Overcoming familiarity illusions in a single case with persistent déjà vu

ABSTRACT

While occasional déjà vu is benign in the general population, rare neuropsychological cases with persistent déjà vu have been described in the literature. We report the case of MN, a 25-year-old woman, who suffered a cerebral haemorrhage in the right thalamo-callosal region and experienced recurrent déjà vu episodes. Through clinical interviews and memory tasks related to déjà vu, we assumed that source memory errors and an inappropriate feeling of familiarity (measured by the number of false recognitions) were critically involved in MN’s déjà vu. Based on this, we developed the first neuropsychological intervention dedicated to déjà vu. The rationale was to train MN to detect elements that could produce an inappropriate feeling of familiarity and to promote metacognitive awareness about déjà vu. This intervention was effective at reducing the frequency of déjà vu episodes in MN’s daily life, as well as the number of false recognitions in memory tasks. In addition to its clinical contribution, this single-case study contributes to the limited literature on patients whose déjà vu is not related to epileptic abnormalities and medial temporal brain damage, and provide supportive evidence of the role of an erroneous feeling of familiarity and of metacognitive processes in déjà vu.

KEYWORDS:

• Déjà vu
• familiarity
• recognition memory
• metacognition
• neuropsychological rehabilitation

Acknowledgements

We wish to thank MN for her time and involvement in this study, without which this case report would not have been possible. AE is supported by a Marie Curie COFUND postdoctoral grant from the European Union and the University of Liège. We thank Chris Moulin for his valuable comments on the manuscript. We also thank Marie Geurten for her advice about statistical analysis and Hedwige Dehon for the DRM task.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 However, it is worth mentioning that the medial temporal lobe damage and source memory accounts are not mutually exclusive explanations of the déjà vu phenomenon. In fact, source memory processing is closely linked to medial temporal lobe activity in both clinical and healthy populations (Davachi, Mitchell, & Wagner, 2003; Gold et al., 2006).

2 It should be noted, however, that sensitivity to similarity was a variable that was worked on assiduously with MN throughout the déjà vu intervention. Our results are therefore compatible with this theory.