More than one- third of people with severe head injury will have significant, permanent memory impairments, according to the U.S. Centers for Disease Control and Prevention (CDC). The agency also reports that in the United States alone, some 1.4 million people sustain a traumatic brain injury every year. In addition, about 10 percent of people over age 65 have dementia, usually with memory impairment, according to neuropsychologist Barbara Wilson, PhD, of the U.K. Medical Research Council and The Oliver Zangwill Centre for Neuropsychological Rehabilitation. Memory problems are also seen with multiple sclerosis, AIDS, encephalitis, temporal-lobe epilepsy and Korsakoff's syndrome (associated with alcoholism) and can show up after stroke, brain tumor, myocardial infarction, meningitis and oxygen deprivation.

--R. ADELSON