Hi Joe, what dosage of Seroquel have you used in the last 20 years? I have been taking Seroquel 12.5 (half a pill of 25mg) every night, to help me sleep, for the last 1 1/2 years. Last week my PD took me off Seroquel and put me on Mirtazapine7.5 mg. She read some studies that indicate that Seroquel long term leads to Dementia and a propensity for stroke. Mittazapine is not helping me sleep as well as Seroquel did. No withdrawl symptoms form Seriquel yet..