The World Health Organization [1] reports that suicide in older adults is a global health problem. The over-65 year age group has the highest suicide rate in most countries that report suicide statistics to the WHO [2] . Countries with high rates of older adult suicide include European Union states, Canada, the US and some Asian countries such as Japan, Singapore and Taiwan. In many countries, older adult suicidal behaviour is lethal, as non- fatal suicidal acts tend to be less common in this age group [3] . In the US, up to 75% of older adults die as a consequence of their first suicide attempt [4] . Mental disorder is present in 71% - 97% of older adults who die by suicide, depression being the most common diagnosis [4] . A meta-analysis showed reduced suicide rates in several communities that were exposed to interventions in Japan, particularly in women [5] . The available literature indicates various predictors of suicide in old age [6] [7] . Stressful life events such as the loss of one’s spouse have been found to have a significant correlation with increased suicide risk in older adults [8] . Qualitative studies have revealed that the participants experience the final phase of life as a burden and seem to accept death [9] [10] . Rurup et al. [11] stated that the older persons in their study gradually developed suicidal ideation after a life full of adversity and as a consequence of ageing, illness or recurring depression. Holm et al. [12] described that the older participants in their study experienced the situated meaning of survival as “shadows from the past”―a feeling that something inside is broken, forcing them to struggle to catch the light. Joiner [13] develops the Interpersonal Theory of Suicide (ITS), which proposes that in order to complete suicide, one must have both the desire and ability to carry out the act. Desire for suicide contains two important components: perceived burdensomeness to others and a thwarted sense of belongingness [13] . Joiner’s [13] states that the desire for suicide arises when a person perceives her/himself to be a burden on significant others. In addition, she/he must have a sense of thwarted belongingness, or lack of social connectedness through meaningful relationships [13] .

Collaborative care models for depression involving expert mental health consultation, medication recommendations, psychotherapy and psycho-education have reduced suicidal ideation among older adults in the US [14] [15] . In Norway, a qualitative implementation project using the Chronic Care Model (CCM) revealed psychosocial aspects such as stigma and social exclusion that can increase suicidal behaviour in depressed older persons in the community [16] - [18] . The systematic review by Fässberg et al. [2] demonstrates that most depressed older people do not die by suicide and that there are modifiable risk markers that can be targeted before the emergence of depression, suicidal feelings and other risk factors for suicide mortality. Social factors constituted important aspects in this context [2] . Carli et al. [19] state that the strongest predictors of serious suicidal behaviors (SSB) seem to be older age and not professing a religion. A review by Van Orden and Conwell [20] reveals that social disconnectedness in combination with depression, somatic disease and functional impairment is a major risk factor for suicide.

There remains a paucity of research on the specific contribution of psychosocial aspects to suicidal ideation in older adults. Studies have used various social support constructs (i.e., social network, social interaction, social isolation and family discord) that include objective and subjective measures. Few studies employed different types of social support indices as predictors of suicidal ideation in older adults. Social aspects associated with suicidal ideation in older adults include a limited social network and living arrangements that allow few contacts with friends or relatives [21] [22] . Lack of self-confidence and social support are also reported [23] [24] .

The aim of this study was to identify psychosocial risk and protective factors in suicidal older persons. The research question was: What psychosocial risk and protective factors for suicidal older persons are found in the literature?

We systematically searched for and synthesized evidence of psychosocial risk and protective factors in suicidal older persons [25] .

The psychosocial risk factors were categorized under four themes: Being a burden to others increases depression and hopelessness, The struggle due to poor social integration, The strain of physical illness and old age and Negative aspects of religious activity. In terms of protective factors four themes emerged: A sense of belonging, maintaining social dignity, satisfaction with relationships and feeling useful and Positive aspects of religious activity.

The aim of this study was to identify psychosocial risk and protective factors in suicidal older persons. The research question was: What psychosocial risk and protective factors for suicidal older persons are found in the literature?

Being a burden to others increases depression and hopelessness, thus constituting a greater risk of suicide in older persons [33] [40] . Being a burden to others or perceived burdensomeness has been considered an important factor when determining suicide risk in older adults and an explanation for why depression sometimes leads to suicide [44] . The two main components of perceived burdensomeness are liability and self-hate [45] . Being a burden includes less fear of death, increased tolerance of physical pain and being troubled by traumatic memories as well as past experiences [12] . Risk of suicide in depressed older persons was caused by a sense of hopelessness [33] [40] . Thus an association between perceived burdensomeness, depression and suicidal ideation seems to exist [46] [47] . However, it is important to bear in mind that not all depressed persons experience suicidal ideation, while some individuals who report suicidal ideation do not suffer from depression [8] . Nevertheless, in previous studies depression has been described as a risk factor for an escalation of suicidal ideation [24] [48] .

