On occasions, patients may report memories of events that never happened in their lives, for example, they may claim with conviction to have been in a place before, or lived through a particular experience, or carried out a deed. During the second half of the nineteenth century, these clinical phenomena were conceived of as a form of memory disorder. Changes in the definition of memory occurred during the 1880s, and this, inter alia, led to their eventual neglect. But they are still met with in clinical practice and need to be discussed in a book on the neuropsychiatry of memory complaints. Since most of the interesting clinical descriptions are to be found in earlier publications, this chapter will perforce have a historical flavour.

In 1886, Emil Kraepelin suggested that the term ‘paramnesias’ might be used to refer to the qualitative disturbances of memory whose study, as opposed to quantitative memory disturbances (general and partial amnesias and hypermnesias), had been confined to a few case reports. Such reports most commonly referred to what Walter Scott called ‘sentiment of pre-existence’ (and Feuchtersleben called ‘phantasm of memory’, and the French déjà vu) and featured prominently in the medical work of Wigan, Jensen, Jackson, Sander, Pick and Anjel. But whilst the former three writers conceived of this phenomenon as a ‘disturbance of perception’ (resulting from a lack of synchrony between the two hemispheres), Sander and Pick proposed that it was a disturbance of memory.