Hello, dementia is a chronic condition that impairs the functional capacity of the patient, causing memory loss and other deficits as the disease progresses. I can t - obviously - explain your father s condition without having examined him but I m sure the neurologist is more than capable to handle such situations. After dementia becomes evident, you can t expect a great improvement and you can t expect him to get back to normal. The drugs are supposed to improve his functional status but they won t make him normal. Despite that, you should discuss how he s going with the neurologist. The neurologist should re-assess your father and perhaps modify his treatment regimen. Kind Regards!