Could Psychosis In An Elderly Person Be Due To Reduced Dosage Of Celexa?

at a longterm care facility that I work at as a ADON we had a 90 year old patient on celexa 100mg a day. she has dementia with behaviors. the FNP thought the dose was too high and decreased it to 40mg a day. patient became out of control and was sent out to a local mental facility where she was disgnosed with psychosis. the FNP is now wondering whether she should have left the celexa at the higher dose. your thoughts.