I read your question and I understand your concern. Patients with advanced dementia often have hallucinations and agitation as part of the clinical picture. Risperidone is usually given precisely to control these phenomena (it does nothing for Alzheimer s disease itself, only alleviates these symptoms). So the symptoms which up to now were controlled by Risperidone have surfaced. It is not so much an withdrawal symptom, but no more drug effect. Seroquel should have a similar efficacy to Risperidone, with some differences in side effects. Perhaps a change in dosage could be considered or if even switch back to Risperidone if there wasn t a specific reason to interrupt it, talk to your doctor about that. I hope to have been of help.