An investigation of visual hallucinosis and visual sensory status in dementia

Alzheimer's disease (AD) is a prevalent, long-term progressive degenerative disorder with great social impact. It is currently thought that, in addition to neurodegeneration, vascular changes also play a role in the pathophysiology of the disease. Visual symptoms are frequent and are an early clinical manifestation; a number of psychophysiologic changes occur in visual function, including visual field defects, abnormal contrast sensitivity, abnormalities in color vision, depth perception deficits, and motion detection abnormalities. These visual changes were initially believed to be solely due to neurodegeneration in the posterior visual pathway. However, evidence from pathology studies in both animal models of AD and humans has demonstrated that neurodegeneration also takes place in the anterior visual pathway, with involvement of the retinal ganglion cells' (RGCs) dendrites, somata, and axons in the optic nerve. These studies additionally showed that patients with AD have changes in retinal and choroidal microvasculature. Pathology findings have been corroborated in in-vivo assessment of the retina and optic nerve head (ONH), as well as the retinal and choroidal vasculature. Optical coherence tomography (OCT) in particular has shown great utility in the assessment of these changes, and it may become a useful tool for early detection and monitoring disease progression in AD. The authors make a review of the current understanding of retinal and choroidal pathological changes in patients with AD, with particular focus on invivo evidence of retinal and choroidal neurodegenerative and microvascular changes using OCT technology.

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“…In addition, more complex visual symptoms may arise early in the history of AD, including visual memory deficits and visual hallucinations [7,8].…”

Section: Visual Changes In Ad Patientsmentioning

confidence: 99%

Alzheimer’s disease: A review of its visual system neuropathology. Optical coherence tomography—a potential role as a study tool in vivo

Cunha

Moura-Coelho

Proença

et al. 2016

Graefes Arch Clin Exp Ophthalmol

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“…Offset is equally sudden. Associations with times of low (as opposed to bright or absent) illumination have been reported in dementia (Murgatroyd & Prettyman 2001) and eye disease (Lalla & Primeau 1993;Teunisse et al 1996), and it seems plausible that hypnagogic and hypnopompic hallucinations may also be occurring at times of low illumination. They more rarely occur with eyes closed (Barnes & David 2001;Melzack 1991;Menon et al 2003;Schultz & Schultz et al 1996;Shiraishi et al 2004;Teunisse et al 1996).…”

Section: Time and Placementioning

confidence: 97%

“…GABA may also be implicated Values are averaged proportions (weighted by sample size) plus or minus 95% CI. Sources: (1) Holroyd et al (2001); (2) Barnes & David (2001); (3) Aarsland et al (2001a); (4) Fenelon et al (2000); (5) Murgatroyd & Prettyman (2001); (6) ffytche & Howard (1999); (7) Brown & Murphy (1992); (8) Ballard et al (2001); (9) Cutting (1997); (10) Santhouse et al (2000); (11) Lindal et al (1994); (12) Lepore (1990); (13) Nesher et al (2001); (14) Deiker & Chambers (1978); (15) Pliskin et al (1996); (16) Teunisse et al (1996); (17) Vaphiades et al (1996); (18) Gauntlett-Gilbert & Kuipers (2003); (19) Soros et al (2003); (20) ; (21) Zarroug (1975); (22) Scott et al (2001); (23) Schulman et al (1967); (24) Needham & Taylor (2000). Both random and systematic biases cannot be excluded at present.…”

