Most of the published studies assessing the prevalence of psychiatric disorders in multiple sclerosis patients were conducted in the countries of the northern hemisphere (Europe and the USA being the leading centres of research in the field) with a variety of limitations resulting also from the different tools used for analysis of psychiatric diagnosis (validated and non-validated questionnaires, structured interviews, medical records, administrative data) and diverse binding statistical classifications of psychiatric disorders (the International Statistical Classification of Diseases and Related Health Problems, the Diagnostic and Statistical Manual of Mental Disorders, the International Classification of Primary Care) (13). In addition, many of the published systematic reviews focus solely on the incidence and prevalence of depressive and/or anxiety disorders, determining either symptoms (scale studies) or disorders as Axis I diagnoses (35) (19). Few published studies used structured interviews to assess the prevalence of the most common psychiatric disorders in line with the Diagnostic and Statistical Manual of Mental Disorders. De Cerqueira et al. (22) evaluated 60 patients with MS in Brazil using version 5.0 of the Mini International Neuropsychiatric Interview (MINI) for the main diagnoses from the DSM-IV. In regards to affective disorders, the results showed that 36.6% of respondents had depression over the course of their life (18.3% past depressive episode, 18.3% current depression at the time of the study), while 13.3% had bipolar disorder (BD). In regards to anxiety disorders, the most common was generalized anxiety disorder (GAD) diagnosed in 16.7% of respondents, while the second most common was panic disorder (PD) detected in 3.3%. Other disorders from the anxiety axis were absent (22). Our study, by using a very similar study protocol and tools, also confirmed that the mood and anxiety disorders are the most prevalent among MS patients, however we noted a higher percentage of depressive episodes throughout life, a lower percentage of bipolar disorders, as well as a more diverse spectrum of anxiety disorders in comparison to Cerquiera et al. Attention should be paid to the 54% of patients with MS who were simultaneously treated for additional somatic diseases, which could affect the severity and increase the incidence of mental disorders (36).
Because the study concerned patients with changes in the structure of the CNS, the questionnaire method was supplemented by a psychiatric examination, which allowed for the diagnosis of clinical psychopathological symptoms characteristic of organic changes and mood disorders that did not meet the criteria for diagnosis in the MINI questionnaire. Almost the entire study group was diagnosed with demyelinating lesions in the CNS which were revealed through the MRI examination. This is a very important etiological factor that can initiate, exacerbate or sustain the existence of mental disorders (most often cognitive disorders) (37). Other causes of comorbidity of mental disorders include adaptation difficulties related to limitations, symptoms and social problems associated with MS, genetic susceptibility, structural brain abnormalities, the association between depression and immunological and inflammatory changes, drug therapies causing psychiatric disorders, and personality traits that predispose an individual to the occurrence of mental disorders and diseases (38) (13). However, Gasim et al. presented in their work that there is no correlation between MS treatment and an increased risk of psychiatric symptoms caused by disease-modifying therapies (DMT) (39). The conducted psychiatric examinations of the discussed group revealed the occurrence of depressive disorders, detailing depressive episodes or organic mood disorders in 24% of MS patients, anxiety disorders in 11.9%, depressive disorders related to stress in 10.7%, and cognitive disorders in 7.8%. In other studies and reports, cognitive impairment affects 43–70% of the group. The small number of respondents who were found to have cognitive impairment in a psychiatric examination may be associated with the failure to use additional tools and tests to detect cognitive impairment, beyond interview and medical examination; this is one of the important limitations of this work. Reports analyzing the occurrence of mental disorders in MS only on the basis of a medical examination are few and the results obtained correspond to the results of the current work (40).
