Defining loneliness in older adults: protocol for a systematic review

Improved life conditions, higher longevity, and increased life expectancy have made aging a dominant phenomenon in communities leading to rise of elderly population. It is estimated that, in 40 years’ time, the population of people above 60 years of age will be doubled in the world [1]. Thus, the ratio of people above 60 years to the rest of the world population (which was 11% in 2006) will reach to 22% in 2050 [2‐5]. It is also predicted that the proportion of old people in developing and developed countries will reach to 80% and 40%, respectively [4, 6‐9]. This rising has become a serious economic, social, and health challenge for health care providers, family members, and societies in the twenty-first century [10, 11].

Apparently, the nature of old age provides conditions for feeling lonely. In other words, it puts individuals in conditions under which people feel lonelier [12, 13]. Loneliness is an internal, unpleasant subjective experience that begins when an individual’s social network undergoes a qualitative or quantitative loss [14‐17]. Loneliness is different from being alone or living alone. In fact, a person may suffer from feeling of loneliness even in the presence of other people. On the contrary, an individual may live alone but does not feel lonely [18, 19]. Some studies have reported that the prevalence of loneliness in the elderly in various European countries range from 3 to 34%. It has also been demonstrated that loneliness is lower among North European countries such as Denmark, Germany, Sweden, and Britain compared to other countries in Eastern and Southern Europe [20]. It is estimated that as high as one-third of the elderly experience some degree of loneliness at the end of their life [21‐23]. Even older adults face an elevated risk of loneliness as they age, especially those aged 80 and over [24]. As suggested, about 50% of those aged 80 and over report frequent feelings of loneliness [25]. However, this high prevalence indicates that loneliness is a serious threat for the elderly population and must be taken seriously.

It has been suggested that several factors might contribute to loneliness among elderly people. A review of the available literature illustrates that spouse loss, declining health, reduced social relations, and hospitalization are some of the factors that worsen loneliness among the elderly [26, 27]. From another perspective, loneliness among the elderly can be attributed to increasing functional disability and decreasing social contacts [28, 29]. Pinquart and Sorensen carried out a meta-analysis and found that loneliness was associated with age, gender (females feel lonelier), socioeconomic status (individuals with lower socioeconomic status feel lonelier), and place of living (people who live in nursing homes are lonelier) [30]. Yan and Yang conducted a cross-temporal meta-analysis focusing on the rising feeling of loneliness among Chinese elderly between 1995 and 2011. They reported that factors such as urban life, divorce rate, and unemployment rate influenced the degree of feeling lonely among Chinese elderly [22]. In fact, the findings suggest that keeping traditional ways of life and working toward minimizing the divorce rate would result in better social integration and less loneliness of older adults. Perhaps other pertinent goals should be to improve quality of life for older people.

Loneliness can cause physical and mental disorders experienced by the elderly [18, 31]. Various studies have indicated that loneliness will have serious health-related consequences including depressive symptoms, cognitive decline, intense feelings of emptiness, abandonment, frequent visit of doctors, and poorer quality of life [32‐34]. Loneliness also increases the risk of committing suicide [35].

Having read the literature, one might argue what constitutes loneliness above all? Various definitions of loneliness have been proposed in different studies. According to one definition, loneliness is a complex mental excitement which is generally experienced in the form of an unpleasant feeling of stress due to lack of connection or commonality with others [14]. Based on another definition, loneliness is a complicated feeling with psychological and social dimensions and is regarded as an important indicator of well-being in humans [36]. Perlman and Peplau believe that loneliness is a mental, unpleasant, and distressing phenomenon that is the result of inconsistency between individuals’ expected level of social relations and the real level of connections that is exercised [16]. It is thus argued that loneliness is the outcome of inconsistency between expected strength of social networks and the quality of these relations that is experienced in reality [17].

The concept of loneliness was initially studied in disciplines such as psychology and social work [37]. In these studies, loneliness was conceptualized existentially, pathologically, and sociologically as a depressive symptom [38, 39]. However, later on, health scholars and those who involved in geriatrics touched the topic and proposed different descriptions for loneliness among elderly populations. For instance, in a study conducted by Karki (2009), the concept of loneliness was investigated among old women. Accordingly, loneliness was divided into five categories including marital status (being a widow or not), health condition, immigration, lifelong single hood, and social isolation [40]. However, currently, researchers are trying to further clarify the definition of this concept (i.e., loneliness) since understanding this notion from old people’s perspective can enhance health care and rehabilitation services, preventing it, and providing necessary interventions [37]. Without a correct understanding of concepts, various phenomena cannot be appropriately explained and professionals will not be able to share a common language [41]. Analyzing the concept of loneliness from the elderly’s viewpoint can help us to come up with essential components and guidelines that may influence clinical research and practice. However, studies on the concept of loneliness among elderly are very limited. Most studies only focus on the strength of this feeling and its correlates. Therefore, the current study aimed to come up with a comprehensive description of loneliness among elderly by investigating available literature. Of particular importance to this study is addressing the following three research questions:

Over the past two decades, numerous observational and interventional studies have investigated the concept of loneliness. Nevertheless, this important health problem still suffers from the lack of a unique and accurate definition. Thus, all the reviews conducted in this area are inconsistent because they have focused on various research samples, research designs, and contexts. Because of inconsistent definitions of loneliness, these reviews are biased studies to one degree or another. The results of this systematic review can present a more accurate definition of loneliness for researchers who aim at conducting new primary and secondary studies on this subject. Furthermore, the results can have an important role in improving the internal consistency of future evidence.