Prevalence and risk factors of dementia and depressive symptoms in the elderly: A cross-sectional study in west -Greece

ACHAIKI IATRIKI | 2022; 41(3):118–125

Original Research Article

Konstantinos Argyropoulos, Christos Liatsos


Postgraduate Program “Aging and Chronic Diseases Management”, Joint degree, School of Medicine, University of Thessaly & Hellenic Open University, Greece

Received: 26 Jun 2022; Accepted: 12 Sep 2022

Corresponding author: Konstantinos Argyropoulos MD, PhD, Psychiatrist- Psychotherapist, Adjunct Academic Staff, Postgraduate Program “Aging and Chronic Diseases Management”, School of Medicine, University of Thessaly & Hellenic Open University, Greece, Tel.: +30 2103637389, E-mail: konargyropoulos@yahoo.gr, argyropoulos.konstantinos@ac.eap.gr

Key words: GDS-15, MMSE, dementia, depression, prevalence

 


Abstract

Background: The aim of the present study was to estimate the prevalence of cognitive impairment and depressive symptoms in the elderly with chronic diseases in West -Greece.

Methods: A cross-sectional study was conducted among 127 people aged 65 and over, who visited the General hospital of Krestena, Elis, West- Greece. An anonymous questionnaire was developed to collect basic demographic data. The Greek version of the Geriatric Depression Scale (GDS-15) was administered to screen the elderly for depressive symptoms and the Mini Mental State Examination (MMSE) was used to assess cognitive deficits. Statistics was processed with SPSS 24.

Results: According to the GDS-15, 27.6% (21.3% moderate and 6.3% severe type) of the studied population screened positive for depressive symptoms. 24.4% of older people were classified as presenting mild and moderate dementia, based on MMSE. Depressive symptoms were more frequent in participants without a supportive environment (p<0.001), in lower-educated (p=0.002), in single older adults (p=0.000), as well as in the elderly with no children (p=0.022) and with the presence of comorbidity(p<0.05). Cognitive impairment was strongly associated with age (p<0.001), rural place of living (p=0.007), marital status (p=0.001) and comorbidity (p<0.05).

Conclusions: Cognitive decline and depressive symptoms are common among the elderly and strongly associated with several demographic and socioeconomic risk factors.

INTRODUCTION

The rapid increase in the population of older people worldwide renders a focus on mental disorders such as depression and dementia, and aging both timely and imperative. Dementia is a syndrome characterized by difficulties in memory and other cognitive skills, affecting 1 in every 14 of the population aged 65 years or older [1]. In 2019, the number of people suffering from dementia worldwide was 50 million, whereas this number is estimated to reach 152 million in 2050 [2]. Between 2000 and 2013, deaths from prostate cancer, heart disease and stroke decreased by 11%, 14% and 23%, respectively, whereas deaths from dementia increased by 71% [2]. Dementia is a complex condition with many influencing factors and it is often difficult to pin down an exact cause. Several demographic and socioeconomic characteristics have been associated with an increased prevalence of cognitive decline including female gender, low educational level, rural place of living and the coexistence of other medical conditions such as cardiovascular comorbidity [3].

Late life depression is estimated to affect one out of seven older people above 65 years according to the World Health Organization [4]. Despite the lower overall percentage in comparison to younger counterparts, the consequences of untreated or partially treated depressive symptoms later in life results in higher mortality rates both due to suicide and medical illness [5]. The clinical features of depression observed in the elderly may be different than those seen in early ages, such as memory loss, sleeplessness, loss of appetite and somatic symptoms, mainly constipation and pain [6].

The findings of the studies performed indicate that depression in the elderly is the result of a complex multidirectional interaction of biologic (vascular depression), psychological (including personality based), and social factors. Sociodemographic parameters that have been associated with depressive symptoms later in life are the advancing of age, being a female, low educational and financial level, and the presence of comorbidities especially diseases of the cardiovascular system [7,8].

Mild cognitive impairment (MCI) is an early stage of memory loss or other cognitive ability loss (such as language or visual/spatial perception) and a systematic review in 2012 reported a prevalence of MCI ranging from 0.5 to 42% in different countries [9]. MCI is characterized as an intermediate phase between normal cognitive ageing and overt dementia and is subcategorized into Amnestic MCI that primarily affects memory and Nonamnestic MCI that affects thinking skills other than memory [9].

The purpose of the present study was to estimate the prevalence of cognitive impairment and depressive symptoms in the elderly with chronic diseases who visited the General Hospital of the rural city of Krestena of the municipality of Elis, West Greece, and to estimate possible risk factors.

MATERIALS AND METHODS

A cross-sectional study was conducted among patients over 65 years old who visited the General Hospital of Krestena, Εlis, West-Greece, Peloponnese, from January to February 2019. During the study period, the specialist physicians enrolled a total of 127 elderly, excluding patients who had been previously diagnosed either with dementia or depression.

