Degeneration of frontal serotonin-containing neurons occurs in frontal lobe dementia (FLD). The associated loss of serotonin transmission may contribute to the frontal lobe dysfunction associated with this disorder. FLD patients will undergo a controlled clinical trial of an orally administered serotonergic agent (Sertraline) which acts centrally to selectively block serotonin uptake to treat patients' cognitive and behavioral frontal dysfunction. Study subjects will be evaluated at regular intervals with a battery of neuropsychological and behavioral tests designed to assess frontal and other cognitive functions. In addition, compliance and levels of the medication will be measured in the blood and when possible in the cerebrospinal fluid (CSF).