Depression in multiple sclerosis: a long-term longitudinal study.
BACKGROUND
Depression is a common comorbidity in multiple sclerosis (MS), but little is known about its long-term prognosis. Depression in the general population is usually episodic with relatively short-lasting depressive episodes. In this study we investigate the long-term prognosis of depression in MS.


METHODS
Using data from a large longitudinal observational study and from the Calgary MS clinic database, we investigated changes in Center for Epidemiological Studies Depression Scale (CESD) scores in MS patients over four years of follow-up. We used logistic regression to investigate the association of the factors sex, age, disease duration, Expanded Disability Status Scale (EDSS), depression at baseline, and antidepressant use with depression at each year of follow-up.


RESULTS
CESD scores remained largely stable, or decreased slightly over four years of follow-up, whereas EDSS scores steadily increased. Depression at baseline was the strongest predictor of depression at follow-up; the other factors were not or not consistently associated with depression at follow-up. As expected, antidepressant use was associated with a greater risk of depression at follow-up. Starting and stopping antidepressant treatment during follow-up was not associated with the risk of depression at follow-up or with significant change in CESD scores.


CONCLUSION
In contrast to depression in the general population, depression in MS is largely chronic, which suggests a different pathophysiology.