1. Introduction
Bipolar disorder (BD) is a chronic and recurrent affective disorder characterized by mood and energy fluctuations, which include manic, hypomanic, and depressive episodes, along with significant subsyndromal symptoms. BD is one of the main causes of disability and it is associated with premature death due to higher rates of suicide and physical comorbidities [
1,
2].
It has also been described that multiple dimensions of aging seem to be altered in BD, leading to a premature aging process [
3]. Older Adults with Bipolar Disorder (OABD) refers to patients older than 50 years with BD [
4,
5]. Approximately 25% of all patients with BD are older than 60 and this number is expected to increase to 50% in 2030 [
6]. With the rapid aging of the world’s population and the increased life expectancy of people with chronic health conditions like BD, there is an urgent need to better characterize OABD [
7,
8].
In general, the clinical course of BD is understudied in OABD. Recently findings from the GAGE-BD project suggest some changes in the clinical pattern during the aging process. For instance, while some clinical features appear to be less severe (like manic episodes and psychotic symptoms) [
9,
10] other factors emerge more prominent, such as suicide attempts, depressive symptoms, mixed episodes, somatic comorbidities, premature death, impairment in psychosocial functioning and cognitive dysfunction or dementia [
10,
11,
12,
13,
14,
15]. In addition, some reports have detected differences according to the age of onset (early vs late), in which late onset showed poorer cognitive outcomes and higher cerebrovascular risk [
16]. Thus, OABD constitutes a more complex population due to the long-term effects of the disease coupled with the impact of aging. Older adults may face life stressors common to all age groups, as well as stressors more typical in later life, such as a gradual decline in functional abilities and capacities, forced retirement, caregiving, financial stress, and loss of independence [
17,
18]. In OABD in addition to coping with those stressors, the impact of the disease becomes an additional factor to manage such as chronic illness, cognitive decline, somatic comorbidities, loneliness, etc.
A paradigm shift towards mental health promotion is increasingly seen as an approach to improve overall well-being, helping people live better with their illness [
19]. A core aspect of well-being is resilience, which is considered one of the most important aspects of both prevention and intervention in mental illness [
20,
21]. Resilience refers to a person’s ability to adapt to, cope with and recuperate from a negative experience [
22], which can be in the form of relationship issues, health problems, work, financial concerns, among other challenges [
23]. Furthermore, resilience is seen as a dynamic multidimensional construct that not only involves personal characteristics, abilities, or skills, but also family support and other external factors [
24]. Because it also includes contextual resources, which may be learned and acquired, resilience is considered a process rather than a trait [
25]. Some “resilience factors” or coping mechanisms include an optimistic but realistic outlook, sturdy role models, an inner moral compass, religious or spiritual practices, acceptance of what cannot be changed, physical fitness, mental sharpness, emotional strength, actively solving problems while looking for meaning and opportunity, and humor [
26].
In the context of mental illness, resilience appears to moderate the risk of depression [
27], negative affect and perceived stress [
28] and is also associated with a reduced suicidal ideation [
29]. Among BD patients, higher levels of resilience have been associated with lower severity of clinical symptoms such as depression, psychotic symptoms or suicide attempts, but also with better social and psychosocial outcomes [
21]. Thus, resilience is considered a protective factor that promotes a positive outcome among people facing adverse circumstances. It is believed that resilience may be a key factor in improving health outcomes for people with BD, in areas such as psychosocial functioning, wellbeing and quality of life [
25,
30].
A challenge to understand the role of resilience in OABD, is that it could be impacted by the course of the disease, the illness stage, the severity and other clinical specific features. Furthermore, it's possible that the effects of the illness have hindered the acquisition of coping mechanisms for life stressors as less resilience is observed in BD compared to HC [
31]. On one hand, the long course of the disease frequently experienced by OABD, could impact the development of resilience strategies, affecting their functioning, quality of life and wellbeing. On the other hand, sometimes OABD is described under the concept of “survivor cohort”, which refers to the suggestion that OABD form a group of less severe patients, because those with the highest burden experience premature death. This may be related to the proposal that these older adults have acclimated to their diagnosis and symptoms and have devised effective coping strategies [
32]. Additionally, it has been noted that patients with BD who reach advanced age may even have a less severe phenotype of the disease, displaying better conditions to develop better levels of resilience and cope strategies. Thus, it appears of most noticeable importance to better characterize resilience in OABD. A better understanding of resilience could be useful for an early identification of profiles of patients who may require more assistance to foster resilience and improve management of BD [
21]. The aim of this study was to measure and characterize resilience in OABD, as well as to observe which factors are associated with it.
