Neurological disorders are diseases that affect the central nervous system (brain and spinal cord) and nerves of the peripheral nervous system. Symptoms can include pins and needles, loss of sensation, paralysis, muscle weakness, seizures, pain, fatigue, cognitive decline, and memory loss. Of the more than 500 different types of neurological disorders, scientists at San Diego BioMed, focus on multiple sclerosis, vascular dementia, and HIV-associate neurocognitive disorders.