Several studies have analyzed the differences in MiL between people diagnosed with mental disorders and the differences in MiL according to diagnosis. Schulenberg et al. (2011) found that patients with different mental disorders (schizophrenia-spectrum, schizoaffective disorder, major depressive disorder, and bipolar disorder) reported lower levels of MiL than people without a diagnosis of mental disorder, and a non-significant interaction between the diagnosis and MiL one-year after diagnosis in people with schizophrenia-spectrum disorders, major depressive disorder, and bipolar disorder. Volkert et al. (2014) observed that people with depressive disorder showed a lower level of MiL than healthy controls and those with anxiety disorders, adjustment disorders, somatoform disorder, personality disorders, among others. Marco, Pérez, et al. (2017) found that patients with borderline personality disorder showed a lower MiL than people with mental disorders without borderline personality disorder, due to their greater sense of emptiness, identity disturbance, and confusion. The results of these studies indicate that people diagnosed with mental disorders score lower in MiL than those that do not suffer a mental disorder.

Interesting results were found by Roberts (1991) and Fervaha et al. (2016) with patients diagnosed with schizophrenia. Roberts (1991) examined MiL in a sample of actively psychotic patients with schizophrenia, nurses working at a psychiatric hospital, Anglican priests, and psychiatric patients in remission from active psychosis. This author found that the former scored higher in MiL than all the other subsamples and suggested an interesting hypothesis: the formation of delusions in patients with schizophrenia might provide them with a strong, although non-reality-based, sense of MiL. By their part, Fervaha et al. (2016) found that young people with schizophrenia endorsed significantly lower levels of subjective well-being and happiness than healthy controls, although there was substantial overlap in scores, and many participants with schizophrenia endorsed a high level of well-being; likewise, these authors found a marked overlap in individual scores in happiness between those with and without schizophrenia, demonstrating that many young people with schizophrenia do, in fact, endorse high levels of subjective well-being.

Several studies suggest that MiL might play a positive role in therapeutic interventions in people diagnosed with mental disorders or who suffer emotional dysregulation. For example, MiL buffers the association between risk factors for suicide and hopelessness among patients with mental disorders (Marco et al., 2016), and on the relationship between emotional dysregulation and hopelessness among adolescents (García-Alandete et al., 2019). Moreover, the pursuit and attainment of significant life goals (e.g., in goal-oriented treatment programs) are successful managing of mental disorders and positively influencing the therapeutic process (Sivaraman, 2003). Therefore, it is important to include MiL in assessment and interventions for people diagnosed with mental disorders.

The studies above suggest that: (1) only a few studies have analyzed the differences in MiL according to the diagnosis in people with mental disorders; (2) MiL is expressed at a different level in different mental disorders; (3) the symptomatology might provide people with schizophrenia-spectrum and eating disorders a source of MiL, although non-reality based and dysfunctional, by which they score higher in MiL than those diagnosed with depressive disorders. Taking this into account, better understanding the differences in MiL based on the diagnosis might improve the assessment, treatment, prognosis, and prevention of symptomatology and frequent negative behaviors among people with mental disorders (such as self-injuries, suicide, and hopelessness) (e.g., Marco et al., 2014; Marco, Guillen et al., 2017).

The present study aimed to analyze the differences between people diagnosed with schizophrenia-spectrum, eating, anxiety, and major depressive disorders according to the diagnosis. We hypothesized that (1) both the schizophrenia-spectrum disorder and eating disorder subsamples will show higher scores in MiL than both the anxiety and major depression disorders subsamples and that (2) the major depressive disorder subsample will show the lowest score in MiL.

The present study’s findings highlight the importance of considering MiL in people with mental disorders, and they can stimulate further research on this issue for better understanding the way MiL is experienced and how it can be improved in patients with mental disorders.

The schizophrenia-spectrum disorder subsample showed the highest score in MiL, M = 48.35, SD = 15.28, followed by the eating disorder subsample, M = 46.08, SD = 9.63, the anxiety disorder subsample, M = 36.64, SD = 12.19, and the major depressive disorder subsample, M = 31.17, SD = 13.66. There was a significant effect of diagnosis in MiL, F_{(4, 192)} = 27.08, p = 0.000, h² = 0.371, after controlling for the effects of gender, F_{(1, 192)} = 2.34, p = 0.128, age, F_{(1, 192)} = 0.58, p = 0.447, and length of evolution, F_{(1, 192)} = 0.29, p = 0.589.

