<qa>  What type of disease may be a cause of a person with a history of?Healthy normal volunteers 18 years of age and older may be eligible for this study. Individuals with a history of neuropsychiatric disorders, brain lesions such as tumors, stroke, or trauma, or a history of significant medical disorders, such as cancer, may not participate. Candidates will be screened with a medical history, brief physical examination, and questionnaire. 