Parkinson s is not predominantly a dementia disorder and more of a progressive nervous system disorder affecting moment. Dementia may occur in later stages. If you want to check for dementia or memory tests, multiple online tests are available in relation to Alzheimer s group. If the surgery is being done for parkinsons, then make a list of symptoms patient is experiencing so that parkinsons can be diagnosed properly. Drug interactions are very common so make a list of all medications, vitamins and supplements, patient is taking. Tests are ordered in parkinsons to rule out other causes. Parkinson s diagnosis is based on medical history, symptoms, signs, and a complete neurological examination. Hope I have answered your question. If you have any further query, happy to help again.