Confabulation in Alzheimer's disease and amnesia: a qualitative account and a new taxonomy.

Clinical and experimental observation have shown that patients who confabulate, especially but not exclusively when provoked by specific questions, retrieve personal habits, repeated events or over-learned information and mistake them for actually experienced, specific, unique events. Accordingly, the aim of this study is to characterize and quantify the relative contribution of this type of confabulation, which we refer to as Habits Confabulation (HC), to confabulations produced by 10 mild Alzheimer's disease (AD) patients and 8 confabulating amnesics (CA) of various etiologies. On the Confabulation Battery (Dalla Barba, 1993a, Dalla Barba & Decaix, 2009), a set of questions involving the retrieval of various kinds of semantic and episodic information, patients produced a total of 424 confabulation. HC accounted for 42% and 62% of confabulations in AD patients and CA, respectively. This result indicates that, regardless the clinical diagnosis, the brain pathology or their lesion's site, confabulation largely reflects the individuals' tendency to consider habits, routines, and over-learned information as unique episodes. These results are discussed in the framework of the Memory Consciousness and Temporality Theory (Dalla Barba, 2002).