By Eleanor McDermid, Senior medwireNews Reporter
Physicians should be sure to exclude bipolar disorder before prescribing antidepressants to patients with multiple sclerosis (MS) who have depression, say researchers.
The team, led by Mauro Carta (University of Cagliari, Italy), found an increased prevalence of mood disorders among MS patients, with the relative increase largest for bipolar disorders.
Given that it can be hard to differentiate bipolar disorder, particularly type II, from major depressive disorder, the findings imply a risk for overlooking bipolarity in MS patients, say the researchers. This could lead to inappropriate treatment with antidepressants rather than mood stabilizers.
In all, 46.7% of 201 MS patients had any form of mood disorder, compared with just 5.2% of 804 age- and gender-matched controls. Major depressive disorder was most common, occurring in 26.3% of patients versus 4.6% of controls. Bipolar I disorder occurred in 0.99% versus 0% and bipolar II disorder in 7.50% versus 0.25%.
Specific disorders were based on DSM-IV criteria, but the same pattern was apparent with mood spectrum disorders detected with the broader Mood Disorder Questionnaire criteria. Overall, 27.3% of patients versus 4.9% of controls had a depressive spectrum disorder, and 9.9% versus 0.3% had a bipolar spectrum disorder.
“From a clinical perspective, we can consider that the higher risk of suicidality in MS patients could be related to possible mood episodes (included bipolar depression),” writes the team in the Journal of Affective Disorders.
Although less common than depression overall, bipolar disorder was a relatively more frequent mood disorder among the patients than controls. For each control with a bipolar spectrum disorder, 18 had a depressive condition, whereas there were just 2.8 depressive spectrum cases per bipolar case among the MS patients.
“The evidence of a strict association between MS and [bipolar disorder] is really interesting from both a clinical and a pathophysiological point of view,” say Carta et al.
Pathologic processes occurring in MS, such as oxidative stress, may mediate the link between the two conditions, they suggest.
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