Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. His dementia s purely because of the fall that he had. Taking his age into consideration it is difficult to treat the short term memory loss caused due to his fall and head injury. T.Lyrica that he is on is Pregabalin which protects from seizures and decreases neurological pain. T.ativan which has been prescribed to him his actually a Benzodiazepam which can cause confusion, specially in the elderly. Its important you take him to your psychiatrist or physician at the earliest. As of now it is important to stop T.Ativan, I m sure that will improve the confusion part. Kindly do this at the earliest and let me know. Hope I have answered your query. Let me know if I can assist you further.