Psychogenic amnesia: when memory complaints are medically unexplained

Amnesia (Fig. 1) has been defined as ‘an abnormal mental state in which memory and learning are affected out of all proportion to other cognitive functions in an otherwise alert and responsive patient’ (Victor 1971). Memory impairment can affect the learning of new material (anterograde amnesia), owing to impairments in the encoding, storage or retrieval stages. It can also affect the recall of previously acquired memories (retrograde amnesia), which might involve personal experiences (episodic memory), general information (semantic memory) or perceptuomotor skills (procedural memory). Psychological factors can cause both anterograde and retrograde memory loss (or a combination of the two).