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| ORIGINAL ARTICLE |
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| Year : 2021 | Volume
: 8
| Issue : 2 | Page : 107-112 |
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A study of quality of sleep, quality of life, and cognition in elderly: Healthy control, depressed and with mild neurocognitive disorder
Samiksha Jadhav1, Alka Anand Subramanyam2, Nitin B Raut3, Shipra Singh4
1 Department of Psychiatry, Civil Hospital, Ratnagiri, Maharashtra, India
2 Department of Psychiatry, B.Y.L. Nair Hospital and T.N.M.C, Mumbai, Maharashtra, India
3 Department of Psychiatry, Lady Hardinge Medical College, New Delhi, India
4 Department of Psychiatry, Institute of Mental Health, PGIMS, Rohtak, Haryana, India
| Date of Submission | 01-Sep-2021 |
| Date of Decision | 07-Oct-2021 |
| Date of Acceptance | 23-Oct-2021 |
| Date of Web Publication | 31-Jan-2022 |
Correspondence Address:
Dr. Shipra Singh
Department of Psychiatry, Institute of Mental Health, PGIMS, Rohtak, Haryana
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jgmh.jgmh_35_21
Background: Sleep plays a vital role in maintaining optimum physical and mental functioning and can be implicated in affecting the quality of life (QOL) and cognition in elderly population. This study aims to assess quality of sleep, QOL and to assess the effect of quality of sleep on QOL and cognition in elderly population Materials and Methods: A cross-sectional study was done in elderly population in which 30 were healthy control, 30 depressed, and 30 with mild neurocognitive disorder (NCD) who were assessed using Pittsburg Sleep Quality Index, World Health Organization QOL (WHOQOL)-BREF, Geriatric Depression Scale-Short form, and Addenbrooke's Cognitive Examination Scale-Revised (ACE-R). Statistical analysis was done using SPSS 20 software using descriptive methods and Pearson's correlation test. Results: Mean Pittsburgh Sleep Quality Index (PSQI) score was the lowest and mean WHOQOL-BREF score highest in healthy control compared to elderly with mild NCD and depression, the difference being statistically significant in both cases (P < 0.01). PSQI scores have negative correlation with the ACE-R scores when studied in healthy control group (P < 0.05, r = −0.136) and WHOQOL-BREF domain scores overall (P < 0.01 r = −0.485, −0.497, −0.350, −0.475). Conclusion: Quality of sleep in elderly with depression and mild NCD is lower as compared to healthy control. Sleep may affect QOL and cognition in elderly and thus it would be essential to screen and identify sleep-related issues and intervene early.
Keywords: Cognition, depression, elderly, mild neurocognitive disorder, quality of life, sleep
How to cite this article:
Jadhav S, Subramanyam AA, Raut NB, Singh S. A study of quality of sleep, quality of life, and cognition in elderly: Healthy control, depressed and with mild neurocognitive disorder. J Geriatr Ment Health 2021;8:107-12 |
How to cite this URL:
Jadhav S, Subramanyam AA, Raut NB, Singh S. A study of quality of sleep, quality of life, and cognition in elderly: Healthy control, depressed and with mild neurocognitive disorder. J Geriatr Ment Health [serial online] 2021 [cited 2023 Jun 7];8:107-12. Available from: https://www.jgmh.org/text.asp?2021/8/2/107/336908 |
| Introduction | |  |
Elderly population has become a rapidly growing segment of population worldwide. According to the United Nations Population Fund document, 2017, global population above 60 years of age constitutes about 11% of the total population, which is expected to become 22% by about 2050. Similar trend is observed in India as well, which is likely to continue in coming decades. Number of people aged 60 and above is projected to increase from 8% in 2015 to 19% in 2050.[1]
