ECT as a "therapeutic test" to differentiate pharmaco-resistant depression from dementia in the elderly: a pilot study

Abstract : Objectives. Traditionally, if depression is suspected in elderly patients with cognitive disorders, antidepressant therapy is administered during the first 3 months of diagnosis, in order to treat a comorbid depression that could ultimately compound cognitive impairments. However, antidepressants are only effective in 50 to 60% of such cases, and their use in elderly populations should be restricted due to their potential negative side effects. In order to offer an alternative treatment strategy, we describe several cases here where electroconvulsive therapy (ECT) was used as a "therapeutic test" for the presence of depression. Methods. Eight patients with a diagnosis of « probable dementia; depression remains to be eliminated » were included in the present study. Following a negative "antidepressant test", an "ECT test" was performed. Results. Five patients recovered satisfactorily from depression and cognitive impairments. This improvement persisted for 14 months after the final ECT session. Conclusions. Our results suggest that ECT could be used as a potential therapeutic test in elderly subjects with cognitive impairments when depression is suspected.