There has been a longstanding debate as to whether depression, which is noted exceedingly frequently in MS patients, is caused by the disease state (in other words biologically distinct from depression that occurs in other neurologic and psychiatric conditions) or is a co-morbidity of MS (meaning that MS and depression tend to occur together but one does not cause the other).
There has been a great deal of data (epidemiologic, neuroimaging, neuroimmunologic, and treatment-based) that suggests that depression is a core manifestation of MS. The difficulty is that the many different symptoms of MS occur in many different medical conditions and so why treat the symptom of depression differently. For example, visual changes, tingling, motor findings and incontinence can have many different causes other than MS but clinicians do not challenge that when they occur in an MS patient they are evidence of disease progression.
Depression can be defined by sadness. Yet, the degree of depression can affect how it is experienced. When depression is more severe, there are other symptoms besides sadness, such as decreased concentration, “pseudo”-dementia, sleep disturbances, among others. One reason to believe that there is a causal relationship of MS and depression is that epidemiological studies show MS patients are more likely to have these more severe symptoms than healthy age- and sex-matched comparisons.
Some neuroimaging studies are showing a relationship between MRI changes and depression but certainly not with the distinct observable lesions associated with other MS symptoms, such as optic neuritis.
The answer likely lies in between. Increased disease burden as seen on MRI scans argues that the damage to brain tissue is manifested as depression. At the same time, having MS and the potential impact on one’s future is likely to cause depression, just as loss of a loved one or of a job could.
The best approach is to reassess MS treatments when depression worsens to optimize prevention of progression while at the same time addressing the depression with counseling and medication as appropriate.
The BeCare MS app can assist you by monitoring not only your physical changes, but also changes in your mood and evidence for depression.
Reference: https://journals.sagepub.com/doi/10.1177/13524585241245653