The struggle due to poor social integration comprised a struggle against others, a poor social network and lack of social support, all of which increased the risk of suicide [30] [32] [34] [35] . These findings are supported by Durkheim’s [49] early observations on social integration. A poorly integrated social network, loneliness and lack of support from service providers hindered integration into the community. Previous research has suggested that successful ageing includes a sense of self-confidence thanks to integration into small, closely knit social networks [50] . Lack of social support and problems in social relationships were associated with increasing suicidal experiences [51] -[53] . Thus elderly persons’ psychosocial requirement for a sense of well-being and to be needed is more important than the number of people in their social network. In everyday life the quality of social support can be affected by the degree of dependency and interdependency between parties [16] [17] . Older persons feared becoming increasingly dependent on family, desired a guardian and wished to be independent. The links between material support and death ideation can be explained by the fear of becoming increasingly dependent, thus leading to a higher risk of suicide [54] . Perceived lack of social support in elderly depressed persons was described as increasing guilt, worthlessness and distorting the perception of available support [55] . Such distorted perceptions can lead to a lack of ability to show emotions, which can impair the capacity to experience social support [9] . Social cognition seems to be a prerequisite for the ability to communicate, collaborate and show empathy. Emotional difficulties can influence the social and cognitive dimensions of depression as well as causing a sense of hopelessness in suicidal adults [56] . Poor communication skills can be related to difficulties in recognizing emotions, thus contributing to social and mental health problems, described as psychopathology [57] [58] .

The strain of physical illness and old age was associated with suicidal ideation [31] [32] [36] [41] . Physical health problems have been reported as increasing the risk of suicide in elderly persons [8] [35] [52] [53] . The importance of assessing the risk of suicidal ideation among older adults struggling with health problems has been described in previous research [31] . In the study by Holm et al. [16] , the participants suffered from depression and various physical health problems. They reported experiencing a sense of living with stigma and longed to be taken seriously by the healthcare system. In addition, they had a sense of living in a war zone.

Negative aspects of religious activity. Heisel and Flett [31] revealed an unexpected association between heightened suicidal ideation and increased frequency of religious activities and rituals. According to Braam et al. [59] , one explanation can be that high levels of religious observance among secular older adults are associated with severe depression. They may believe that they have no hope of being saved and the fear of being alone can become stronger, especially when depressed. Previous studies revealed that depressed elderly persons struggle with ‘relational baggage’ [60] . Their self-management ability should be strengthened based on an understanding of their situation, perspectives and vulnerability.

A sense of belonging was described as a protection against suicide [32] [38] [39] . It can be related to an experience of being valued in relationships, being independent as well as the ability to feel cared for and care for others [45] . However, some researchers have criticized individual aspects of this model [54] [61] . Previous research has indicated that males report a lower sense of belonging than females [39] and that the relationship between sense of belonging and depression is stronger for women than for men.

Maintaining social dignity involved self-acceptance. A sense of well-being can protect against suicidal ideation [31] . Human dignity is described as a human being’s freedom, which is tied to the responsibility of being human [62] . Social dignity can be understood as part of human dignity and the responsibility we all have for each other. Relationships and interactions with other people are essential as all human beings have the same need to be treated with decency and respect [63] . Frankl’s [64] concept of meaning in life seems to protect against despair and suicidal contemplation, thus can facilitate suicide resiliency among people at risk. However, a future orientation may be less relevant to elderly persons, as in old age the perception of meaning in life may turn from future possibilities to past accomplishments, which corresponds to the successful resolution of Erikson’s [65] integrity of ego.

Satisfaction with relationships and feeling useful was associated with personal growth and self-acceptance [30] [31] . The findings must be seen from the perspective of elderly persons receiving nursing care in their homes, a time in which they are often confronted with physical, emotional and social changes that are likely to be overwhelming for them and their families. Requiring assistance in their home from “strangers” may elicit feelings of dependency, loss of autonomy or shame. One needs to expand the elderly persons’ possibility to talk about issues such as thoughts of death because they are less likely to report suicidal experiences [18] . Elderly persons may have “normal” thoughts of death due to the burden of functional disability and social isolation. Healthcare professionals should engage them in discussion, particularly about their perception of lack of social support, thus providing an opportunity to uncover suicidal ideation. Satisfaction with social relationships is an issue of concern because the perception of social support can be important for uncovering suicidal ideation. Social relationships can function as a ‘safety net’ and protection during stressful life events such as functional decline, physical and emotional pain or the death of a spouse.

Positive aspects of religious activity were seen as a protection against suicide [31] [41] . Motivating elderly persons to engage in religious activities seems to increase opportunities for social support, which may serve as a buffer against suicidal ideation. A recent literature review indicated that religious and spiritual factors, social cohesion and prosocial behaviour prevented suicide among African Americans [66] . However, cultural minorities can find meaning in religion, which is not the case in elderly adults in white cultures [67] . The fact that social support is related to a sense of belonging, as stated by Joiner [13] , can partly explain why religious activity decreases suicidal ideation. As social support appears to decrease mental distress and suicidal ideation, religious activitycan sometimes protect against suicide [68] .

