INTRODUCTION

According to the World Health Organization (WHO), currently the number of people aged 60 years or more exceeds that of children under five years of age; additionally, between 2020 and 2030, the percentage of older people will increase by 34 %, following this pattern, by 2050 the number of older people will exceed that of adolescents and young people between 15 and 24 years of age ¹, this phenomenon is known as population ageing.

The above is especially relevant when problems associated with aging, such as loneliness, have been reported ², which has a negative relationship with the health of older people, with poorer cognitive function, worsening of memory and verbal fluency³. Moreover, this impact on cognitive functioning can exacerbate loneliness, generating a vicious circle that generates an even worse outcome in such population⁴.

Based on the above, considering that physiologically the body loses functions over the years, which make older people more vulnerable, there are risk factors that can aggravate loneliness, as in the case of the current COVID-19 pandemic, which has been associated with an increase in loneliness ⁵, and this, in turn, has been strongly related to the presence of anxiety and depression. Therefore, given the demographic change that the world is experiencing, added to the increase in loneliness in the elderly and its association with health problems, it is important to know what has been described in this regard.

OBJECTIVE

Under the above premise, the following question arises: What diseases are associated with loneliness in the elderly? In order to answer this question, an integrative review was considered to know the state of the art, responding to the objective of identifying the pathologies associated with loneliness in the elderly.

METHODS

Secondary research, of the integrative review type, structured, according to Crossetti⁶, which is comprised by five stages: 1. Problem formulation, 2. Data collection or definitions on literature search, 3. Data evaluation, 4. Data analysis, and finally 5. Presentation of results and interpretation.

To comply with the first stage, the following question was formulated: What diseases are associated with loneliness in the elderly? In the second stage, the different searches were organized in Spanish, English and Portuguese, using the descriptors validated in the DeCS thesaurus and Booleans described in Table No. 1.

Table No. 1. Descriptors and Booleans used in search process. 

Source: Self-development, 2022.

The databases used were WoS (Web of Science), PubMed (United States National Library of Medicine), SciELO (Scientific Electronic Library Online) and BVS (Biblioteca Virtual de Salud). Table N°2 shows the search strategies and filters used in each database.

Table No. 2. Search strategies and filters applied. 

Source: Self-development, 2022.

The inclusion criteria used was composed by articles in the three languages mentioned, published in the period ranging from 2016 to 2021 (until June), and that related loneliness as an independent variable and pathologies in the elderly as dependent variables; the exclusion criteria corresponded to articles that do not have free access, duplicates and letters to the editor. Figure N°1 shows the review flowchart.

Figure No. 1. State of the art review flowchart. 

After applying descriptors and search strategies, a total of 4,011 articles were identified, 852 located in the WoS database, 7 in SciELO, 2,101 in BVS and 1,051 in PubMed; after applying the filters, 818 articles remained, of which 167 corresponded to WoS, 1 to SciELO, 376 to BVS and 274 to PubMed. Then, after applying the inclusion criteria, 60 articles remained, 18 corresponding to WoS, 23 to BVS and 1 to PubMed, and finally, after applying the exclusion criteria, 27 articles were selected ^{2)(3)(4)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30}, of which 17 corresponded to WoS ^{2)(4)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21}, 9 to BVS ^{3)(22)(23)(24)(25)(26)(27)(28)(29} and 1 to PubMed ³⁰, thus fulfilling stage 3 and 4 of Crossetti.

RESULTS

In compliance with Crossetti’s stage 5 “results presentation and interpretation” the most relevant results of the integrative review are summarized in Table N°3 according to article name, authors, country, year, objective and main results.

Table No. 3. Main results of relationship between loneliness in the elderly and associated pathologies in selected articles. 

Table No. 3 (cont.). Main results of relationship between loneliness in the elderly and associated pathologies in selected articles. 

Table No. 3 (cont.). Main results of relationship between loneliness in the elderly and associated pathologies in selected articles. 

Table No. 3 (cont.). Main results of relationship between loneliness in the elderly and associated pathologies in selected articles. 

