Although constipation is often difficult to treat because it is part of Parkinson’s disease, there are many ways to try it, such as eating a high-fiber diet (many benefit from linseed), but then it is also important to get at least 1.5 liters of fluid per day. Motion can also help. Bulk remedies (and dietary fiber) can be tricky to use just because constipation can get worse if you don’t drink enough. Have you tried medications like Movicol?