Risk of bias will be discussed in this section, as suggested by Schneider et al. [29] and Polit and Beck [27] . Bias is defined as influence that produces a distortion in the results, thus threatening validity and trustworthiness [27] . Five of the included studies have a cross-sectional design, one a longitudinal design [36] and one is described as a case-control study (see Table 1). Descriptive/explorative, correlation, cross-sectional, retrospective, cohort and longitudinal studies can employ an observational design. The studies that have no exact description of design can be designated correlation [40] and descriptive studies [38] [39] [41] , which means that these authors employed an observational design. Observational designs can have limitations in their ability to determine “causality” [29] , which was mentioned as a limitation in six studies [30] [32] [34] [39] -[41] . The implications of studies with an observational design could be weakened by the fact that participants can change over time. Polit and Beck [69] called this the “history and/or maturity threat”. Using one group as described by six studies [30] [31] [35] [38] -[40] , could be affected by the history threat, thus increasing bias. A longitudinal design typically requires the participants to retrospectively summarize the extent to which they employed various strategies over a long period and is more likely to produce inaccurate results due to memory bias, compared to measurements that focus on shorter time periods. However, none of the included studies stated that the retrospective design could decrease validity and/or trustworthiness. Six studies described how the lack of prospective data could make it difficult to know exactly what was being investigated and that the small number of significant findings might be a product of the long-term retrospective nature of some participants’ reports. Six studies described that future research requires prospective [35] [40] and/or longitudinal data [30] [32] [33] [41] . A prospective design starts with a presumed cause and continues with a presumed effect [69] . Prospective studies are needed to determine the relevance of the findings [34] [35] .

All the included studies used self-reports as measurements. According to Shadish et al. [70] , self-reports can increase the likelihood of response bias. Heisel and Flett [31] discussed a potential limitation in terms of reliability and validity as a result of using a single item measurement that might be problematic among older adults with hearing impairments, as it could increase the possibility of misunderstanding an item. None of the included studies mentioned self-reports as problematic for validity. McLaren et al. [39] found a limitation if there was a possibility that the results had been confounded by common method variance. Jahn et al. [40] mentioned that all self-report measures might not be as sensitive to a full range of symptoms compared to a clinician-administered interview measure. A weakness was that two of these studies lacked references to methodology [39] [40] .

Statistical power depends on sample and effect size, while non-significant implications must be interpreted with caution [29] [70] . Heisel and Flett [31] stated that their findings are limited by the cross-sectional methodology and the largely homogeneous cultural sample. The non-significant findings in two of the studies can be related to selection bias [34] [35] . Mellqvist et al. [35] stated that their results were no longer significant after adjustment for sex, age and major depression. Failure to show significance was described as due to lack of power. However, this information was not related to the methodological literature. Six studies have a relatively small sample size from 80 - 126 (Table 2), but did not mention selection bias as a limitation. Three studies used a control or comparison group while nine employed only one group (Table 2). The limitation of using only one group is not mentioned as leading to a risk of bias in these studies. Bias is one of the major limitations of a case control study due to inability to control confounding variables that influence the outcome [71] .

A limitation of this review is the fact that four of the studies come from the USA, one from Canada, five from Europe and two from Australia (see Table 1). The different cultures in these parts of the world must be taken into consideration; for example, other countries might have a different way of registering psychosocial risk and protective suicidal behaviour in clinical settings. Further studies in other countries are recommended, where the researchers need to strengthen the design, validity and reliability of the quantitative studies.

The studies examined included a broad spectrum of content, outcome measurements and statistical analyses across different time periods, making a meta-synthesis appropriate [26] . The search strategy could be a limitation, as the possibility of excluding relevant studies is ever present. The number of studies published is increasing and new evidence could easily change the relevance of a review in terms of dependability, which refers to the stability (reliability) of data and conditions over time [27] . A thematic analysis can have limitations in exploring data [43] .

The aim was to identify psychosocial risk and protective factors in suicidal older persons based on the literature. However, Holopainen et al. [42] suggested that one can never be sure that all relevant studies are included in such a systematic review. There is always a possibility that some important aspect has not been found. In order to ensure trustworthiness, the authors tried to avoid bias by not focusing on one study at the expense of another, as recommended by Pope et al. [43] .

This review shows that psychosocial risk factors are dominated by depression, physical illness, the ageing process and social factors. The context of suicidal older persons receiving home healthcare service may create a “vulnerable psychosocial state” with stressful psychosocial life events including physical illness and a changed social network. The fact that protective factors are solely related to social factors should be taken into consideration in future prevention studies. Community administration and leadership must develop contexts favourable to social and community participation of suicidal older persons, thus increasing their social dignity. As this review reveals, the assessment of perceived burdensomeness can be important for making decisions about suicide risk.

We want to thank Gullvi Nilsson and Monique Federsel for reviewing the English language.

Part of the study was supported by grants from the Research Council of Norway, “Chronic Disease Management― Implementation and coordination of healthcare systems for depressed elderly persons” (NFR, No. 204238/V50) and Department of Health Science, Stord/Haugesund University College, Norway.