Over the past few decades, the average human life expectancy has increased ever in the world. The world's population is aging faster than it did in the past, with 9.3% of the population aged 65 or older in 2020, and projected to reach 17.0% by 2050 (OECD, 2022). Increasing population aging has far-reaching consequences such as declining productivity, intergenerational inequality, and the burden of public finances, which various countries around the globe face a variety of challenges relating to the aging population (Rouzet, Sánchez, Renault & Roehn, 2019).
Many under-represented issues in the lives of older adults have been neglected due to the fact that they span multiple domains; pain is one of the issues. Sensations of pain are transmitted to the brain through the spinal cord, which is more noticeable among the aging population and can produce more pain as the older adults' nervous system adapts to these changes (Cruz-Almeida, Aguirre, Sorenson, et al., 2015). However, pain in old age is hardly understood, and it occur on a routine basis without being adequately evaluated. Since pain is such a common issue, the idea of embracing it as a natural part of aging among people is prevalent in our society (Chakour, Gibson, Bradbeer, et al., 1996; Kumar & Allcock, 2008). Older people may regard their pain as incurable and may lead to not seeking appropriate medical treatment (Schofield, 2007). As such, it is hard to manage pain efficiently when individuals or society recognize that increased pain is a typical symptom of getting older.
With this insight, the International Association for the Study of Pain (IASP) was founded in 1973 to lead diverse pain studies (Raja, Carr, Cohen, et al., 2020). IASP defined pain as “An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage” (Revised IASP Definition of Pain, 2020), and it has been adopted by several experts, including the World Health Organization (WHO). In this revised definition after 1979, pain cannot be inferred as sensory activity alone, but it must be viewed from the perspective of the person experiencing pain, by emphasizing the negative social and psychological effects of pain. In other words, regardless of a physical injury, it was emphasized that comprehension should not be compromised for those who are experiencing subjective pain. In spite of pain appearing in all age groups, the theme of the 2019 Global year of advocacy was chosen to highlight the needs of the aging population, who are exposed to high vulnerability and potential risks.
The risk of pain in the aging population has also been reported academically. Pain is estimated to occur in 45–90% of the aging population (Brown, Kirkpatrick, Swanson & McKenzie., 2011; Ferrell, 1991; Ranjan Roy, 1986); the lack of awareness of pain (Ferrell, 1991), the age difference of the study subjects (Harkins & Price, 1992), and different measurement (Gagliese & Melzack, 1997) all contribute to the wide disparity in prevalence. However, significant evidence of pain with increasing age has been consistently reported (Badley & Tennant, 1992; Crook, Rideout & Browne, 1984). In addition to the risk of difficulty in daily living activities (Cha & Park, 2011) and disability (Soldato, Liperoti, Landi et al., 2007), pain in old age, if not properly treated, may increase the possibility of chronic pain (Molton & Terrill, 2014) and may aggravate symptoms such as depression (Casten, Parmelee, Kleban et al., 1995; Kaye, Baluch, & Scott, 2010).
Although there are significant differences in pain according to gender and marital status, it is reported that the higher the age and the longer the pain period, the greater the negative impact on life. Although there are substantial disparities in pain according to gender and marital status, it is reported that the older one gets and the longer the pain lasts, the worse the influence on one's life becomes (Cha & Park, 2011). Furthermore, since pain increases societal responsibility and burden, a thorough investigation of how pain affects and impacts older adults is required.
Growing life expectancy has resulted in increased academic interest in pain in the aging population, and epidemiology studies focused on the quality of life among older adults have been flourished. Most attention has traditionally been paid to the prevalence of depression among older individuals. It was the results of studies examining not only the effects of depression on older people, but also factors that contribute to depression among older adults, including gender (Blazer, 2003), age (Meller, Fichter & Schröppel, 1996), socioeconomic status (Wilson, Taylor & Copeland, et al., 1999), and living alone (Blazer, 2003).
Particularly, it has been reported that there is a strong relationship between depression and pain in older adults. While the dynamics of pain and depression are similar, the fact that depression is a consequence of pain over time facilitates a better understanding of the mechanisms behind pain and depression among older adults (Fishbain, Cutler & Rosomoff, 1997; Kaye, Baluch & Scott., 2010; Williamson & Schulz, 1992). Williamson & Schulz (1995) have identified evidence of age differences and the prevalence of distinct persistent pain among older adults. This indicates that the effect of aging on an individual's pain experience is fairly complex, suggesting that a comprehensive examination of pain changes is required.
Yet, it is difficult to find studies that examine how a change in the type of pain affects depression in older adult. In spite of some studies that have examined the variability of pain (Casten, Parmelee, Kleban et al., 1995), it is surprising that studies on the correlation between pain and depression have been overlooked. The longitudinal relationship between the types of pain changes and depression in the old age will be essential when establishing long-term strategies for coping with pain-psychological effects among older adults. Furthermore, considering the fact that pain negatively affects older adults, an in-depth review should be undertaken by categorizing changes in pain. Hence, the purpose of this study is to identify the types of pain changes that affect older Koreans 65 years and over, as well as their effects on depression.
To accomplish this research purpose, the research questions set in this study are as follows. First, how do pain changes affect old people (over 65)? Secondly, how does the type of pain change in older adults affect depression?