<qa>  How many subjects will take sertraline?. Subjects: One hundred people will take part in this study: approximately 50 subjects will take sertraline and 50 will take placebo. These patients will be selected from referrals to the Defense and Veterans Head Injury Program at WRAMC. Patients will be active duty or other military beneficiaries, between 18 and 65 years of age. Males and non-pregnant females may participate. 