Subjects will undergo 4 high-resolution MP-RAGE scans: once each at Baseline, 2 months, 6 months and 12 months. Scheduled Participants will be randomized 1:1 to citalopram or placebo. We will follow a standard approach to flexible dosing with citalopram as recommended by the manufacturer, initiating treatment with a dose of 20 mg (two capsules) daily. Clinicians may increase or decrease the dose by one capsule every two weeks to a maximum of 4 capsules and a minimum of one capsule daily.