Anxiety is more important than depression in MS - Commentary.

In this issue, the monthly Controversies series addresses the interesting topic of whether anxiety is more important than depression in multiple sclerosis (MS). The opponent teams, namely, Morrow[1] on one side and Turner and Alschuler[2] on the other side convincingly argue that both depression and anxiety have a huge impact on the lives of persons with multiple sclerosis (PwMS). However, the question whether one is more important than the other may be rather hard to answer with certainty. The issue can be approached in different ways, including a quantitative and a qualitative manner.

In the literature, consistent high prevalence rates of depression and anxiety among PwMS have been reported. A recent systematic literature review and meta-analysis reported prevalence rates of 31% (depression) and 22% (anxiety), respectively.[3] Due to the high degree of heterogeneity among the different studies, the prevalence rates varied considerably. This variation can partly be explained by different methodological approaches, for example, differences in sample sizes, recruitment resources, and diagnostic criteria which have been used, that is, based on self-report questionnaires or a disorder confirmed by a clinician. Therefore, it is uncertain if the reported difference in prevalence is significant and clinical relevant.

As clearly stated by Morrow, anxiety may be less recognized and has been less studied as compared to depression in MS. This may distort the comparison between depression and anxiety. Since anxiety seems to be often overlooked in MS, underreporting may result in missing the diagnosis and the opportunity to treat these symptoms with medication or psychotherapy.[4]

Studies have shown that depression and anxiety are associated in MS, and they predict each other in both directions.[5] As reported by the opponent authors, anxiety and depression in MS are both associated with less adherence to medication and non-pharmacological therapies, increased risk of relapses, cognitive impairment, increased use of health care resources, mortality, fatigue, pain, as well as alcohol and other substance abuse. This all may contribute to less quality of life and less stable disease course of MS. Since both depression and anxiety are treatable, recognizing these conditions in PwMS is important.

To answer the question of whether anxiety or depression is more important in MS, we first need to better agree on the definitions for anxiety and depression to be used in MS. Besides this, robust prevalence rates of anxiety and depression in MS should be reliably determined in a population-based cohort of PwMS and the effects on outcomes measures should then be studied. Although MS is an incurable disease, there is an increasing number of disease-modifying treatments available. It is important to detect and treat anxiety and depression. Apart from its direct amelioration, this may also result in an increased treatment adherence and thus a more stable disease course and eventually a better quality of life for PwMS.