4. Discussion
To the best of our knowledge, this is the first study to evaluate resilience in a sample of OABD. We found that resilience was correlated with some clinical factors such as the total number of episodes, particularly depressive episodes, in which more episodes indicate lower resilience, Psychosocial functioning was also significantly associated with resilience, showing that OABD patients with better functioning exhibited higher levels of resilience. Furthermore, the sample could be classified into three groups based on resilience levels. The group with low resilience presented worse psychosocial functioning and CR compared to the group with normal resilience. Notably, the group with normal resilience consisted only of patients with EOBD.
As previously described, resilience is a multidimensional subject that relates to an individual’s ability to adapt positively in response to significant adversity [
26]. Compared to healthy controls, resilience levels in patients with BD have been described to be lower even during euthymic periods [
23]. In recent years, the CD-RISC-10 has been used in psychiatry, specifically for evaluating patients with BD, but it had never been used before to assess resilience in OABD. According to normative data, our results show that almost half of our sample exhibited low resilience, while half of the patients displayed normal resilience levels, with very few patients demonstrating high resilience.
The results of this study show a negative correlation between resilience and the total number of episodes, suggesting that with every new relapse, the resilience capacity worsens, particularly with depressive episodes. This stands in line with previous analysis, which suggests that depressive episodes have a higher negative impact on patients’ ability to manage their disease when compared to manic and hypomanic episodes. In that sense, resilience is a mediator of depressive symptoms, protecting against their onset, severity, and chronicity [
43]. Patients with a long history of BD who have experienced more depressive episodes have not been able to develop coping strategies across the life spam, increasing the risk of subsequent depressive episodes. Nevertheless, it is also possible that those patients with lower number of depressive symptoms have a neurobiological predisposition for stronger resilience mechanisms [
44]. Another important issue is the challenge of defining resilience. Resilience has often been cited as the absence of mental illness or the maintenance of mental health in the face of adversity. However, it is crucial to broaden the perspective on this concept and consider that having a mental disorder or experiencing depressive episodes does not necessarily mean one is less resilient [
45]. In fact, facing and managing such challenges often requires great strength and perseverance, demonstrating a profound level of resilience.
It has also been hypothesized that there may be an association between resilience and functioning [
25], in which patients with higher resilience show better psychosocial functioning [
21]. In our study, we have found a significant correlation between resilience and functioning, indicating that OABD with lower resilience also have poorer psychosocial functioning. This is further supported by the results from our resilience group analysis: participants with low resilience had lower psychosocial functioning when compared to those with normal resilience. This may be explained by the fact that resilience determining skills such as the acceptance and understanding stressful events, like mood episodes in OABD, having the capacity to develop coping strategies, and enjoying a sense of belonging are crucial and necessary to function both on a personal level as well as in society. On the other hand, since functioning is also related to the number of depressive episodes, which in turn are associated with the development of resilience, it could be a multifactorial and multidirectional relationship among these constructs.
Another mental health concept that has been recently discussed is that of CR [
46]. The CR hypothesis states that patients with higher IQ, education levels, or occupation attainment are less likely to develop dementia [
47]. CR can be defined as the ability of the brain to make flexible and efficient use of cognitive networks in order to minimize the clinical manifestations of the pathology [
48], and this capacity appears to be reduced in BD patients [
49]. Recent literature has proposed a possible association between resilience and CR, by complex unknown mechanisms through which resilience brain networks appear to subtend interindividual differences in terms of CR advantages [
21,
50]. Both concepts, CR and resilience, have been used to partially explain variable outcomes with respect to aging and disease considering resilience the emotional aspect of CR [
19] may another protective factor to be considered. They represent one’s capacity to use their cognitive, affective, and social skills to sustain psychological stability following exposure to stressful or traumatic events. However, we have not found a significant overall correlation between these two variables, this lack of correlation may be explained by the limitations of this study, as having a small sample may cause the appearance of type II errors. Nonetheless, after analyzing the differences between patients with normal and low resilience, CR results appeared to be significantly different, with patients with low resilience having worse CR. CR can contribute to resilience by enabling individuals to better manage their symptoms and maintain cognitive functioning, thereby improving their overall quality of life and ability to cope with the challenges posed by their condition.
