Depressive symptoms and severity of illness in multiple sclerosis: epidemiologic study of a large community sample.
Chwastiak L, Ehde DM, Gibbons LE, Sullivan M, Bowen JD and Kraft GH;
Commented by , 22 Nov 2002
Background
Depression may be more common in Multiple Sclerosis (MS) than in other chronic neurological conditions.
Epidemiologic data, however, have been limited to specialty clinic samples, not necessarily representative of the MS population. The relationship between severity, course, duration of MS and depression is controversial.
Purpose
1) To determine the prevalence of clinically significant depressive symptoms in a large community sample of MS patients.
2) Explore the relationship between depressive symptoms and severity, duration and course of illness.
Method
In a cross-sectional design, all members of a Washington county MS association (n=1374) were mailed a survey, including demographic data, duration and course of illness.
The Expanded Disability Status Scale (EDSS), self-report version, measured severity of MS. The Center for Epidemiologic Studies in Depression (CES-D) Scale, validated in medical settings, evaluated depressive symptoms.
The Modified Social Support Survey assessed social support. Analysis of covariance compared mean CES-D Scale scores across MS categories, and logistic regression identified factors associated with clinically significant depression.
Results
739 respondents yielded a response rate of 53.8%. The sample was predominantly Caucasian and female, with a mean age of 49.3 and illness duration of 12.5 years. 41.8% had clinically significant depressive symptoms (CES-D > or = 16), and 29.1% had moderate to severe depression (CES-D > or = 21). Severity of illness, as per the EDSS, was the most strongly associated factor with depressive symptoms.
Patients with intermediate and advanced illness were 3 and 6 times, respectively, as likely to have CES-D score > or = 16 than patients with minimal disease. Subjects with a shorter duration of MS were more likely to have significant depressive symptoms.
Other factors associated with CES-D score > or = 16 were lower education, younger age and lack of social support. Course of illness was not associated with depressive symptoms.
Discussion
These results confirm that the high prevalence of depression in MS extends beyond a specialty clinic sample. Using the CES-D ³ 16 cut-off, the point prevalence of 42% is much higher than in general (3-9%) and primary care (10-15%) populations, and other chronic medical illnesses such as HIV (21%).
The rate is similar to rates found in Parkinson’s disease, commonly held as the most common CNS disease with comorbid depression.
Given the high prevalence of depression in MS, a suicide rate as high as 15% (1), and newer treatments (e.g interferon) associated with depression (2), screening for depression should be integral to the regular evaluation of MS patients; especially early in the illness course when depression and suicide risk (3) are higher.
In practice, however, the evaluation of disability in MS appears limited to physical symptoms, as evidenced by the EDSS; suggesting a treatable cause of morbidity and mortality may be overlooked. This assertion is supported by the paucity of rigorous treatment studies of depression in MS (4).
Unfortunately, the authors did not address the issue of what proportion of depressed MS patients in this naturalistic setting actually received psychotherapeutic or pharmacotherapeutic treatment.
Data from epidemiologic, genetic and natural history studies have led to debate as to whether depression in MS is the direct result of brain lesions or a psychological response to illness (4). Such causal inferences cannot be drawn from this study, based on the cross-sectional nature of the design.
References
- Sadovnik RB, Eisen K, Ebers GC, Paty DW. Cuase of deaths in patients attending multiple sclerosis clinics. Neurology 1991; 41; 1193-1196
- Neilly LK, Goodin DS, Goodkin DE, Hauser SL. Side-effect profile of interferon beta-1b in MS: results of an open trial. Neurology 1996; 46; 552-554
- Stenager EN, Stenagher E, Koch-Henrikson N, Brønnum-Hansen H, Hyllested K, Jensen K et al. Suicide and multiple sclerosis: an epidemiological investigation. Journal of Neurology, Neurosurgery and Psychiatry 1992; 55; 542-545
- Feinstein A. The clinical neuropsychiatry of multiple sclerosis. Cambridge University Press 1999, Cambridge, UK.