Q. A 65-year-old-man is brought to the office by his son because he is worried that his dad has "dementia". Over the past couple of years, the patient has gone from being a busy attorney to not being able to continue at work. It seems that every few months, he "just gets worse" and seems to lose some cognitive ability, including trouble recalling names, losing items, and forgetting appointments, although he has remained "fairly nice mannered" with no major outbursts or personality changes. He also has had episodes where he seems clumsy for a period of weeks with gradual improvement but without total resolution: for instance, he suddenly had trouble with his right hand doing handwriting and picking up utensils and still struggles with it being clumsy, and he suddenly developed difficulty walking and no longer walks more than to the mailbox to get the mail, without a cane. He has smoked 2 packs of cigarettes daily for the past 30 years and he only drinks on rare occasion. His temperature is 36.7, BP is 145/80, and breathing rate is 18/minute. He has a history of hypertension, hypercholesterolemia, and coronary artery disease. On clinical examination, in addition to poor cognitive function, he has asymmetrically brisk and pathologic reflexes on the right side, slowness of fine motor tapping on the right, and a wide-based, unsteady gait. In the right upper extremity, after an initial resistance to passive movement, the tone is suddenly normal and the limb is easily moved. MRI of the brain reveals multiple white matter hyperintensities on T2 and FLAIR images, microbleeds, and enlarged basal ganglia perivascular spaces. What is the most important next step in management?