Additionally, as previously described, there are two major groups of OABD regarding the onset of the disease: EOBD and LOBD. There is an ongoing debate about whether these two groups vary in characteristics and if their treatments should differ [
51]. So far, studies show that LOBD might represent a similar clinical phenotype as EOBD with respect to BD symptomatology, functionality, and comorbid physical conditions [
52], but the question stands open if these two groups may have different levels of resilience. This possibility was analyzed in the present study, and the results show that there is no significant overall correlation between the type of onset and resilience, but there was again a significant difference when comparing the groups, with the group with normal resilience being exclusively composed by participants with EOBD while the group with low resilience included participants with both EOBD and LOBD, but more cases of EOBD. These findings are interesting as they can be interpreted in different ways. On the one hand, as the group with normal resilience was only composed by patients with EOBD, this subgroup of patients may have higher resilience because they have had more time to adapt and cope with their disease, as the
healthy cohort hypothesis has stated. On the other hand, the higher proportion of patients with EOBD in the low resilience group, it could mean that the disease itself has a negative long-term impact on resilience and coping abilities. However, it would also have been expected that at least a certain proportion of LOBD patients would achieve normal levels of resilience, as in the absence of disease symptoms, they may have developed more resilient traits. In fact, in line with this notion, when examining the high resilience group, we observe that two out of the three patients in this category had a late onset. Further research is needed to clarify the differences and causes regarding the association between resilience and the type of BD onset.
This study has several limitations that must be considered. First, the small sample size may limit the interpretation of the results [
53]. Future studies including a larger sample size would enable more generalized and robust conclusions. Second, the average age of the patients who participated was relatively young, despite fulfilling older age criteria. This generates doubts about the generalizability of the results to patients in the eighth and ninth decade of life and beyond, which need to be studied considering the current aging of the global population. There was also a suboptimal number of participants in the group of LOBD, which could have impacted the results regarding the type of onset. Finally, the sample size in the group with high resilience was insufficient to allow for statistically meaningful comparison with the other groups. Another limitation lies in the definition of resilience, there is not a consensus on its definition and factors included, acquiring many nuances and depending on the scale used to evaluate it. Additionally, the scale used to measure resilience is self-administered, which implies limitations associated with self-reported information, which, in the context of mental illnesses, may be mediated by clinical status and cognitive difficulties. Finally, treatment was naturalistic and therefore medication might have been a confounder in some analysis [
54].
To conclude, this study has evaluated resilience in OABD, and the results have shown that these patients may have lower resilience than healthy subjects of their same age group. Also, an association has been observed between resilience and the total number of psychiatric episodes, and specifically the number of depressions. Furthermore, the results show that patients with lower resilience have worse psychosocial functioning, lower CR, and higher rates of EOBD. One of the key questions arising from this study is which patients might benefit most from therapy specifically aimed at strengthening and enhancing resilience and its coping mechanisms. Therefore, it seems it may be the group of OABD with more depressive episodes who may benefit to a greater extent from resilience-enhancing treatments, also suggesting that may subsequently improve their overall functioning and quality of life. Further studies are needed to explore resilience and clinical factors such as the severity, the long-term impact, or the course of the disease.
Author Contributions
Conceptualization, Laura Montejo; Methodology, Laura Montejo and Monica Retuerto; Software, Laura Montejo and Monica Retuerto; Validation, Laura Montejo, Eduard Vieta and Carla Torrent; Formal analysis, Laura Montejo and Monica Retuerto; Investigation, Laura Montejo and Eduard Vieta; Resources, Laura Montejo; Data curation, Laura Montejo, Monica Retuerto, Sara Martin, Andrea Ruiz and Marta Bort; Writing – original draft, Laura Montejo, Monica Retuerto, Andrea Ruiz and Carla Torrent; Writing – review & editing, Laura Montejo, Monica Retuerto, Brisa Sole, Sara Martin, Derek Clougher, Marta Bort, Anabel Martinez-Aran, Eduard Vieta and Carla Torrent; Visualization, Anabel Martinez-Aran, Eduard Vieta and Carla Torrent; Supervision, Laura Montejo, Eduard Vieta and Carla Torrent; Project administration, Laura Montejo; Funding acquisition, Jose Sanchez-Moreno and Anabel Martinez-Aran.
Conflicts of Interest
EV has received grants and served as a consultant, advisor, or CME speaker for the following entities: AB-Biotics, AbbVie, Angelini, Biogen, Biohaven, Boehringer-Ingelheim, Celon Pharma, Dainippon Sumitomo Pharma, Ferrer, Gedeon Richter, GH Research, Glaxo-Smith Kline, Idorsia, Janssen, Lundbeck, Novartis, Orion Corporation, Organon, Otsuka, Sage, Sanofi-Aventis, Sunovion, Takeda, Teva, and Viatris, outside the submitted work. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.