Delusional belief about location ("reduplicative paramnesia").

Introduction: People admitted to hospital as inpatients following head injury or stroke sometimes form the delusional belief that they are located somewhere else-often, near or in their home. This delusion was first described by Pick, who named it "reduplicative paramnesia"; we argue instead for the term "location delusion".

Methods: We carried out a literature search and identified 112 cases of location delusion published since Pick's original 1903 case.

Results: We found that, in this cohort of patients, the belief about being located elsewhere than the hospital is elaborated into more specific delusional beliefs about just where the patient is located (e.g., beliefs that involve mislocation of the hospital). We identified eight specific location beliefs and offered a two-factor motivational explanation of these eight forms of location delusion. The patient wishes to be somewhere more congenial, that wish becomes a hypothesis (as occurs in normal belief formation), and then, because these patients have impaired ability to evaluate hypotheses, the hypothesis is accepted and maintained as a (delusional) belief.

Conclusion: Our previous papers on the two-factor theory of delusional belief focussed on fully neuropsychological delusions. Here we propose that this theory can also explain delusions generated by motivational influences.