The psychometric measure for patients’ assessment, was a structured anonymous questionnaire designed and supplied by the researchers and filled by the treating physician. The questionnaire contained items that assessed information regarding sociodemographic characteristics (age, gender, educational level, marital status, supportive environment: friends and social life), comorbid conditions (hypertension, history of myocardial infraction and stroke) and place of living (urban or rural; rural is defined as the population of those municipalities and communes in which the inhabitants of the largest population center is less than 10.000).

The evaluation of cognitive decline was made by the treating physicians on the basis of objective cognitive test. The Mini Mental State Examination (MMSE), was used to assert cognitive status of the elderly. The MMSE is a widely used 30- point screening test of cognitive function among the elderly; it includes questions of orientation, attention, memory, language, visual-spatial skills, registration, recall, calculation, language and ability to draw a complex polygon [10].

MMSE was first published in 1975 by M. F. Folstein et al, and the translation and validation in the Greek language was made by Fountoulakis et al, [10,11]. The presence of dementia is determined by the total score. Traditionally, a 23/24 cut‐off has been used to select patients with suspected dementia [12]. According to Fountoulakis et al, MMSE appeared to be valid during test and at the score level of 23/24, sensitivity is 90.80 and specificity 90.62. The severity of cognitive impairment was assessed as following: Scores 0-10 indicate severe dementia, 10-20 moderate, 21-24 mild dementia, 25-27 mild cognitive impairment (MCI) and 28-30 are considered normal [11].

Τhe Greek validated version [13] of the Geriatric Depression Scale-15 (GDS-15) was administered to all participants to screen for depressive symptoms. The GDS-15 was first developed by Yesavage et al, [14], and has been tested and used extensively in many countries to assess depression in elderly. It is a brief questionnaire, in which participants are asked to respond to 15 yes or no questions, in reference to how they felt on the day of administration. The GDS-15 has been standardized and adapted in a Greek elderly population and was found to have 92% sensitivity and 95% specificity. The severity of depressive symptoms was assessed according to Fountoulakis et al. Scores 0-5 are considered normal, 6-10 indicate moderate depression, and 11-15 indicate severe depression [13].

Informed consent explaining the objectives and procedures was obtained from all participants before the study and they were guaranteed anonymity and confidentiality. The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of the General Hospital of Krestena, Εlis, in West-Greece and every effort was made to adhere to recommended best practice principles to protect the interests and welfare of the participants.

Data was imported to IBM SPSS, for Windows v.24.0 Statistical Package (IBM Corp., Armonk, NY, USA), for analysis and interpretation. Absolute numbers (N) and percentages (N%) were used to express categorical variables, while for continuous variables descriptive analysis included mean and standard deviation.

Preliminary analyses (Q-Q plots and Kolmogorov-Smirnov) were performed to check variables for normality and outliers, ensuring the adequacy of parametric tests. Based on the results, we used t-tests and ANOVA to compare mean values of GDS and MMSE scores among the different levels of the independent variables. The Pearson’s coefficient was used to examine the correlation between GDS and MMSE scores. For all tests, statistical differences were determined to be significant at p < 0.05.

RESULTS

A total of 127 individuals participated in the study, 46% living in rural place, 49.6% were women and the mean age of all respondents was 71 years. Table 1 presents the demographic data of the studied population.

According to GDS-15, 27.6% of the participants were screened positive for depressive symptoms. 21.3% of the elderly with moderate type and 6.3% with severe.

Depressive symptoms as estimated with GDS were more frequent (Table 2) in single/ widowed than in married individuals (p=0.000), in participants without supportive environment (p<0.001), in lower-educated (p=0.002), in the elderly with no children (p=0.022) and in older people with a history of myocardial infraction (p=0.000).

MMSE results indicate that half of older participants do not suffer from cognitive impairment and scored in the normal range. Table 3 presents the prevalence of cognitive impairment and MCI among the elderly.

Cognitive decline was strongly associated (Table 4) with advancing age (p<0.001), rural compared to urban living (p=0.007), married/ widowed status in comparison to single/divorced status (p=0.001) and a history of myocardial infraction (p=0.008). Moreover, cognitive impairment was significantly associated with depressive symptoms assessed with GDS-15 (Table 5).

No significant relationship was noticed between gender and both the presence of cognitive impairment or depressive symptoms (p>0.05).

DISCUSSION

According to our results, half of the older participants did not suffer from any type of cognitive impairment whereas 4 had moderate and 27 mild dementia (total 24.4%). Epidemiological data in Greece are sparse and show major variations of prevalence depending on geographical areas. In a study conducted in different settings in the Chrisoupolis health center (HCCh) in northern Greece, 37.6% of the men and 41.6% of the women showed various degrees of cognitive impairment [15]. A recent door-to-door study among 443 participants in a rural population in Crete showed that 9.2% of individuals suffered from dementia with or without depression [16]. Another study comprised 1792 adults 65 years of age or older, with the overall prevalence of dementia reaching 5.0% [17]. Moreover, the present study supports the findings from the literature, that risk factors for cognitive impairment include older age, and modifiable factors include low physical activity, poor social life and cardiovascular health problems [3, 17]. Although lower education is associated with a greater risk for dementia in many studies, no significant association was found in the present study. According to a systematic review in 2011, the level of education which was associated with the risk for dementia varied by study population, 51 studies reported significant effects of lower education whereas 37 reported no significant relationship. The authors concluded that the risk for dementia was more consistent in developed compared to developing regions [18]. As a screening tool MMSE may overestimate or underestimate cognitive deficits depending on education and usual cognitive activities.

