The study of individuals with damaged memory shows a lot about how a healthy memory works. ‘Memory impairment’ considers the condition of memory loss (amnesia) where memory does not work effectively due to brain injury. How can other clinical conditions and mental states, besides brain damage, influence memory? Different subtypes of amnesia have different characteristics. The study of amnesia is important as a way of discriminating between memory processes and in linking deficits in remembering with specific neurological structures that are damaged. Not all memory disorders arise from organic injury or illness. ‘Psychogenic amnesia’ is usually caused by a functional impairment of memory with no tangible evidence of neurological brain injury.