Galeazzi et al. evaluated 50 patients with relapsing-remitting MS in Italy using the SCID-I to diagnose lifetime and current Axis I psychiatric disorders. In regards to affective disorders, the results showed that 46% of respondents had depression over the course of their life, 6% had bipolar disorders, and 10% had dysthymic disorders. In regards to anxiety disorders, 36% of respondents had any of the anxiety disorders, with simple phobia being the most common (12%) (41). Marrie et al. evaluated 253 patients with MS using the SCID-I to diagnose Axis I Disorders and classified 10.3% as having major depression and 14.6% as having generalized anxiety disorder (42). Antmann et al. evaluated 166 patients with MS to compare self-reported outcome measures in identifying major depression, modifying the SCID telephone interview as a standard, with 29% of respondents meeting the criteria for MDD in terms of the SCID criteria (43). Feinstein et al. examined 100 patients with clinically defined MS attending yearly neurological examinations with the Structured Clinical Interview for DSM-IV and the results obtained showed that 17% of subjects met the criteria for diagnosis of major depression (44). Korostil and Feinstein evaluated 140 patients using the SCID-I to diagnose anxiety disorders, which were determined to be at a level of 35.7% throughout the lifetime of respondents, with generalized anxiety disorder at 18.6%, panic disorder at 10%, and obsessive compulsive disorder at 8.6% (45). Our study is so far the first in Poland to assess the prevalence of psychiatric disorders among MS patients using a structured interview with diagnostic criteria consistent with the DSM-IV. The results obtained seem to follow the general trend observed in other studies, however no statistical significance was observed in comparing the general demographics and clinical characteristics of patients experiencing current and past affective disorders, and affective disorders with coexisting anxiety disorders, in terms of gender, age, duration of the disease, and scoring obtained on the EDSS scale. Sorisoy et al. showed that MS patients with neurological disability and loss of ambulation are more prone to depression, and identified a correlation with EDSS determining degree of disability and depression scores (46). On the other hand, Janssens et al. found that MS patients and their partners continued to have high levels of anxiety and distress in the first years after diagnosis, however there was no correlation with disability (47). Gottberg et al. also published a study proving that patients with depressive symptoms did not perform worse in different aspects of functioning (48).
Suicide risk studied within our group was low among the majority of respondents, while 1.9% of the patients presented a medium risk and 3.9% - a high risk. These results are relatively lower than what has been published by Sorisoy et al. In this sample, 8.3% had a past history of attempted suicide and 8.3% presented a current suicide risk; all patients presenting a current suicide risk had major depression at the time of the interview. (46) Feinstein et al. found a past suicide attempt in 6.4% of the patients interviewed (49). In the Danish group studied by Brønnum-Hansen et al., suicide risk among persons with multiple sclerosis was more than twice that of the general population, with increased risk particularly high during the first year after diagnosis (50). The risk of a suicide attempt in patients with MS is most often the result of the symptoms of depression, which result from the difficulty in coping with the symptoms of the disease, problems in everyday functioning, and lack of support (8) (51). Psychiatric comorbidities may also contribute to maladaptive coping strategies, and poor health behaviors which could alter the course of MS (52).
Lifetime prevalence of psychiatric disorders in the general adult population (aged 18–65) in the European Union countries incl. Norway, Iceland and Switzerland according to the WHO is 25%. 27% had experienced at least one of a series of mental disorders in the past year (this included problems arising from substance use, psychoses, depression, anxiety, and eating disorders) with 1 out of 15 people suffering from major depression, and if all anxiety and different forms of depression are included, 4 out of 15 people (53). Epidemiological studies conducted in Poland in 2015 by Kiejna et al. show that major depressive disorder was found in 3.0% of the population; it was significantly more frequent in women (4.0%) than in men (1.9%). Prevalence in men was not age-related, while in women major depressive disorder occurred significantly more frequently after the age of 50 (5.5%) than in women aged 18–29 (2.7%) and 30–39 (3.3%). Lifetime generalised anxiety disorder was found in 1.1% of the studied population, significantly more often in women (1.5%) than in men (0.6%) (54). This shows that the prevalence of mood and anxiety disorders is significantly higher in Poland than in the general population.
The most important limitations of this work are the small group of respondents with different forms of MS as well as a lack of accurate assessment of the severity of depressive disorders and cognitive impairment. The study did not exclude patients in the condition of exacerbation of the underlying MS disease, which could have influenced the number of patients meeting the criteria for the diagnosis of a specific mental disorder. We also recognize the limitations of this study resulting from data obtained through the MINI while the ICD10 is the most-used classification method in the country and medical records of the patients, along with the clinical psychiatric examination performed, are provided on the basis of the latter. In addition, we are aware of the multilateral model of mental health condition of the MS patients and the need of the more holistic assessment. (55)