Visual hallucinations in synucleinopathies
- 1Department of Neuroscience, Imaging and Clinical Sciences, G. d'Annunzio University of Chieti and Pescara, Italy
- 2Aging Sciences and Translational Medicine Center (CeSI-MeT), Italy
- 3Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, United States
Synucleinopathies include Parkinson’s disease and Dementia with Lewy Bodies, where visual hallucina-tions (VH) are so frequent to lead to the conclusions that if hallucinations do not appear during the dis-ease course, diagnosis should be challenged. VH may be early and simple and late and complex, includ-ing hallucinatory states which represent an unmet need for treatment. Our review analyses old and re-cent hypotheses on the mechanisms of VH and discusses a number of drugs involved in production and suppression the VH, in order to complete the hypothesis of mechanisms. Recent models of VH are cen-tered on decoupling of the Default Mode Network (DMN), which is released in these disorders from the fronto-parietal control and from salience networks, resulting in perception of priors stored in uncon-scious memory. The release of DMN supposedly releases the intrinsic narrative of DMN. The thalamus represents a powerful control relay according to recent theories on “cognitive thalamus”. The networks involved imply practically all relevant neurotransmitters, including glutamic acid, Gamma-Aminobutyric Acid (GABA), dopamine, serotonin, acetylcholine. Actually, evidence-based medicine can only rely on clozapine, an old drug very effective but burdened by several side effects. According to the models, serotonergic, glutamatergic, GABAergic and dopaminergic pathways should be investigated in order to develop possible new treatment drugs. According to a possible model of thalamic dysfunction, also drug acting on calcium channels might find a role. Our review analyses also the agonist and antagonist drugs and reports on drugs inducing hallucinations as side effects, which should be taken into account when managing hallucinating disorders in these patients, who are also carriers of many comorbidities.
Keywords: Visual hallucinations in synucleinopathies , Dementia with Lewy body (DLB), Parkinson’s disease, default mode network (DMN), synucleinopathies
Received: 21 Jun 2019;
Accepted: 30 Oct 2019.
Copyright: © 2019 Russo, Carrarini, Dono, Rispoli, Di Pietro, Di Stefano, Ferri, Bonanni, Sensi and Onofrj. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: MD. Marco Onofrj, Department of Neuroscience, Imaging and Clinical Sciences, G. d'Annunzio University of Chieti and Pescara, Chieti, Italy, email@example.com