Myasthenia gravis is a chronic disease in which antibodies are directed against the neuromuscular junction, causing fluctuating muscle weakness. Patients with myasthenia gravis tend to report poor quality of life, even while on treatment.
The disease burden of myasthenia gravis often extends to patients’ mental health. “Central fatigue is a prevalent patient-reported symptom in myasthenia gravis,” Ruiter and colleagues wrote in Neuromuscular Disorders. “Concomitant depressive disorders are frequent and it has a negative impact on quality of life in several studies.”
Fatigue is one of the most commonly reported symptoms of myasthenia gravis. It can be broadly categorized into two types: peripheral fatigue and central fatigue. While peripheral fatigue is often the result of neuromuscular junction failure, central fatigue is a perceived lack of energy that might be physical or mental in origin.
The Impact of Fatigue
Fatigue is a vague clinical presentation; it can occur in patients with no detectable pathology. Part of the difficulty of fatigue as a symptom is that it exists on a spectrum; there is no clear line that delineates what constitutes normal tiredness vs fatigue requiring medical attention. In addition, some question the evidence of the association between myasthenia gravis and fatigue.
Read more about myasthenia gravis etiology
In a study published in the Journal of Clinical Neuromuscular Disease, Yang and colleagues sought to explore the relationship between myasthenia gravis and common symptoms such as fatigue and sleep quality. They recruited self-identified myasthenia gravis patients and requested that they fill in a few questionnaires regarding fatigue and sleep quality. The research team also conducted telephone interviews with the recruited participants.
The results demonstrated that patients with myasthenia gravis scored poorly in the questionnaires on fatigue and sleep quality. Yang and colleagues concluded, “There is a moderate positive correlation between various [myasthenia gravis]-specific outcome measures and fatigue severity.”
Fatigue can also trigger a cascade of limitations that further increases disease severity. For example, studies have demonstrated that strenuous physical activity is negatively correlated with fatigue. This is regrettable, considering that moderate physical exercise has been shown to improve fatigability.
The Prevalence of Depression
Ruiter and colleagues conducted a study on the impact of myasthenia gravis on depressive symptoms. They discovered that symptoms of fatigue and depression often overlap; for example, a patient might report “feeling weak”, which can be true both physically and mentally. This also demonstrates the difficulty in discerning which symptom came first, ie, fatigue or depression, since one can cause the other and vice versa.
Ruiter and colleagues also discovered a difference in coping strategies between patients who reported feelings of fatigue vs patients who did not. This is a novel finding that is highly nuanced; it suggests that psychiatric support may improve clinical outcomes. A common mental health exercise that focuses on coping strategies is cognitive behavioral therapy. This form of therapy may be suitable for helping patients overcome negative thoughts and emotions. By identifying how patients with myasthenia gravis cope with their disease, physicians are better able to tailor treatment to meet individual needs.
Read more about myasthenia gravis complications
As published in the World Journal of Psychiatry, Yu and colleagues conducted a study to investigate the relationship between the clinical features of late-onset myasthenia gravis and mental health. They theorized that the duration of the disease and its severity contribute to increased rates of depression.
The research team recruited patients with myasthenia gravis and categorized them according to their age at disease onset (early onset: less than 50 years; late onset: 50 years or more). The participants were asked to fill in questionnaires relating to activities of daily living, quality of life, and anxiety.
The results demonstrated that patients’ perception of their quality of life was significantly associated with depression. In addition, the researchers also discovered that women were more susceptible to anxiety and depression and that there was a correlation between age and a deterioration in quality of life parameters.
What could explain the higher prevalence of mental illness among female patients compared to men? The authors of the study wrote that glucocorticoids can result in “changes in physical appearances, leading to conditions such as moon face and/or central obesity, which may have greater negative sociopsychological effects on women with [myasthenia gravis] than men.” In addition, female patients with late-onset myasthenia gravis tend to experience comorbidities for a longer period of time compared to men.
The reasons why patients with myasthenia gravis tend to grapple with mental illness are multifactorial and complex. However, simply understanding the scope of the problem might help physicians look beyond physical symptoms and to see their impact on mental health. Only then can we meaningfully empower our patients to live happier, more hopeful lives.
References
Yu L, Qiu L, Ran H, Ma Q, Lu YR, Liu WB. Studying the relationship between clinical features and mental health among late-onset myasthenia gravis patients. World J Psychiatry. 2022;12(3):470-482. doi:10.5498/wjp.v12.i3.470
Ruiter AM, Verschuuren JJGM, Tannemaat MR. Prevalence and associated factors of fatigue in autoimmune myasthenia gravis. Neuromuscul Disord. 2021;31(7):612-621. doi:10.1016/j.nmd.2021.04.002
Yang S, Miglis MG, Jaradeh S, Muppidi S. Myasthenia symptom burden, fatigue, and sleep: are they related? J Clin Neuromuscul Dis. 2021;22(3):123-128. doi:10.1097/CND.0000000000000321