The Bonferroni test showed significant differences (1) between the schizophrenia-spectrum disorder subsample and both the major depressive and anxiety disorders subsamples, and (2) between the eating disorder subsample and both the major depressive and anxiety disorders subsamples (Table 2).

Table 2 Table 2 Multiple comparisons for differences in MiL according to diagnosis

Note. Based on the estimated marginal means.

The purpose of the present study was to analyze the differences in MiL between people without a diagnosis of mental disorder and patients diagnosed with schizophrenia-spectrum, eating, anxiety, and major depressive disorders. We hypothesized that: (1) both the schizophrenia-spectrum and eating disorders subsamples would show higher scores in MiL than both the anxiety and major depressive disorders subsamples; (2) the major depressive disorder subsample would show the lowest scores in MiL.

Hypothesis 1: Both the schizophrenia-spectrum and eating disorders subsamples would show higher scores in MiL than both the anxiety and major depressive disorders subsamples

Both the schizophrenic-spectrum disorder and eating disorder subsamples scored significantly higher in MiL than the other subsamples. The means difference between the schizophrenic-spectrum disorder and the eating disorder subsamples was not significant. The means differences between both the schizophrenic-spectrum disorder subsample and eating disorder subsample and both the anxiety disorder and major depressive disorder subsamples were significant. In contrast, the means difference between the anxiety and major depressive disorder subsamples was not significant.

Regarding the differences between the schizophrenic-spectrum disorder subsample and both the anxiety disorder and major depressive disorder subsamples, previous studies found higher scores in MiL in schizophrenic patients than those with anxiety and depressive disorders, as well as higher scores on quality of life (Saarni et al., 2006) and positive life satisfaction, even though their educational, psychosocial, functioning conditions, social life, and work were more deteriorated than patients with depression, lack of social support, and low economic status (Koivumaa-Honkanen et al., 1996). It is worth noting that both quality of life and life satisfaction are positively related to MiL (Martela & Steger, 2016). The relationship between schizophrenia-spectrum disorder and MiL might be mediated by other variables, such as social support (care of family and friendships) (e.g., Lan & Su, 2007), affective (positive emotional experiences) (e.g., Koivumaa-Honkanen et al., 1999), or even spiritual (e.g., Rosmarin & Koenig, 2020), among others, that might offer resources for coping with the mental disorder. On the other hand, as noted above, the formation of delusions might provide a strong, although non-reality-based, sense of MiL in patients with schizophrenia, especially in psychotic phases (Roberts, 1991). Likewise, it must be noted that the schizophrenia-spectrum disorder subsample in the present study was composed of long-term patients in an outpatient social-rehabilitation unit, where they participated in subsample-therapy, social skills, and daily-skills subsamples, which were a strong resource to help them in their lives. This very close level of support may make them feel that their lives, despite their diagnosis, are worth living. In this regard, Stolovy et al. (2009) concluded that the caring that inpatients with schizophrenia received within the hospital provided them with a kind of community where they felt they belonged and found MiL.

Regarding the eating disorder subsample, D’Abundo and Chally (2004) found in a qualitative study that women with eating disorders experienced a false sense of control by not eating, and Fox and Leung (2009) suggested that eating disorder symptoms function as a source of MiL in anorexic patients, providing the patient with a sense of control and a sense of uniqueness with which to address negative states. Sense of control and uniqueness, although dysfunctional, might prevent people with eating disorders from being aware of their disorder, thus allowing them to feel optimistic about their daily lives, which might explain the higher score in MiL in the eating disorder subsample than in both the major depressive and anxiety disorder subsamples.

Hypothesis 2: The major depressive disorder subsample would show the lowest score in MiL

The major depressive disorder subsample scored lower in MiL than all the other subsamples, although the difference with the anxiety disorder subsample was not significant. The sense of lack of control and self-determination, lack of vital interests and goals, hopelessness, a negative and pessimistic attitude toward life, and emotional suffering, which are stronger among people with major depressive disorder than among people with other mental disorders, might explain the lower scores of the former in MiL (e.g., Sacco & Beck, 1995).

