Abstract
Depressive disorders (DDs) are relatively common in most major neurologic disorders, including epilepsy, stroke, dementias, Parkinson's disease, and multiple sclerosis. These DDs have a negative impact on the course and response to therapy of the neurologic disorder. Yet, DDs remain underrecognized and undertreated. The use of screening instruments can help overcome this major problem. However, caution must be exerted in the interpretation of instruments developed for primary DDs, as several somatic and cognitive symptoms that are common in primary DDs may be the expression of symptoms of the neurologic disorder or of adverse events of pharmacotherapy. Furthermore, DDs associated with some neurologic disorders may differ in their semiology. Thus, it is desirable to have depression scales validated for each neurologic disorder. Fortunately, most instruments appear to yield comparable acceptable sensitivities and specificities.