Question What causes constipation in people with Alzheimer's disease? Janice Oklahoma Answer Constipation can occur in people with Alzheimer's disease. But it is most likely due to a side effect of medication or an underlying medical condition such as dehydration — and not due to the Alzheimer's itself. If unrecognized and untreated, constipation can worsen behavioral problems, such as physical aggression, in people with Alzheimer's disease. Ironically, medications used to treat these behavioral problems can worsen constipation. Increasing fluids usually helps relieve constipation. However, frequent and persistent constipation should be evaluated by a doctor. Often, the cause of constipation is treatable. Treatment may include: Increased physical activity Changes in diet Medications to reduce constipation Constipation is a common complication of some other neurological disorders — such as Parkinson's disease and Lewy body dementia — which affect the nerves involved in digestion.