Mianserin, a 5-HT2 receptor antagonist, in the treatment of delirium: an open study

To determine the role of the serotonin system at the 5-HT2 receptors on delirium in the aged, we assessed the effects of mianserin, a relatively selective 5-HT2 receptor antagonist, in such patients. Twenty-six delirious patients [four without dementia, nine with Alzheimer's disease (AD), 13 with ischemic vascular dementia (IVD)] were included in the open study. After the dose titration period, the mean dose of mianserin administrated was 31.2 mg in delirious patients without dementia, 25.0 mg in delirious patient with AD and 25.9 mg in delirious patients with IVD. The average total score of each patient group on a symptom rating scale was reduced significantly within 24 h (p < 0.05). A complete elimination of symptoms was noted in all four delirious patients without dementia. In the nine delirious patients with AD, marked improvement was noted in four patients (44.4%), moderate improvement in four (44.4%) and no improvement in one (11.1%). In the 13 delirious patients with IVD marked improvement was noted in seven (53.8%), moderate improvement in five (38.5%) and no improvement in one (7.7%). The rapidity of the improvement may be attributable to mianserin's antagonism at the 5-HT2 receptors, and such serotonin antagonism at the 5-HT2 receptors may be important in treating delirium.-