Brain disconnections may contribute to Parkinson's hallucinations

September 27, 2017, Radiological Society of North America
Box-and-whisker plot shows mean functional connectivity in patient groups with Parkinson's disease (PD) and control participants. Patients with PD + visual hallucinations (VH) had significantly lower mean functional connectivity compared with control participants, whereas mean functional connectivity in patients with PD - VH and control participants was not significantly different. Credit: Radiological Society of North America

Researchers have found that disconnections of brain areas involved in attention and visual processing may contribute to visual hallucinations in individuals with Parkinson's disease, according to a new study published online in the journal Radiology. The disconnected brain areas seen on functional MRI (fMRI) may be valuable in predicting the development of visual hallucinations in patients with Parkinson's disease.

Hallucinations are sensations that seem real but are created in a person's mind. A person having a hallucination may see, hear or feel something that is not actually there. According to the National Parkinson Foundation, visual can be a complication of Parkinson's .

"Visual hallucinations in Parkinson's disease are frequent and debilitating," said study author Dagmar H. Hepp, M.D., from the Department of Neurology and the Department of Anatomy and Neurosciences at VU University Medical Center (VUMC) in Amsterdam, the Netherlands. "Our aim was to study the mechanism underlying visual hallucinations in Parkinson's disease, as these symptoms are currently poorly understood."

Studies using fMRI to investigate visual hallucinations in patients with Parkinson's disease are rare and have been mainly limited to task-based methods using activities that involve visual stimulation or cognitive tasks. However, the authors note that the presence of visual hallucinations is strongly linked to the development of cognitive decline in patients with Parkinson's disease. Cognitive deficits may influence a patient's ability to perform specific tasks during an fMRI exam.

MR images show reduced regional functional connectivity in, A, Parkinson's disease (PD) patients and, B, exclusively in PD + visual hallucinations (VH) patients. Regional functional connectivity analysis revealed lower functional connectivity in PD + VH as well as PD - VH patients compared with control participants in paracentral and occipital regions (yellow areas in A; P < .05, corrected for multiple comparisons). Functional connectivity in frontal, temporal, and subcortical regions was exclusively lower in patients with PD + VH compared with control participants (red areas in B; P < .05, corrected for multiple comparisons). Credit: Radiological Society of North America

For this study, researchers used resting-state fMRI to examine the connectivity, or communication, between . Resting-state fMRI is a method of imaging that can be used to evaluate patients not performing an explicit task. The connectivity was measured in 15 patients with visual hallucinations, 40 patients without visual hallucinations, and 15 healthy controls by calculating the level of synchronization between activation patterns of different brain .

The results showed that in all the patients with Parkinson's disease, multiple brain areas communicated less with the rest of the brain as compared to the control group. However, in patients suffering from visual hallucinations, several additional brain areas showed this decreased connectivity with the rest of the brain, especially those important in maintaining attention and processing of visual information.

"We found that the areas in the brain involved in attention and were less connected to the rest of the brain," said study author Menno M. Schoonheim, Ph.D., from the Department of Anatomy and Neurosciences at VUMC. "This suggests that disconnection of these brain areas may contribute to the generation of visual hallucinations in with Parkinson's disease."

While there are no direct therapeutic implications for patient care based on the research, the authors note that future studies could indicate whether techniques that could stimulate the areas with decreased connectivity could be helpful to treat visual hallucinations in people with Parkinson's disease.

Explore further: New concept may explain vision problems in Parkinson's disease

More information: "Loss of Functional Connectivity in Patients with Parkinson Disease and Visual Hallucinations." Radiology (2017).

Related Stories

New concept may explain vision problems in Parkinson's disease

May 6, 2014
(Medical Xpress)—Are patients with Parkinson's disease "blind to blindsight?" That's not a trick question, but the focus of an inquiry by neuroscientists from Rush University Medical Center as well as the Centre Hospitalier ...

Researchers identify visual system changes that may signal Parkinson's disease

July 11, 2017
Changes in the visual systems of newly diagnosed Parkinson's disease patients may provide important biomarkers for the early detection and monitoring of the disease, according to a new study published online in the journal ...

Don't believe your eyes: Team discovers way to induce visual hallucinations

October 24, 2016
Visual hallucinations ... everyone has heard of them, and many people have experienced the sensation of "seeing" something that isn't there. But studying the phenomenon of hallucinations is difficult: they are irregular, ...

Trial helps doctors tell Lewy body dementia from Alzheimer's, Parkinson's

September 21, 2016
Knowing that many clinicians find it difficult to correctly diagnose patients with Lewy body dementia, researchers at The Ohio State University Wexner Medical Center set out to develop a clinical profile for these patients. ...

Breakthrough opens door to study hallucinations scientifically

October 12, 2016
A new method for inducing, modelling and measuring visual hallucinations in healthy individuals suggests these complex experiences share a common underlying mechanism with normal visual perception, UNSW researchers say.

Recommended for you

New wearable brain scanner allows patients to move freely for the first time

March 21, 2018
A new generation of brain scanner, that can be worn like a helmet allowing patients to move naturally whilst being scanned, has been developed by researchers at the Sir Peter Mansfield Imaging Centre, University of Nottingham ...

International team confirms new genetic mutation link to amyotrophic lateral sclerosis

March 21, 2018
Kinesin family member 5A (KIF5A), a gene previously linked to two rare neurodegenerative disorders, has been definitively connected to amyotrophic lateral sclerosis (ALS) by an international team from several of the world's ...

New ALS gene points to common role of cytoskeleton in disease

March 21, 2018
An international team of researchers led by John Landers, PhD, at UMass Medical School, and Bryan Traynor, MD, PhD, at the National Institute on Aging at the National Institutes of Health (NIH), has identified KIF5A as a ...

Neuroscientists develop potential tools for the study of brain function

March 21, 2018
A team of University of Missouri neuroscientists are inching closer to developing the tools needed to decipher the brain. In 2015, the team received a National Science Foundation Early Concept Grant for Exploratory Research ...

Researchers listen for silent seizures with 'brain stethoscope' that turns brain waves into sound

March 21, 2018
When a doctor or nurse suspects something is wrong with a patient's heart, there's a simple way to check: put a stethoscope over the heart and listen to the sounds it makes. Doctors and nurses can use the same diagnostic ...

Amygdala neurons increase as children become adults—except in autism

March 20, 2018
In a striking new finding, researchers at the UC Davis MIND Institute found that typically-developing children gain more neurons in a region of the brain that governs social and emotional behavior, the amygdala, as they become ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.