Objective: Study cognitive, behavioral correlates of identity of presence hallucinations in Parkinson’s disease.

Background: Presence hallucination (PH), the sensation that someone is nearby when no one is actually there, is frequent in Parkinson’s disease (PD) and has been linked to negative outcomes such as cognitive decline [1]. Core features of PH are common to most patients and are described as fleeting, of human form, and close to the body. Yet, a subgroup of patients ascribes specific identities to PH (iPH) (e.g., mother) with feelings of familiarity [2]. To date, iPH and its clinical relevance in PD are poorly understood. We compared the sensitivity of PD patients with iPH (PD-iPH) to robotically-induced PH (riPH) and their neuropsychology to that of patients with unidentified PH (PD-uPH) and those without hallucinations (PD-nH).

Method: An interview unveiled 9 PD-iPH, 9 PD-uPH and 25 PD-nH non-demented PD patients. All did a sensorimotor stimulation task able to elicit riPH. Patients moved a robotic device placed in front of them. Another robot behind them reproduced their movements, delivering tactile feedback on their back with varying delays (0-250-500ms). The Parkinson disease cognitive rating scale (PD-CRS) was used to test frontal-subcortical and posterior functioning and UPDRS for severity of PD symptoms.

Results: Patients felt significantly more riPH with increasing delays of asynchrony (p=.01). Both PD-iPH (p=.01) and PD-uPH (p=.04) reported significantly more riPH than PD-nH. PD-iPH and PD-uPH did not differ significantly. PD-iPH scored significantly lower for PD-CRS frontal-subcortical functioning (p=.04) and higher for UPDRS 1 (p<.001), 2 (p<.001) and 4 (p=.01) than PD-nH group. uPH group had significantly higher ratings than PD-nH only for UPDRS 1. No other significant difference was found among groups.

Conclusion: PD-iPH and PD-uPH groups had higher sensitivity to riPH than PD-nH, replicating previous clinical work showing that PD patients with PH have higher sensitivity to the sensorimotor stimulation task, linking PH to altered sensorimotor processing, which is also the case for PD-iPH and PD-uPH groups [3]. PD-iPH had more frontal-subcortical cognitive impairment (though scores were within normal range) than the other groups and more severe impact of PD symptoms in daily life, suggesting that iPH could indicate more rapidly advancing cognitive decline that could lead to dementia.

References: [1] A. Lenka, L. George, S.S. Arumugham, S. Hegde, V. Reddy, N. Kamble, R. Yadav, P.K. Pal, Predictors of onset of psychosis in patients with Parkinson’s disease: Who gets it early?, Parkinsonism Relat. Disord. 44 (2017) 91–94. https://doi.org/10.1016/j.parkreldis.2017.09.015.
[2] G. Fénelon, T. Soulas, L.C. De Langavant, I. Trinkler, A.-C. Bachoud-Lévi, Feeling of presence in Parkinson’s disease, J. Neurol. Neurosurg. Psychiatry. 82 (2011) 1219–1224. https://doi.org/10.1136/jnnp.2010.234799.
[3] F. Bernasconi, E. Blondiaux, J. Potheegadoo, G. Stripeikyte, J. Pagonabarraga, H. Bejr-Kasem, M. Bassolino, M. Akselrod, S. Martinez-Horta, F. Sampedro, M. Hara, J. Horvath, M. Franza, S. Konik, M. Bereau, J.-A. Ghika, P.R. Burkhard, D. Van De Ville, N. Faivre, G. Rognini, P. Krack, J. Kulisevsky, O. Blanke, Robot-induced hallucinations in Parkinson’s disease depend on altered sensorimotor processing in fronto-temporal network, Sci. Transl. Med. 13 (2021). https://doi.org/10.1126/scitranslmed.abc8362.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/exploring-brain-mechanisms-of-identity-attribution-in-presence-hallucinations-of-parkinsonian-origin/