Inclusion Criteria:  Diagnosis of idiopathic normal pressure hydrocephalus according to international guidelines Age ≥ 50 years and ≤ 82 years Cognitive function with Mini-Mental State Examination > 20 points MRI image characteristic of normal pressure hydrocephalus, defined as callosal angle < 90 degrees, tight high convexity, dilated Sylvian fissures, and presence of periventricular white matter hyperintensities Signed informed consent form  Exclusion Criteria:  Exclusion criteria for MRI examination Participation in another medical trial Other disease likely to impact the symptoms of the patient Wheelchair user or unable to walk without support Reduced kidney function with GFR < 50 Reduced liver function (increased INR or alanine transaminase concentrations in plasma) Known heart failure Low concentrations of electrolytes in blood plasma that, according to the investigator, prevents participation in the study Angle-closure glaucoma Allergy to acetazolamide, sulfonamides, or sulfonamide derivatives Treatment with phenytoin, valproate, carbamazepine, lithium, oral anticoagulants, thiazide-diuretics, or acetylsalicylic acid > 100 mg/day Inability to swallow capsules of the same size as the investigational medicinal products (will be tested using empty capsules when the patient is asked to participate in the study) Average walking time for the three walking tests < 11 seconds Average walking time for the three walking tests > 50 seconds Inability to comply with the study treatment independently, and a concurrent lack of individuals to help the patient comply with the treatment during the study period Fertile woman without highly effective contraception. A Fertile woman will be tested with pregnancy test before inclusion is possible.