Mood disorders in multiple sclerosis and the effects on cognition

Background: Depression and cognitive dysfunction are common in patients with multiple sclerosis. However, it is unclear whether depression may cause or exacerbate cognitive problems as data remain equivocal. The current review attempts to clarify the relationship between these behavioral disorders. Method: The literature pertaining to the influence of depression on cognition in MS patients has been reviewed. Results: Early studies consistently failed to find an association and concluded that cognitive dysfunction in MS patients occurred independently of depression. A more recent literature has found fault with this, citing numerous methodological flaws in the studies undertaken. Newer data now suggests that core symptoms of depression reduce cognitive capacity, in particular exerting an adverse effect on the executive function component of working memory. Conclusions: Depression may exacerbate cognitive dysfunction in MS patients. Whether treating depression will lead to cognitive improvement is not yet known, but warrants further exploration. (c) 2006 Elsevier B.V All rights reserved.