History repeating itself: Arnaud's case of pathological déjà vu

Déjà vécu with recollective confabulation: an unusual presentation of Alzheimer's disease

A man in his 80s presented with gradual onset of a persistent and delusion-like perception that novel encounters are repetitions of previous experiences. Within 2 years of symptom onset, he had impaired verbal memory and executive dysfunction on neuropsychological assessment. Cerebrospinal fluid core Alzheimer's disease (AD) biomarkers analysis supported probable AD. Generalised and left temporal atrophy was seen on MRI of the brain. Neurological fludeoxyglucose-positron emission tomography (PET)/CT showed left temporal and bilateral frontal lobe hypometabolism. His presenting symptom is known as déjà vécu with recollective confabulation, a rare phenomenon associated with AD and other neurodegenerative disorders. While several potential mechanisms have been previously proposed, the fludeoxyglucose-PET/CT hypometabolism in the temporal and frontal lobes in this case suggests dual deficits in recognition memory and metacognition may be culprit mechanisms. Although uncommon, déjà vécu with recollective confabulation is a fascinating phenomenon that can provide a unique insight into memory and delusional processes in dementia.

Validation Study of Italian Version of Inventory for Déjà Vu Experiences Assessment (I-IDEA): A Screening Tool to Detect Déjà Vu Phenomenon in Italian Healthy Individuals

The Inventory Déjà Vu Experiences Assessment (IDEA) is the only screening instrument proposed to evaluate the Déjà vu (DV) experience. Here, we intended to validate the Italian version of IDEA (I-IDEA) and at the same time to investigate the incidence and subjective qualities of the DV phenomenon in healthy Italian adult individuals on basis of an Italian multicentre observational study. In this study, we report normative data on the I-IDEA, collected on a sample of 542 Italian healthy subjects aging between 18-70 years (average age: 40) with a formal educational from 1-19 years. From September 2013 to March 2016, we recruited 542 healthy volunteers from 10 outpatient neurological clinics in Italy. All participants (i.e., family members of neurological patients enrolled, medical students, physicians) had no neurological or psychiatric illness and gave their informed consent to participate in the study. All subjects enrolled self-administered the questionnaire and they were able to complete I-IDEA test without any support. In total, 396 (73%) of the 542 healthy controls experienced the DV phenomenon. The frequency of DV was inversely related to age as well as to derealisation, jamais vu, precognitive dreams, depersonalization, paranormal activity, remembering dreams, travel frequency, and daydreams (all p < 0.012). The Italian version of IDEA maintains good properties, thus confirming that this instrument is reliable for detecting and characterising the DV phenomenon.