Section: Pharmacologically Induced Hallucinationsmentioning

confidence: 99%

“…gov.uk). Holroyd et al (2001); (2) Barnes & David (2001); (3) Aarsland et al (2001a); (4) Fenelon et al (2000); (5) Wilson et al (2000); (6) Holroyd et al (2000); (7) Chapman et al (1999); (8) Ballard et al (1999); (9) Barber et al (1999); (10) Imamura et al (1999); (11) Goetz et al (1998a;1998b); (12) Murgatroyd & Prettyman (2001); (13) Brown & Murphy (1992); (14) Holroyd et al (1992); (15) Ballard et al 1995a;(16) Mori et al (2000); (17) Wesnes et al (2001); (18) Diederich et al (1998); (19) Holroyd & Sheldon-Keller (1995); (20) Ohayon et al (1996); (21) Ohayon (2000); (22) Ostling & Skoog (2002); (23) Pliskin et al (1996); (24) ; (25) Morrison et al (2002); (26) Menon et al (2003); (27) O'Reilly & Chamberlaine (1996); (28) Shiraishi et al (2004); (29) Teunisse et al (1998,1999); (30) Scott et al (2001); (31) Teunisse et al (1995) Sources are a mixture of quantitative and qualitative descriptions. nhs.uk); delirium (22% [www.psych.org] of 9.6 million hospital inpatients, prorated from England figures; www.doh.gov.uk); repeated non-pathological day time (0.57% of population), hypnagogic (1.7%) and hypnopompic (0.5%) (Ohayon 2000;Ohayon et al 1996); eye disease (1 million; www.rnib.org.uk); Parkinson's disease (120,000; parkinsons.org.uk); and bereavement (1% of the adu...…”

Section: Phenomenologymentioning

confidence: 99%

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Believing is seeing in schizophrenia: The role of top-down processing

et al. 2005

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The etiology of visual hallucinations is largely undetermined in schizophrenia. Collerton et al.'s PAD model partly concurs with what we know about neurocognition in schizophrenia, but we need to specify the types of perceptual and attentional abnormalities that are implicated in recurrent complex visual hallucinations (RCVH). Available data suggest that abnormal attentional control and top-down processing play a larger role than the ventral stream deficits.

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“…Reduced sensory function is a risk factor for CVH in neurodegenerative illnesses (Ballard et al 2001;Barnes & David 2001;Chapman et al 1999;Holroyd & Sheldon-Keller 1995;Holroyd et al 2001;Murgatroyd & Prettyman 2001), eye disease (Brown & Murphy 1992;Holroyd et al 1992), schizophrenia (Howard et al 1994), and the general population (Ohayon 2000;Ohayon et al 1996). However, further reducing sensory input in hallucinators by closing eyes generally extinguishes, rather than encourages hallucinations (Diederich et al 2003;Kolmel 1993;Menon et al 2003;Santhouse et al 2000;Teunisse et al 1996).…”

Section: Underconstraint and Overconstraint In Psychiatrymentioning

confidence: 99%

Gamma rhythms as liminal operators in sensory processing

Whittington

2004

Behav Brain Sci

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Based on recent insight into the thalamocortical system and its role in perception and conscious experience, a unified pathophysiological framework for hallucinations in neurological and psychiatric conditions is proposed, which integrates previously unrelated neurobiological and psychological findings. Gamma-frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in networks of thalamocortical circuits, thereby transiently forming assemblies of coherent gamma oscillations under constraints of afferent sensory input and prefrontal attentional mechanisms. If perception is based on synchronisation of intrinsic gamma activity in the thalamocortical system, then sensory input to specific thalamic nuclei may merely play a constraining role. Hallucinations can be regarded as underconstrained perceptions that arise when the impact of sensory input on activation of thalamocortical circuits and synchronisation of thalamocortical gamma activity is reduced. In conditions that are accompanied by hallucinations, factors such as cortical hyperexcitability, cortical attentional mechanisms, hyperarousal, increased noise in specific thalamic nuclei, and random sensory input to specific thalamic nuclei may, to a varying degree, contribute to underconstrained activation of thalamocortical circuits. The reticular thalamic nucleus plays an important role in suppressing random activity of relay cells in specific thalamic nuclei, and its dysfunction may be implicated in the biological vulnerability to hallucinations in schizophrenia. Combined with general activation during cholinergic arousal, this leads to excessive disinhibition in specific thalamic nuclei, which may allow cortical attentional mechanisms to recruit thalamic relay cells into resonant assemblies of gamma oscillations, regardless of their actual sensory input, thereby producing an underconstrained perceptual experience.

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An investigation of visual hallucinosis and visual sensory status in dementia

Cited by 30 publications

References 15 publications

Alzheimer’s disease: A review of its visual system neuropathology. Optical coherence tomography—a potential role as a study tool in vivo

Alzheimer’s disease: A review of its visual system neuropathology. Optical coherence tomography—a potential role as a study tool in vivo

Believing is seeing in schizophrenia: The role of top-down processing

Gamma rhythms as liminal operators in sensory processing

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