With rapid increase in elderly population, late life physical and mental health problems are increasing simultaneously. Many of the physical and mental conditions are due to deteriorating physiological reserves and impaired immune system in elderly population.[2] More than 20% of older adults have a mental or neurological disorder, accounting for around 6.6% of all disability (disability-adjusted life years) among people more than 60 years of age. Dementia and depression are the two most common disorders, affecting 5% and 7% of population in this age group, respectively.[3] However, number and rate of increase appear to be much larger in developing countries.[4] Recently, closer attention is also paid on symptoms such as sleep disturbances, decreased appetite, and multiple somatic complaints in elderly population, which along with mental illnesses or mental health issues have been found to affect quality of life (QOL) adversely.[5] QOL, a term widely used in clinical studies, is defined by the World Health Organization (WHO), as an individual's perception of their position in life in context of culture and value systems in which they live and in relation to their goals, expectations, standards, and concerns.[6] Insomnia and other sleep problems are found to have negative effects on health and QOL. Several population-based studies have demonstrated association between impaired sleep and worse performance on global measures and specific individual domains of QOL in elderly.[7]
Sleep is one of the vital components for maintaining optimum physical and mental functioning. Lack of sleep can be associated with day time fatigue, impaired cognitive functioning, mood disturbances, increased rates of infections, depression, impaired productivity at work place, and a delirious effect on all body systems. This indicates that sleep disorders have negative consequences for health, functioning, and overall QOL.[8]
Sleep pattern changes with age and certain parameters are found to be associated with increased risk for cognitive impairment or dementia.[9] Cognitive disturbance is other common complaint seen in elderly population. Clinically, it is reflected in impaired functioning, forgetfulness, repetitiveness, difficulty in carrying out tasks that would be routine in the past, getting lost in familiar places or becoming disoriented. Mild cognitive impairment represents an intermediate state of cognitive function between the changes seen in aging and those fulfilling the criteria for dementia and often Alzheimer's disease.[10] Cognitive disturbance can have a profound impact on one's ability to function on a daily basis. Studies are available that demonstrate a negative effect of sleep on cognitive functioning and it seems clear that perceived poor sleep quality, sleep deprivation, napping, and sleep disorders are related to cognitive dysfunction in elderly population.[11]
Depression is another common psychiatric disorder in elderly population. As we know, cognitive functioning gradually decreases with normal aging. Depression in elderly can itself be associated with cognitive impairment. Numerous studies have also demonstrated the presence of cognitive deficits in elderly population with depression, which can be attributed to reduced motivation, attenuated attention capacity, impaired concentration, intrusive thoughts, and slowness. Further, late-life depression has been identified as an independent risk factor for developing dementia.[12]
There are indicators that sleep has a bearing on QOL and also cognitive functioning. Quality of sleep affects QOL and cognition in elderly population. In elderly population, quality of sleep and QOL are interrelated. This study was planned with the hypothesis that, this relationship varies in healthy control, depressed, and elderly population with mild neurocognitive impairment. Furthermore, in elderly population, QOL and neurocognitive impairment considerably affect quality of sleep.