In the present study, the rates of cognitive impairment were higher in elderly rural residents. A number of epidemiologic studies have provided evidence regarding rural–urban differences in the prevalence of dementia and MCI [19,20]. Geographical differences and several sociodemographic factors may explain the higher prevalence of cognitive impairment observed in rural areas. A low education of rural residents as well as low levels of physical, intellectual and social activities that are recognized as risks factor for cognitive impairment may be associated with higher rates of dementia [19,20,21]. Moreover, the distance and limited access to health care providers and community services compared to those living in metropolitan areas, may contribute to the higher rates of dementia among older adults of remote regions [22,23]. Tountas and colleagues conducted a study in which rural patients were more likely to receive suboptimal healthcare because contacts with health care professionals were less frequent than those of urban residents [24]. Another study suggested that rural dementia patients may face barriers to effective ambulatory care and may experience unnecessary hospitalizations [25].

Almost one third of the elderly presented with mild cognitive impairment. MCI is a syndrome defined as cognitive decline greater than that expected for an individual’s age and education level. Prevalence in population-based epidemiological studies among the elderly is high; it ranges from 3% to 19% [26, 27]. Tsolaki et al, in Crete estimated MCI: 15.3% and MCI with depression 8.6% among the elderly [16]. Some people with MCI seems to remain stable but more than half will convert to dementia within 2 to 5 years at an accelerated rate [28].

Based on our results, depressive symptoms and cognitive impairment appear to be associated, but the relationship between the two conditions is complex and hard to determine. It remains unclear whether a history of depression is a true risk factor for dementia or rather represents a prodromal clinical phase of cognitive decline. In a recent retrospective study, 30%-50% of dementia cases were accompanied by depression [29]. A study reported depression to be a risk factor for dementia, and found that treating depression is likely to have a great impact on reducing the prevalence of dementia [230]. Depression is a treatable mental health problem, making it a potentially modifiable factor the treatment of which can prevent or delay cognitive decline [31].

In the present study 1 out of 3 of the elderly was estimated to suffer from depressive symptoms. The prevalence of depression in people over 65-year-old shows high variability depending on study design and studied population groups. Compared to the results from a previous study that we conducted in Patras and Tripolis, Peloponnese [32] in 2015 (overall prevalence 48%) the score is lower, but in line with our findings in older ages in Athens and northern Greece, with a prevalence of depression 25% and 35%, respectively [8, 33].

Previous studies have identified several stressors that serve as risk factors for late-life depressive disorders, including death of a spouse or other loved one, injuries, disability and functional decline, as well as medical illness especially diseases of the cardiovascular system [6, 32, 33]. As noted previously, the loss of a loved one is one of the most significant risk factors for late-life depression and our elder windowed and not married participants were at higher risk for developing depressive symptoms. Chronic stressors, such as lower income and education level can also influence the development of depressive symptoms later in life [34], which is confirmed in the present study. In the literature female gender has been associated with increased risk of Alzheimer’s disease [16, 17] and geriatric depression [32,33], but no statistical difference was observed among genders regarding dementia’s forms and depressive symptoms.

This is one of the few studies on elderly residents in a  rural area in Greece. It involves a real-life clinical population of patients that attend a general hospital for various health problems. While any insight into potential risk factors that might improve mental health condition of older patients and reduce the number of people affected by depressive symptoms and cognitive impairment is welcome, it’s important to recognize the limitations of this research. This is a cross-sectional study that cannot show the direction of cause and effect and no inference can be made. MMSE and GDS-15 are screening tests and their scores may be indicative but not evidential of the diagnoses of dementia /MCI or depression. Furthermore, this is not a clinical study and there were no laboratory results or neuroimaging data to analyze. Therefore, it was impossible to discriminate the type of dementia for each participant. Another limitation of the present study derives from the fact that, the prevalence of depressive symptoms and cognitive impairment depends on the cut-off scores which are used to distinguish between no depression/dementia, moderate/mild and severe form of the disorders respectively, and the validity of this threshold against the clinical diagnosis. Moreover, this sample compounds a small proportion of a specific region of West-Greece and may not be representative of the Greek population and cannot be generalized for the whole older population.

Conflict of interest disclosure

None to declare.

Declaration of funding sources

None to declare.

Author Contributions

AK contributed to study design, data analysis/interpretation and writing of the manuscript; LC contributed to study design, collection of data and data analysis/interpretation.

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