
cally with Attention, Orientation, Abstraction and judgment,
and List-generating fluency. These results replicate previous
studies reporting that loneliness is negatively correlated with
cognitive function [14,15], and extended prior findings that
loneliness has impacts on specific cognitive domains [16]. A
previous study of loneliness and specific cognitive functions
showed that cognitive domains of psychomotor processing
speed and delayed visual memory were particularly associat-
ed with self-reported loneliness [16]. The difference in findings
between this study and our study could be due to differences
in cognitive evaluation (cognitive test battery vs. CASI), lone-
liness evaluation (single question vs. UCLA Loneliness Scale),
ethnicity (Irish vs. Chinese) and gender (both genders vs. male
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Depression, loneliness, and cognition
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gender). The mechanisms of the associations between specif-
ic cognitive functions and loneliness were unclear and war-
rant further investigation.
In this study we also found that depression is negatively cor-
related with global cognition, which is in line with the findings
in earlier studies [2,8,9]. In further analysis of the correlations
with specific CASI domains, the strongest correlation was with
the Orientation domain. Previous studies of older patients with
depressive disorders suggest a consistent pattern of association
with diminished processing speed and executive function [28–30].
Our results extend those of previous findings and suggest that
depression may also affect Orientation cognitive domains.
A previous study of loneliness and depression in the elder-
ly showed that the 2 strongly co-occur with each other [31],
although another report suggested that both appear to be
distinct phenomena [32]. Intense loneliness might result in
diminished feelings of self-worth and lack of confidence in in-
terpersonal relationships, thus leading to depression. In this
study, after adjusting for depressive severity, the loneliness
rating remained correlated with lower performance on glob-
al cognitive function and has more correlation with compos-
ites than depression (4 items vs. 1 item). Our study demon-
strates that the impact of loneliness on cognitive function is
independent of depression and may have more effects than
depression on specific cognitive domains. Interventions to al-
leviate loneliness in the elderly, such as interventions address-
ing maladaptive social cognition, may be particularly benefi-
cial to prevent cognitive impairment [33].
The strengths of the study include use of a rather homoge-
nous population-based sample and availability of multiple cog-
nitive parameters. Limitations include that this study had a
cross-sectional design. A prospective study would better ad-
dress the causal relation between cognitive function and ge-
riatric depressive symptoms and loneliness. An additional lim-
itation is that our sample represents elderly male veterans
living in veteran housing, and the findings of the association
between the specific cognitive functions and depression/lone
-
liness may need to be further validated in younger adults, fe-
males, or other populations.
Conclusions
Our findings suggest that loneliness and depression are nega-
tively correlated with global as well as specific cognitive func-
tion in cognitively normal elderly males. Both loneliness and
depression should be actively recognized and appropriately
treated because they are significant sources of cognitive im-
pairment in the elderly.
Acknowledgments
The authors would like to thank Dr. D.W. Russell for agree-
ing to allow the use of the UCLA Loneliness Scale (Version 3).
Conflict of interest
None declared.
GDS-SF UCLA loneliness
scales
CASI
Long-term memory –0.151 (0.040) –0.154 (0.036)
Short-term memory –0.054 (0.463) –0.141 (0.054)
Attention –0.156 (0.033) –0.215 (0.003)
Concentration/mental
manipulation –0.168 (0.021) –0.103 (0.161)
Orientation –0.259 (<0.001) –0.209 (0.004)
Abstraction and
judgement –0.095 (0.194) –0.218 (0.003)
Language –0.088 (0.233) –0.070 (0.346)
Visual construction –0.064 (0.383) –0.104 (0.157)
List-generating fluency –0.082 (0.266) –0.204 (0.005)
Total CASI –0.227 (0.002) –0.214 (0.003)
Wechsler Digit Span Task
Forward –0.062 (0.400) –0.125 (0.089)
Backward –0.046 (0.534) –0.133 (0.070)
Table 1. Partial correlations between depression/loneliness
and total/specific cognitive functions. Data represent
correlation coefficient r (p value).
GDS-SF – Geriatric Depression Scale-Short Form. Partial
correlations between depression/loneliness and specific
cognitive functions were performed after controlling for age
and education years. For partial correlations between loneliness
and specific cognitive functions, depression scores were also
controlled. Boldface indicates a p-value lower than 0.0042.
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