| Materials and Methods | | |
It was a cross-sectional study carried out in the psychogeriatric clinic of psychiatry OPD of a tertiary care teaching municipal institute in Mumbai after obtaining requisite approval by the Institutional Ethics Committee. This study enrolled a total of 90 elderly participants, who were of age 60 years or more, under three groups with 30 participants per group. The groups were (1) those having major depressive disorder (MDD), as per DSM-5 criteria, with a minimum duration of illness of 3 months; (2) those with mild neurocognitive disorder (mild NCD), as per DSM-5 criteria; (3) healthy age-matched controls, those who did not have any psychiatric illness or cognitive impairment based on clinical assessment. Participants with uncontrolled medical or surgical illness, mental retardation, and head injury were excluded. Furthermore, participants with MDD and mild NCD, if had any other comorbid psychiatric illness, were also excluded. A written informed consent was taken from the participants before commencing the study. Following tools were used for assessment and capturing the details:
- Semi-structured pro forma: It was used to collect the sociodemographic details of the participants
- WHOQOL-BREF Scale: This instrument comprises 26 items, which measure the following domains: physical health, psychological health, social relationships, and environment. The WHOQOL original version includes 236 items, which after field-testing, was reduced to 100 items in the final version, the WHOQOL-100. For use in clinical trials, the WHOQOL group has developed an abbreviated version of WHOQOL-100, the WHOQOL-BREF, which contains 26 items.[13] WHOQOL-BREF has shown good to excellent psychometric properties of reliability and performs well in tests of validity, and is a sound, cross-culturally valid assessment of QOL[14]
- Pittsburgh Sleep Quality Scale (PSQI): It is an effective instrument used to measure the quality and patterns of sleep. It differentiates “poor” and “good” sleep by measuring seven domains: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction over the past month. Scoring of the answers is based on a 0–3 scale, whereby 3 reflect the negative extreme of the Likert scale. The PSQI has internal consistency and a reliability coefficient (Cronbach's alpha) of 0.83 for its seven components.[15] The Hindi adaptation of PSQI was used in the study[16]
- Geriatric Depression Scale (GDS): It was first created by Yesavage et al. and has been tested and used extensively with the older population to measure depression. The GDS Long Form is a brief, 30-item questionnaire in which participants are asked to respond by answering yes or no in reference to how they felt over the past week. A Short Form GDS consisting of 15 questions was developed in 1986. Of the 15 items, 10 indicated the presence of depression when answered positively, while the rest (question numbers 1, 5, 7, 11, 13) indicated depression when answered negatively. The GDS was found to have 92% sensitivity and 89% specificity when evaluated against diagnostic criteria. Its validity and reliability have been supported through both clinical practice and research[17],[18]
- Addenbrooke's Cognitive Examination Revised (ACE-R): It is a brief “bedside” cognitive screening instrument, helps in evaluating six cognitive domains – orientation, attention, memory, verbal fluency, language, and visuospatial ability. It is also effective for differentiating the subtypes of dementia, such as Alzheimer's disease, frontotemporal dementia, progressive supranuclear palsy, and other forms of dementia associated with Parkinsonism More Details. The alpha coefficient of the ACE-R is 0.80.[19] The scale has been normed with significant validity and reliability for the Indian population by Mathuranath et al. The normative data was gathered specifically from south India; however, the authors have reported that the normative data can be generalized and used for the rest of India.[20],[21]
Statistical analysis
SPSS version 20 (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp.) was used to statistically analyze the data obtained. Descriptive methods were used to describe the study variables. The relation between the variables was assessed using Pearson's correlation among the three groups; the comparison of quality of sleep and cognition in the three groups was performed using one-way ANOVA with post hoc test.
| Results | | |
Among the study participants, 53.3% were female and rest male. Majority (53.3%) were in the age group of 60–65 years, 38.9% were 65–70 years, and rest belong to 70–75-year age group. Most of them (91.1%) were educated.
The mean score of GDS in healthy control was 1.13 (SD = 1.45), in depression group was 7.23 (SD = 1.76), and in mild NCD was 2.16 (SD = 1.52). Mainly three factors were studied in elderly population, i.e., quality of sleep, QOL, and cognition in the three groups, i.e., healthy control, depressed and with mild NCD. Results suggest that mean PSQI score was the lowest in healthy control (6.53), when compared to elderly with mild NCD (9.57) and depression (14.27) and this difference was found to be statistically significant (P < 0.001) on one-way ANOVA [Table 1]. Further, the difference on PSQI scores between individual groups compared to the other two groups was also found significant in each case (dF = 2, F = 42.946, P < 0.001), which was established by post hoc multiple comparisons with Bonferroni correction (healthy control > mild NCD > depression). | Table 1: Mean scores of Pittsburgh Sleep Quality Scale in the three study groups
