Case 1—A 79 year old man with Parkinson's disease, chronic obstructive pulmonary disease, peptic ulcer disease, and irritable bladder was seen regularly in the clinic for Parkinson's disease at this hospital. He was taking selegiline, co-beneldopa, ranitidine, theophylline, intermittent courses of prednisolone, and inhaled beclomethasone dipropionate and salbutamol. In May 1994 he developed mild cognitive impairment. Selegiline was discontinued; this resulted in a noticeable improvement. His score in the abbreviated mental test was 9/10. Later that year he started taking oxybutynin (2.5 mg three times a day) for his urinary symptoms. …