As a chronic neurological condition, it should come as no surprise that multiple sclerosis can produce psychiatric problems. In fact, such psychiatric problems are sometimes even the first presentation of MS. In addition to being an inflammatory, demyelinating disease primarily affecting CNS white matter, it has also been shown to damage cortical gray matter. Unfortunately, this only broadens the kinds of psychiatric and cognitive symptoms such patients can exhibit: “Psychiatric symptoms in MS are highly prevalent and frequently overlooked in clinical settings.12–14 In 1 study of relapsing-remitting patients with MS in remission, 95% reported significant psychiatric symptoms, most frequently dysphoria (79%), agitation (40%), anxiety (40%), and irritability (35%).”
Major depression is particularly common, representing approximately 50 percent of those with MS, as opposed to 10-15 percent of the general population. Those with MS are much more likely to commit suicide than the general population. In one study, depression was found to be more important than both physical and cognitive disability in determining quality of life. Interestingly enough, major depression is more common in those with multiple sclerosis than those with other neurological symptoms. Indeed, depression in MS patients is associated with predictable CNS changes such as lesions in certain parts of the frontal lobe and cortical atrophy. This means that MS cannot likely be explained away as a mere psychological reaction from the difficulties that result from the disorder: “Major depressive disorder in patients with MS, therefore, is unlikely to represent a simple reaction to the physical disability, uncertainty, and decreased independence that the illness entails, but given its prevalence, may be considered a symptom of the illness itself and reflective of CNS cortical damage.”
Major depression is not the only psychiatric symptom associated with MS. Bipolar disorder is twice as common in those with MS than the general population, even when controlling for the mania that can sometimes be precipitated by prednisone treatment. Observe the case of a 41 year old male with MS who was diagnosed with bipolar disorder at this age, following his first manic episode:
“Mr. A’s late onset of manic symptoms would be highly atypical for primary bipolar disorder and suggests that MS lesions in critical brain regions may be a substantial contributing factor to his presentation.21 For example, lesions along the orbitofrontal prefrontal cortex circuit lead to impulsivity, mood lability, and personality changes, symptoms frequently seen in acute mania.8 On the other hand, a history of manic or hypomanic symptoms in Mr. A may have been long overlooked given the complexity of his neurologic and cognitive presentation, leading to a delay in diagnosis of bipolar disorder.”
Pseudobulbar also affects up to 10 percent of those with MS. This produces an asymmetry between mood and affect, such that the individual may have involuntary outbursts of laughing or weeping. “Pseudobulbar affect is common in other neurologic disorders and may be caused by disruption of neuronal connections arising from the brainstem and cerebellum that are involved in regulation of emotional expression.22 Inappropriate episodes of crying and laughing are often embarrassing to patients and may severely limit social interactions.”
Finally, psychosis is 2-3 times higher in those with MS than the general population. “Various MRI studies have demonstrated a high lesion load in the medial temporal regions of the cortex among MS patients with psychosis, again suggestive of a role for demyelinating lesions in critical brain regions in the development of neuropsychiatric symptoms.”
