1. Introduction

According to the World Health Organization (WHO), depression is a mental disorder that manifests itself through sadness, extreme apathy, anhedonia, feelings of guilt, low self-esteem, sleep disorders, appetite, lack of concentration, and sensation of tiredness ^[1].

The WHO estimates that depression affects more than 300 million people in the world ^[2]. In its most serious form, this disease can lead to suicide, since 800,000 individuals commit suicide each year in the world, this being the second most common cause of death in individuals between 15 and 29 years old ^[2].

Even so, depression affects all age ranges, especially vulnerable individuals such as retirees. Retirement is a transition which occurs in the last stage of life and is characterized by the ceasing of work and, with that, the loss of a routine, social relations, role, status, accomplishments, and aspirations, etc. ^[3]. This implies changing the lifestyle adopted during many years in the working stage and supposes a phenomenon that can alter the psychosocial realm of the retiree ^[4]. Additionally, the aging process supposes diverse changes in health and it would lead to the decline of individuals who suffer it, altering their self-image, self-esteem, autonomy, and functionality ^[5].

The majority of individuals understand the transition from being active in working life to retirement as the process by which they start to become old ^[3], which generates feelings of uselessness, thus predisposing them to depression.

Depression is one of the most underdiagnosed diseases and, still in the 21^st century, it is still being stigmatized or even banalized, ignoring the resources, treatments, and recovery of this cruel disease ^[6].

Research on the depression of retirees is very scarce, and few studies directly relate depression with retirement ^[7], despite the great diversity of published articles on this disease ^[8]. Currently, the publications on depression are directed to valuing different treatments to determine if they are effective such as, for example, the use of acupuncture, music therapy, and the search for the ideal antidepressant ^[9][10][11].

Although the current research lines on the search for effective treatments against depression are important, more studies should be conducted on the direct relation between retirement and depression. It is also important to know the prevalence of depression and how health professionals, including nurses, can collaborate on a psychoeducational approach to lower the prevalence figures.

The fact is that, both in health prevention and promotion, nursing plays a very prominent role to stop the progress of this disease ^[12]. Nursing is very important in early detection ^[7], apart from its fundamental contribution to the psychoeducational approach ^[12]. These health professionals are also in charge of maintaining a close relationship with patients and their relatives, so as to foster a good use of pharmacological treatments, increasing adherence to them ^[13][14] and thus preventing future relapses ^[7].

The majority of the studies included (41.6%) use “Beck’s Depression Inventory”, whose test has a high reliability with a Cronbach’s Alpha of 0.91 ^[15].

According to the results obtained in the studies included, it is concluded that the retirees with the highest prevalence of depression are the ones who retire in a mandatory fashion or due to illness ^[16][17][18].

According to the data found, the estimated prevalence of depression in retirees ranges from 0.42 to 22.7%, differentiating between mandatory and voluntary retirement, as well as by the level of depression suffered: minimum (46.7–66.7%), slight (10–40%), moderate (17.1–24%) and severe (3.8–16.7%).

According to the selected articles, the estimated total prevalence of depression in retirees is 29%. Therefore, and considering the number of retirees worldwide, this implies that one out of three retirees suffers from depression or, more optimistically, one out of four certainly suffers from this disease. Still, a greater diagnostic reliability and appropriate tools are needed to validate this prevalence data, so that we can understand how many retirees meet the diagnostic criteria for major depression.

2. Sanitary Role in the Psychoeducational Approach

Some of the articles propose the realization by primary care nursing professionals programs aimed at evaluating and assisting people who are in this period of their lives ^[16][19][20], helping people to find new activities that motivate them ^[18], encouraging them to participate in community groups ^[21], helping individuals to deal with the new situation ^[20] and finding activities that increase their self-esteem again ^[22].

According to the study carried out by Hebert and collaborators ^[16], the involvement of the family in this new stage is also important, with nursing being in charge of giving them the information necessary so that they are able to detect in time the appearance of symptoms of depression. A section of retirees heavily affected by depression, according to the study carried out by Lizaso and collaborators ^[17], are those who retire due to illness, being a field in which nursing could act in order to reduce the prevalence of depression that we find in these people.

In many cases, the transition period towards retirement is loaded with uncertainty among the population, with retirees being more susceptible to developing mental health problems ^[16]. For this reason, some of the articles included in this review suggest that the health professionals must implement programs intended to evaluate and help the people in this period of their lives ^[16][19][20], helping individuals in their search for new activities that motivate them ^[18], to encourage them to participate in community groups ^[21], to help them build the necessary will power to face the new situation ^[23], and to find activities that improve their self-esteem ^[22].

The WHO defends aging as a process in which opportunities are streamlined to have good health, social participation and self-confidence in order to enjoy a good quality of life by means of campaigning for an active aging process ^[24]. This active aging process would include not only good physical and mental health, but also social participation, thus avoiding treating older people as passive beings and full of needs ^[5]. Active aging can be applied both individually and in groups, as long as it potentiates the physical, social, and mental well-being of the elderly population; for this reason, both in society and in the socio-sanitary policies, the importance it really has by means of subsidies and promotion initiatives of this movement has to be assigned so that the population are informed. All of the above could help to reduce the great number of deaths produced after exiting the stage which society understands as active, namely the working life ^[25].

According to a study conducted by Hebert and collaborators ^[16], the commitment of the family members is also important in this new stage, the multidisciplinary team of health professionals being in charge of giving them the necessary information so that they can promptly detect the onset of the symptoms of depression. In the same line is a study by Wahyuni et al., where the relation between the elderly’s social support and the incidence rate of depression is assessed. The authors conclude that the greater the level of social support, the lower the incidence of depression will be. They stress the importance of health workers, especially nurses, since among their competences is providing health services, especially when they relate to providing social support and to the anticipated incidence of depression in the homes of the elderly ^[26].

The interchange places for retirees ^[23][22] are also mentioned, spaces where the individuals can perform activities voluntarily, participate in opinion forums with other retirees, support each other and all supervised and organized by well-trained personnel ^[27].

A group of retirees which is deeply affected by depression are those who retire due to illness ^[16][17][18], this being a field in which actions could be taken with the aim of reducing the noticeable prevalence of depression in these individuals. Even so, this study concludes that there is no direct relationship between depression and retirement, with the possibility that retiring increases the levels of depression the person has already suffered from, or that depression is the reason for retiring. In order to elucidate this, further research is needed, using longitudinal studies that allow the establishing of causality relations and verify if aging is a moderator variable in the development of depression in retirees, although there already exist studies with this type of design that have proved depression and retirement are directly related ^[28].

On the other hand, the different articles included in the review differentiate the prevalence of depression suffered by the participants of each study depending on if its level is minimum, slight, moderate or severe, or moderate, slight or high levels ^{[29][19][20][23][22]}, the percentage being higher in the case of minimum depression, which coincides and supports the importance of prevention and early detection, areas in which the health professional plays an essential role ^[30].

3. Conclusions

Based on the importance of the psychoeducational approach to depression in retirees, it is concluded that the nursing professionals have to be informed to be able to detect the signs and symptoms of depression, especially in primary care, the place where the highest level of autonomy exists and in which a good population screening should be conducted in relation to this disease. The approach of a topic as versatile as depression must be done from a multidisciplinary perspective that integrates all kinds of professionals such as physicians, nurses, psychologists, social workers, occupational therapists, etc.