Agitation, aggression, and inappropriate repetitive behaviors are common symptoms of frontotemporal dementia (FTD). These symptoms are distressing to patients and caregivers, often lead to institutionalization, and can be very difficult to treat. Antipsychotic medications are frequently prescribed; however, they often cause side effects including parkinsonism and increased mortality. There is a crucial need to develop new treatments for the behavioral symptoms of FTD. Here Dr. Huey will test the use of low-dose lithium for the treatment of behavioral symptoms in FTD patients. Lithium is a highly effective treatment for agitation in mania. The project is supported by preliminary data in Alzheimer's disease (AD), showing that patients with no or partial response other medications had decreased agitation and aggression with lithium treatment.