LEvetiracetam to Prevent Seizures in Symptomatic Alzheimer's Disease in Adults With Down Syndrome

The purpose of this study is to evaluate whether levetiracetam can prevent epileptic seizures in patients with Alzheimer's disease associated with Down syndrome. It will also analyze whether it can delay the neurodegeneration associated with this disease. Patients will be randomly assigned to one of two groups: one group will receive the active drug (levetiracetam), and the other will receive a placebo. Both groups will receive the treatment for 96 weeks. Each patient will participate for a total of 2 years and 5 months.