Is it Depression? Atypical Presentation of Mood Disorders in Multiple Sclerosis
The clinical presentation of psychiatric disorders in the setting of neurological illnesses may differ from the classic presentation of primary psychiatric disorders. Patients with Multiple Sclerosis (MS) and depression may present an increased prevalence of irritability, cognitive disturbances, and other symptoms compared to patients with Major Depressive Disorder and no neurological illness. In addition, non- depressed patients with MS frequently present symptoms of fatigue and cognitive and sleep disturbances, that may mimic depression. These factors may misguide clinicians and cause patients to receive an inadequate diagnosis and treatment.
To examine the frequency of fatigue, sleep disturbances, subjective cognitive complaints, irritability, impulsivity, and affect disturbances in patients with MS referred to a psychiatric evaluation and their relationship with these patients' psychiatric diagnoses.
50 patients with MS referred to psychiatric evaluation were examined on the Patient Health Questionnaire-9 (PHQ-9), the Generalized Anxiety Disorder 7-item scale (GAD-7), the Center for Neurologic Study-Lability Scale (CNS-LS) for pseudobulbar affect, the Mood Disorder Questionnaire (MDQ), and the Modified Fatigue Impact Scale (MIFS).
Symptoms of fatigue, sleep disturbances, and subjective cognitive complaints were highly prevalent in these patients, both in cases clinically assessed as presenting a depressive syndrome and those without this diagnosis. A subset of patients presented a high PHQ-9 score, but did not present clinical depression. A significant proportion of patients reported isolated symptoms of Bipolar Disorder and Pseudobulbar Affect without meeting clinical criteria for these two entities.
The clinical presentation of psychiatric disorders in MS may differ from that of primary psychiatric disorders. Screening tools and formal assessment instruments may be helpful to identify the presence of symptoms in a systematic way, but clinical correlation is needed to reach an accurate diagnosis and for the adequate management of these patients.