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On comparing, the mean scores of individual domains of WHOQOL-BREF results suggest that the mean scores of all domains are higher in healthy control elderly population as compared to elderly with depression and mild NCD. Furthermore, the difference between the three groups was statistically significant on individual domains as well as cumulative scores (P < 0.001) [Table 2]. On post hoc test with Bonferroni correction, each domain score of quality scale was significantly different from the other two groups (P < 0.01) (healthy control >mild NCD >depression for all domains as well as cumulative score) [Table 3]. Mean cumulative and individual domain scores of ACE-R are shown in [Table 4]. | Table 2: Comparison of cumulative and individual domain scores of quality of life (World Health Organization quality of life BREF) in the three groups (using ANOVA)
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 | Table 3: Post hoc analysis of quality of life (World Health Organization quality of life BREF) in the three groups
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 | Table 4: Mean cumulative and subscale scores of Addenbrooke's cognitive examination revised in the group of healthy control and depression
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On studying the relationship of sleep quality with QOL and cognitive functioning separately in the three study groups, no significant correlation could be observed [Table 5]. However, on studying the relation of quality of sleep with QOL in the entire sample, it was observed that PSQI scores had significant relationship with all the four domains of QOL, with a negative correlation between PSQI scores and QOL scores, which suggests that as quality of sleep increases, so does the QOL (as higher PSQI scores refer to poor sleep quality) [Table 6]. | Table 5: Correlation of sleep quality (Pittsburgh Sleep Quality Scale scores) with quality of life and cognition in the three study groups
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 | Table 6: Correlation of sleep quality (Pittsburgh Sleep Quality Scale scores) with quality of life scores among all the participants
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In addition, [Table 5] shows that correlation of sleep quality and cognition was significant in healthy control group (P = 0.047, correlation coefficient = −0.136) (negative correlation between PSQI score and ACE-R score) but not in MDD or mild NCD group. When relationship with subscales of ACE was explored, it was observed that visuospatial component of cognition significantly correlated with sleep quality.
| Discussion | | |
Sleep is an essential biological function and is considered vital for overall health of an individual. Sleep quality changes as a function of normal aging, both in terms of decreased duration and consolidation.[22] Recent findings suggest that sleep quality plays a critical role in preserving mental health and cognitive function in older adults.[23] Unfortunately, sleep complaints are very common among older adults and given the world's aging population, it is an important area to be looked in depth. In this study, quality of sleep is assessed in three groups of elderly, those without comorbid mental or pain condition, those having depression and in those having mild NCD; along with its relation with QOL and cognitive functioning.
The results of this study showed the quality of sleep was better in healthy control group as compared mild NCD, which was better compared to MDD group. The earlier studies and meta-analysis have shown that lack of good quality sleep is significantly related to depression in older adults.[24],[25] Similarly, sleep quality is found to be affected in those with cognitive disturbances, including both mild neurocognitive impairment and dementia, which is consistent with earlier research.[9],[26],[27],[28]
Our study also found that the QOL also differed in the three groups. There is decline in well-being in elderly, in general, due to various reasons such as declining health, loss of loved ones, or shifting locus of control. In this study, QOL in healthy control group significantly differed, i.e., significantly higher from the groups of MDD and mild NCD. According to the review by Sivertsen et al., people with depression, either at symptom or disorder level, have been found to have poorer QOL, and this association was observed to be stable over time. Severity of depression is directly involved in determining the QOL. Depression actually is a common comorbidity in elderly persons with physical health difficulties.[29] Minor NCD, by definition, is the acknowledgment of the cognitive deficits by the individual, yet these deficits not interfering with capacity for independence in everyday activities.[30] However, research has shown that the QOL in persons with MILD NCD or MCI is lower. When matched with the controls, Hussenoeder et al. found that people with MCI have lower QOL, which included the domains of autonomy; past, present, and future activities; social participation; and intimacy.[31] There is limited data comparing QOL between elderly with depression and those with mild NCD; however, connecting the two conditions, there are studies which have found that depression is very common in MCI and could be a possible risk factor for the cognitive decline and its progression.[32]
