Mental disorders constitute a global public health challenge, with almost 450 million people suffering from them worldwide (1). Mood disorders are among the most prevalent and debilitating mental conditions affecting world population. They are the second most common category of mental disorders after anxiety disorders, and contribute to an increase in mortality among those affected (2). Mental disorders affect individuals’ current functioning, as well as their quality of life (QoL) and life satisfaction (3). The symptomatology of mood disorders is very rich and varied. Individual symptoms occur with different frequency. Primary symptoms include depressed mood, a lack of energy, objectively visible psychomotor retardation, anhedonia, and a lack of self-esteem (4). Mental disorders are related to individual factors, as well as social support, culture, social protection, standard of living, and other environmental issues (5). Therefore, treatment adherence is important, but a challenge in treating serious mental disorders (6).

Adherence to treatment recommendations is defined as the patient’s acceptance of and compliance with basic health and treatment suggestions; this definition covers various aspects, such as access to treatment, taking medications, and understanding further advice (7–9). The WHO defines medication non-adherence as “a case in which a person’s behavior while taking medication does not conform to the established recommendations of medical personnel” (10). The term “treatment adherence” is therefore broader than “medication adherence”, which refers only to prescribed medications. A review of the literature indicates that treatment adherence is difficult to achieve, and is an obstacle to achieving good clinical outcomes in people with severe mental disorders (11). Patients with serious psychiatric problems are most likely to fail to adhere to medication due to poor reasoning and lack of knowledge about their illness and treatment (8, 12, 13). In turn, non-compliance with taking psychotropic drugs can lead to exacerbation of the disease, reduce the effectiveness of treatment or make the patient less amenable to subsequent treatment. Other consequences include: rehospitalization, worse QoL, recurrence of symptoms, and increased suicide rates (14–16). Since non-adherence is recognized to elevate the risk of unfavorable clinical outcomes, patient-specific non-adherence risk should be evaluated, and individuals at high risk for non-adherence should be closely monitored (17). However, it should be mentioned that some researchers have not found a direct positive effect of medication adherence on the functioning of patients with mood disorders (18).

Stress coping involves cognitive and behavioral strategies used by people facing stressful situations and life events (19). The choice of stress coping strategies has an impact on how patients perceive the symptoms they experience, and how they deal with them. Coping can be defined as thoughts and behaviors that are used to handle internal and external demands of situations perceived as stressful (20). A review of the literature indicates that coping styles are closely related to an individual’s health, and is a mechanism in between stress and disease. If patients’ coping is not effective and properly managed, it may have a negative impact on both their QoL and mental state (21). Active coping strategies have been shown to improve psychosocial functioning, while maladaptive strategies (e.g. pondering on negative states) have been linked to increased depression (22). Apart from influencing the course of the disease, various coping strategies (e.g., low levels of acceptance and high levels of denial) are associated with poor adherence to treatment recommendations (23). Denial is defined as a lack of belief in the existence of a stressor or an attempt to recognize the stressor as untrue, while acceptance is the awareness that a given stressful situation is real and should be dealt with (24). Acceptance is associated with many benefits, for example it makes it easier to cope with the disease and is a key predictor of recovery (24, 25). A review of the literature indicates that patients with mood disorders tend to use maladaptive or emotion-oriented strategies (26), which may affect their QoL, perception of their own illness, and adherence to treatment recommendations.

According to recent reports, so far no factors have been identified that affect treatment adherence among patients with mood disorders. There are a number of potential variables that may affect adherence to treatment recommendations. These may be related to the patient (socioeconomic characteristics, perceptions, beliefs), the doctor (doctor-patient relationship), the treatment (efficacy, side effects, drug dose, number of pills, number of medications), and the type of disorder (severity of illness). Each of these risk factors can affect adherence and interact with other factors. Therefore, it is important to examine the variables that increase or decrease adherence. The main objective of our study was to assess the impact of the subjects’ stress coping styles on their therapeutic adherence, life satisfaction, disease acceptance, and QoL.

Once an accurate diagnosis is provided and appropriate medications are prescribed, treatment adherence plays an important role in achieving good health outcomes and maintaining good quality of life in patients with mood disorders. Non-adherence is a barrier to effective treatment.

A review of the literature indicates that there are few publications on the effects of stress coping styles on treatment adherence, life satisfaction, acceptance of a disease, and QoL among people with mood disorders. Our study is probably the first to assess the impact of stress coping styles on psychological variables in this population.

