Patients with higher myasthenia gravis (MG) disease severity scores also have higher rates of anxiety and depression, likely because of the disease’s impact on daily life rather than a genetic connection, suggests a study recently published in Frontiers in Neurology.
The analysis found that 62.5% of patients with MG experienced anxiety and 46.9% had depression, with risks increasing alongside physical severity and daily activity limitations.
The clinical portion of the study included 96 patients newly diagnosed with MG at a medical center in China; 34 patients had generalized MG and 62 had ocular MG, with a mean age of 51.6 years. To ensure the findings specifically reflected the impact of the disease, the study excluded anyone with a history of psychiatric conditions prior to their MG diagnosis.
To quantify severity, researchers used the Quantitative Myasthenia Gravis (QMG) scale, where higher scores reflect greater muscle weakness, and the MG Activities of Daily Living (MG-ADL) scale, where higher scores indicate more severe impairment in daily tasks.
For each one-point increase in the QMG score, the risk of anxiety rose by 11.9% and depression by 15.7%. Each one-point increase in the MG-ADL score was associated with a 22.5% increase in anxiety risk and an 18.5% increase in depression risk.
Findings showed that emotional distress was closely tied to current symptoms rather than how long a patient had been diagnosed. Variables such as age, sex and the use of corticosteroid treatments did not significantly influence these mental health outcomes.
To investigate whether the link was genetic, the team used Mendelian randomization. This method uses inherited variants as a “natural experiment” to determine if one condition directly causes another at a biological level, independent of environmental factors.
The analysis found no evidence of a direct genetic link between MG and mental health issues. Furthermore, a “reverse” analysis showed that an inherited predisposition to anxiety or depression does not increase the risk of developing MG.
Read more about MG causes and risk factors
“These findings suggest that more severe MG symptoms and reduced quality of life are more likely to be accompanied by anxiety and depression,” the authors wrote.
The researchers concluded that the connection between MG and mental health observed in clinics is likely a response to the psychological toll of the condition. They noted that the study’s limitations include a small clinical sample size and a genetic dataset primarily limited to individuals of European ancestry.
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