 A randomized placebo controlled clinical trial design will be used to investigate the effectiveness of citalopram in patients with anxiety disorder due to a general medical condition, specifically traumatic brain injury TBI. Beneficiaries who are between 3 and 24 months post injury and who meet criteria for DSM-IV diagnosis of anxiety disorder due to TBI will be recruited from the 7 DVBIC VA and Military Medical Centers. Participants will be randomized to receive an increasing dose of citalopram or placebo up to a dose of 40 mg of citalopram or 4 pills of placebo over a 12-week treatment period. Patients will receive comprehensive multidisciplinary evaluations at a DVBIC site, including neurology, neuropsychology and psychiatry interviews and evaluations at baseline, 12 weeks and 12 months. 