On assessing the relationship of sleep quality with QOL in different study groups, no significant difference was found. However, on studying the relation of sleep with QOL in the entire study sample, it was statistically significant with each domain of QOL. Sleep is known to have effect on optimum functioning of body and mind and boosts up one's immunity. Prolonged sleep difficulties are related increased risk of heart diseases, diabetes, and other metabolic conditions.[33] According to Zhao et al., sleep quality was directly related to physical and mental health.[34] The possible explanation that they provided for this is that better sleep in elderly helps them feel fresh and provides them the energy to participate in regular physical activity, which would thereby improve their physical health. Regular physical activity, on the other hand, prevents various chronic illnesses, as discussed earlier.[35] In relation to psychological health, research investigating the link between sleep and mood revealed that a bidirectional relationship exists between the two, i.e., an individual's mood (both positive and negative) can affect the sleep quality and vice-versa.[36] Hanson and Ruthig mention that even after controlling for other contributory factors in the psychological well-being such as age, gender, physical health, functional status, income, level of stress and amount of physical activity, sleep quality accounted for multiple aspects of psychological well-being of elderly.[37] In relation to the third domain of the WHOQOL-BREF, i.e., social relationships, earlier research has shown that sleep quality was related to supportive social ties and worse sleep quality related to aversive ties; the two parameters sharing a bidirectional relationship.[38] Further, the environmental health which to certain extent links to one's self efficacy might also get affected by sleep. Such relations have been found with depression in elderly and even other age groups as well.[7],[39] Song et al. found that poor sleep quality was related to health-related QOL in individuals with MCI.[40]
This study also found significant correlation between sleep quality and cognition in the healthy control group. However, this relation could not be observed in the other two groups. On studying the individual domains of the assessment tool ACE-R, this relation was in the visuospatial domain. Sleep plays an important role in consolidation of different types of memory and inferential thinking.[41] Other researchers have described that specific aspects of sleep and presence of sleep disorders are associated with the risk of dementia and can also affect dementia prognosis.[9] A recent meta-analysis reports that sleep disturbances or sleep disorders are linked to higher risk of all-cause cognitive disorders.[42] Although memory is the most important element of cognition that has been studied in relation to sleep, the studies do mention the mediating effect of sleep on cognition, leading to disruption in everyday functioning in elderly, including activities of daily living, instrumental activities of daily living, which require appropriate visuospatial abilities of the individual.[43] The Bronx aging study also mentions that after controlling for depression, use of hypnotic medication, physical morbidity, age, and education, sleep-related issues was significantly related to poor performance on verbal knowledge, memory, and visuospatial domain.[44] However, there are studies which have equivocal findings as well. A review of multidisciplinary research concluded that sleep promotes memory consolidation, sleep deprivation can causes cognitive impairments in young adults more than in older adults and finally that inter- and intra-variability in sleep in older adults often do not relate to cognitive functioning and solely improving sleep may not be adequate to reverse cognitive impairments.[45]
This study has limitation of being cross-sectional and having a small sample size; therefore, results might not be generalizable. The ongoing medication of the participants with comorbid physical illness (even though controlled) was not studied, which could be a contributing factor to sleep disturbance. PSQI, being a self-rated measure, can create certain level of subjective bias, mainly in depression and mild NCD group participants.
| Conclusion | | |
Sleep is an essential element that can affect the physical, psychological, and social well-being of elderly. It has implications on an individual's cognitive functioning as well. Sleep issues are extremely common in elderly and can often go unrecognized or overlooked, which can subsequently lead to multiple physical and mental issues. According to our findings, sleep quality is poor in elderly with depression and mild NCD as compared to healthy controls; further sleep quality was found to affect cognition, specifically its viusuospatial component. Based on Rowe and Kahn's model of successful aging,[46] which includes maximization of cognitive and physical functioning, active engagement in life, and prevention of disease and disability, the importance of sleep is well evident for its attainment. In spite of the limitations of our study, about the role of other factors affecting cognition, it seems imperative that screening for disturbances in sleep should be done in all elderly, irrespective of their presenting complaints; sleep hygiene should be promoted and early intervention for sleep-related issues should be done in appropriate cases.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]
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