Memory impairment, in which memories formed before the onset of the disease are selectively lost, with the preservation or slight impairment of the ability to remember new information (anterograde memory). Unlike generalized retrograde amnesia, it affects specific periods of life or types of information, leaving other memories intact. Causes can be traumatic brain injury, stroke, brain tumors, or psychological factors; Lesions often affect the temporal or frontal lobes. Recovery can be partial or complete, depending on the cause and severity of the brain damage.