As noted above, the differences were significant with both the schizophrenic-spectrum disorder and eating disorder subsamples. It is widely accepted that mood disorders, such as depression, are common psychiatric comorbidities in people with anxiety disorder. Likewise, most cases of mood disorders-not otherwise specified represent hybrids between mood and anxiety disorders, such as mixed anxiety-depressive disorder (e.g., Williams et al., 2007). The common comorbidity between depression and anxiety (e.g., Kelftaras & Katsogianni, 2012) might explain the non-significant differences between the major depressive disorder subsample and the anxiety disorder subsample in the present study. This result suggests some reflections considering previous studies whose results contradicted those obtained in the present study. For example, Volkert et al. (2014) found that patients with depression scored lower in MiL than patients with anxiety disorders, among others, stating that this result seems meaningful, considering that loss of interest and hopelessness are part of the diagnostic criteria for depression. In another vein, Seow et al. (2016) found non-significant differences between patients with depression and patients with anxiety disorders in general coping, spirituality, interpersonal skills, personal growth, and autonomy (which are domains of positive mental health related to MiL), but significant differences in emotional support, as patients with anxiety disorders scored higher than those with depression. These results and those obtained in the present study suggest that differences in levels of hopelessness might explain why people with anxiety disorders score higher in MiL than people with major depressive disorder: hopelessness might mediate the relationship between MiL and both anxiety and major depressive disorder.

On the other hand, in the present study, other variables such as social support, spirituality, and treatment, among other variables that could influence participants’ MiL, were not included. These issues should be taken into account in future research in people diagnosed with mental disorders.

MiL is not only significantly related to positive mental health, but it can even be a strong resource for coping with mental disorders. Several studies suggest that having significant life goals might influence the motivation to be actively involved in the therapeutic process (Sivaraman, 2003) and be crucial in understanding the etiology and recovery from mental disorders (e.g., Fulford et al., 2020). MiL might buffer the relationship between risk factors for suicide and hopelessness in mental disorders (Marco et al., 2016); the dysfunctional sense of control in people with mental disorders might be redirected within a “circle of acceptance” toward an authentic sense of MiL that leads to recovery (D’Abundo & Chally, 2004). Therefore, MiL should be included in both assessment and psychotherapeutic intervention for people with mental disorders by considering how MiL is expressed in each. Empowering patients to discover a personal source of MiL and involve them in setting their own life purposes and goals should be an important goal in mental disorder treatment and recovery. On the other hand, MiL might increase during interventions with people with mental disorders (e.g., Kelftaras & Katsogianni, 2012). Therefore, there could be an effect of reciprocal feedback between MiL and psychotherapy in people with mental disorders.

In this regard, Meaning-Centered Therapy in combination with Cognitive-Behavioral Therapy (Ameli, 2016), Dialectic-Behavioral Therapy (Lungu & Linehan, 2017), and Acceptance and Commitment Therapy (Moghbel & Haghayegh, 2019), among others, might be a helpful resource. This type of therapy can introduce issues related to life satisfaction and setting significant life goals to improve the intervention, thus contributing to managing symptoms and behaviors caused by the mental disorder, facing life challenges (e.g., stressful life events), and having a fulfilling life, even when one has a mental disorder (Volkert et al., 2014).

An important limitation of the present study was the small subsamples size and their unbalanced composition in age and gender. Although it is common to use small and unbalanced sample sizes in studies with clinical samples (e.g., Schulenberg et al., 2011; Volkert et al., 2014), future research should use subsamples with sufficiently large and more balanced sample sizes to carry out comparative analyses in better conditions. In the same way, future research should include patients with different mental disorders from those used in the present study to better understand how MiL is expressed.

Because MiL might mediate the relationship between mental disorders and clinically relevant behaviors, such as substance abuse, self-injurious behaviors, and suicide (e.g., Marco et al., 2019), and it might predict treatment outcome (e.g., Glaw et al., 2017), it would be relevant to assess its role in the relationships among mental disorders, relevant behaviors, and therapeutic intervention (e.g. Marco et al., 2020).

In addition, it would be interesting to analyze the role played by psychosocial (such as gender, religiosity/spirituality, social support, marital status, and quality of life, among others) and clinical (such as symptomatologic phenomenology of the different mental disorders, the severity of symptoms, use of psychiatric medication, and attending social-rehabilitation units, among others) variables in the relationship between mental disorders and MiL. Likewise, future studies should explore whether people with mental disorders attending different types of medical or psychosocial resources differ in their levels of MiL.