Phantom Boarder Relates to Experimentally‐Induced Presence Hallucinations in Parkinson's Disease

Abstract

BackgroundBackground: Phantom boarder (PB) is the sensation that someone uninvited is in the patient's home despite evidence to the contrary. It is mostly reported by patients with neurodegenerative disorders such as Alzheimer's disease, dementia with Lewy bodies or Parkinson's disease (PD). Presence hallucination (PH) is frequent in neurodegenerative disease, shares several aspects with PB, and is the sensation that someone is nearby, behind or next to the patient (when nobody is actually there). Recent work developed a sensorimotor method to robotically induce PH (robot-induced PH, riPH) and demonstrated that a subgroup of PD patients showed abnormal sensitivity for riPH. Objective Objective: We investigated if PD patients with PB (PD-PB) would (1) show elevated sensitivity for riPH that ( 2) is comparable to that of patients reporting PH, but not PB (PD-PH). Methods Methods: We studied the sensitivity of non-demented PD patients in a sensorimotor stimulation paradigm, during which three groups of patients (PD-PB; PD-PH; PD patients without hallucinations, PD-nPH) were exposed to different conditions of conflicting sensorimotor stimulation. ResultsResults: We show that PD-PB and PD-PH groups had a higher sensitivity to riPH (compared to PD-nPH). PD-PB and PD-PH groups did not differ in riPH sensitivity. Together with interview data, these behavioral data on riPH show that PB is associated with PH, suggesting that both share some underlying brain mechanisms, although interview data also revealed phenomenological differences. Conclusions Conclusions: Because PD-PB patients did not suffer from dementia nor delusions, we argue that these shared mechanisms are of perceptual-hallucinatory nature, involving sensorimotor signals and their integration.Patients with phantom boarder phenomenon (PB) report that someone uninvited has entered or lives in the patient's home, despite of evidence to the contrary. 1 The unsolicited visitor is mostly experienced by patients as an unfamiliar intruder with malevolent intentions (e.g., harm or rob the patient) or hassling behaviors (e.g., make noise), although the visitor may also be experienced as a friend or family member. [1][2][3][4] PB is clinically relevant as it occurs repeatedly, and is a compelling experience, which is often destabilizing for patients, caregivers, and their relationship. Furthermore, PB has been associated with earlier home placement and delirium. 5 PB is prevalent in several neurodegenerative diseases associated with dementia, such as dementia with Lewy bodies (DLB), 6,7 Alzheimer's disease (AD), 8,9 vascular dementia 10 and Parkinson's disease (PD). 6 PB is often described as the most common "delusion" (together with paranoid ideation) in such diseases, with Aarsland et al. 6 reporting PB in 41% of DLB and 17% of PD dementia (PDD) patients.Despite this clinical relevance, understanding of the involved brain mechanisms of PB remains limited and its "exact nosology (…) debatable". 11 In his initial clinical description, Rowan 1 described PB as a delusional ...

Distinct grey and white matter changes are associated with the phenomenology of visual hallucinations in Lewy Body Disease

“…The inferior longitudinal fasciculus is an associative bundle transmitting visual information from occipital areas to the temporal lobe and is involved in visual object recognition and implicated in a several visual perceptual disorders 73 , 74 . The cortico-spinal tract integrity might be consistent with the hypothesis that presence hallucinations can be interpreted as an alteration of self-related sensorimotor processing and this hypothesis has been supported by studies that induced presence hallucinations using a robotic sensorimotor paradigm 59 , 60 .…”

“…Passage hallucinations have been hypothesized to be due to a dysfunction between brainstem eye movement control regions, and subcortical and cortical motion pathways, including dorsal visual stream areas 1 . Presence hallucinations, described as the feeling that someone is close by or has just left the room, have been interpreted as a form of palinopsia relying on dorsal visual stream involvement 1 and recent evidence using a robotic stimulation paradigm suggests they result from sensorimotor conflict 59 , 60 .…”