In our study, the main stress coping style significantly affecting the examined psychological variables was emotion-oriented coping. It was found to influence acceptance of a disease, QoL, and life satisfaction. Patients who made greater use of this style were characterized by significantly lower acceptance of the disease and lower life satisfaction. Poor QoL was mainly noted in the dimensions of general health (GH), social functioning (SF), role emotional (RE), vitality (VT), mental health (MH), and physical function (PF), as well as in physical component summary (PCS) and mental component summary (MCS). We also observed that distraction (engaging in alternative activities) had a significant effect on vitality (VT) and adherence in chronic diseases. Patients who used this style to a greater extent achieved substantially higher scores for adherence, and had significantly lower QoL in the vitality (VT) domain than the rest of the respondents. Task-oriented coping affected the domains of role physical (RP), mental health (MH), as well as physical component summary (PCS) and mental component summary (MCS). Seeking social contact, on the other hand, is related to the domain of mental health (MH).

A study by Szeliga-Lewinska and Landowki showed that people from the clinical group were characterized mainly by an emotion-oriented style, while the general population more often used task-oriented coping. In terms of personality traits, people with depression had higher levels of neuroticism, while the level of extraversion was higher in the control population (33). Similar results were obtained by Borowiecka-Karpiuk et al. in their study of people with depressive disorders or bipolar disorder, the dominant stress coping style was focused on emotions (34). McWilliams et al. found that emotion-oriented coping was associated with depression (35). Suh et al. used the CISS and the Beck Depression Inventory (BDI) to analyze similarities and differences in stress coping strategies in a group of 135 people with bipolar disorder and 100 people with depressive disorders. They found that the severity of depressive symptoms can affect the style of coping with stress, therefore the authors divided the group with bipolar disorder into patients with and without depressive symptoms, and the group with depression into patients with and without exacerbation of symptoms. Thanks to this division, it was noted that patients with bipolar disorder and depressive symptoms were less likely to use task-oriented coping and avoidance-oriented coping, and more likely to apply emotion-oriented coping than bipolar patients without depression (36). A review of the literature indicates that many people with mood disorders choose maladaptive methods of coping with the disease (37–41).

Alemayehu et al. (42) demonstrated that poor QoL of patients with depressive disorders was significantly linked to their non-adherence to treatment recommendations. Similar results were obtained in a study conducted as part of the EU National Health and Wellbeing Survey (NHWS) (43). The likely reasons for this phenomenon may be the fact that patients with chronic conditions (including depression) do not adhere to treatment due to social, physical and mental health problems, which are indicators of poor QoL (44, 45).

Pacian et al. (46) found no statistically significant differences between the risk of depression and overall QoL. It has been observed that with older age, depression becomes more common and QoL in the mental and social domains decreases. Makara-Studzińska et al. (47), on the other hand, confirmed a significant relationship between the severity of depression and QoL in the physical domain in schizophrenic patients, and Daly et al. (48) informed that depressive disorders negatively affected QoL.

Kelly et al. (49) provided evidence that people with mood disorders showed more emotional reactions, which was associated with choosing maladaptive coping styles by both women and men. Furthermore, in women, greater control over depression was related to more adaptive coping strategies.

Treatment non-adherence is a serious challenge in the treatment of patients with mood disorders. Individuals who do not adequately follow treatment recommendations often resort to alternative activities as a mechanism for coping with difficult situations. Patients who predominantly adopt an emotion-oriented coping style tend to experience lower life satisfaction and greater difficulty accepting their condition compared to their peers. Conversely, patients who adopt a task-oriented coping style report better QoL than those who rely on emotion-oriented coping or alternative activities. Additionally, patients who actively seek out social contacts tend to enjoy a significantly higher QoL than those who are less likely to use this coping style.

Our study has some limitations. Most data were measured using self-report questionnaires, which may have led to biased reporting of experiences. Our study is cross-sectional, so the current study is unable to demonstrate a temporal causal relationship between treatment non-adherence and the main potential contributors. Another limitation pertains to the sample size. The Polish sample was not representative, which limits the ability to generalize the results to other populations.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving humans were approved by Bioethics Committee of the Pomeranian Medical University in Szczecin (KB-0012/153/17). The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

AJ: Writing – review & editing, Project administration, Methodology, Formal analysis, Conceptualization. DS-M: Writing – review & editing, Validation, Software. KR: Writing – review & editing, Investigation, Formal analysis, Data curation. AR: Writing – review & editing, Formal analysis. MP: Writing – review & editing, Data curation. ĆD: Writing – review & editing, Supervision. EG: Writing – review & editing, Resources, Funding acquisition. AC: Writing – review & editing, Writing – original draft, Visualization, Methodology, Conceptualization.