Table No. 3 (cont.). Main results of relationship between loneliness in the elderly and associated pathologies in selected articles. 

Table No. 3 (cont.). Main results of relationship between loneliness in the elderly and associated pathologies in selected articles. 

Source: Self-development, 2022.

DISCUSSION

Currently there is a large amount of research on the subject ^{2)(3)(4)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30}, recognizing that it is a subject that is being highly researched, demonstrating the efforts to clarify the associations between loneliness and morbidities in the elderly.

The majority of results found a relationship between loneliness and pathologies in the elderly (24 of 27 studies). Associations found between loneliness and death were very diverse, on the one hand, some authors stated that loneliness increases the risk of death ^18,27, while others report that there is no such relationship ^2,11, likewise, others describe a relationship when there is loneliness concomitantly with frailty ¹⁷.

Loneliness as a cause of cognitive impairment was present in all the studies that analyzed it ^{3)(4)(9)(13)(14)(21)(23}, both independently ^{3)(4)(14)(21)(23}, as with association with depressive symptoms ^9,13; an important aspect is the description of a “vicious circle”, product of the exacerbation of loneliness due to cognitive dysfunction ⁴.

Another association identified with loneliness was the physical state of the older adult; in some studies they identified poorer physical health ¹⁰, risk of becoming physically frailer ²⁵, poorer physical performance ²⁹, or risk of fatigue and physical inactivity ²¹.

An interesting aspect to highlight is that in the selected studies that described a relationship associated with one gender, all were linked to women, for example: one article associated loneliness with lower grip strength only in women ²⁰, other authors demonstrated that loneliness is a predictor of cardiovascular mortality in women ³⁰, and another article described a relationship between loneliness and cardiovascular diseases only in women ¹²; however, in this last study the authors reported that said relationship can be explained by depression, which indicated that loneliness in its own right does not seem to be related to cardiovascular disease, although this is subject to discussion, since in another research loneliness was associated with an increased risk of developing depressive symptoms ⁷.

Loneliness was also associated with the risk of developing dementia, one study pointed out its relationship with all-cause dementia and Alzheimer's disease ¹⁶, another with preclinical Alzheimer's disease ²⁴, and finally, an article associated it with multi-morbidities such as Alzheimer's disease, psychiatric diseases, immune dysfunction and cancer ²².

Regarding the relationship between loneliness and cardiovascular events, one study showed a significant correlation with higher blood pressure ²⁸; additionally, another study related it to a higher risk of developing coronary heart disease and stroke ³⁰. However, another article reported no relationship between loneliness and death from cardiovascular causes ².

Regarding loneliness and its relationship with race, one study described a significant association between loneliness and risk levels of HbA1c and BMI only in older black adults ¹⁵, consistent with another study that compared relationship between loneliness and cognitive function in older adults with HIV, with a greater association in older black adults ⁸.

Finally, other relationships have been described: such as loneliness with greater symptoms of disability and a slower walking speed of 4 meters in older people with type 2 diabetes, overweight and obesity ¹⁹; others associated loneliness with memory and verbal fluency ³, as well as with the reactivation of the herpes virus ²⁷, and it was also associated with poorer mental health and unhealthy behavior ¹⁰.

CONCLUSION

The present review fulfilled the objective which was to identify the pathologies associated to loneliness in the elderly. There are multiple studies that show the relationship between loneliness and its consequences, with two trends in some pathologies. On the one hand, studies that affirmed their relationship, while others ruled it out. However, there are clear aspects in the selected studies, for example: the obvious effect of loneliness on cognitive decline, decreased physical fitness, Alzheimer's disease and cardiovascular events. On the other hand, contradictions were seen in the relationship between loneliness and the risk of death, as well as with depression. In this context, it is undeniable that further research is required in this regard, in order to clarify these relationships.

The phenomenon of “population aging” is a challenge for society, since it has to adapt to improve the health and functional capacity of older people as much as possible, as well as their social participation and safety. It is necessary to establish public policies to prepare people for their future aging process, in addition to being able to implement various strategies to prevent and/or reduce loneliness in older people.