Tuesday September 25, 2018

Scientists Discover Link Between Hallucinations, Dopamine

The researchers found that elevated dopamine could make some patients rely more on expectations, which could then result in hallucinations

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For the study, published in the journal Current Biology, researchers designed an experiment that induces an auditory illusion in both healthy participants and participants with schizophrenia. Pixabay
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People with schizophrenia, who experience auditory hallucinations, tend to hear what they expect an exaggerated version of a perceptual distortion that is common among other people without hallucinations.

According to the researchers, those with hallucinations and other psychotic symptoms are known to have elevated dopamine — the main area of focus for available treatments for psychosis — but it was unclear how this could lead to hallucinations.

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“Our brain uses prior experiences to generate sensory expectations that help fill in the gaps when sounds or images are distorted or unclear,” said Guillermo Horga, Assistant Professor at Columbia University Medical Centre.

“In individuals with schizophrenia, this process appears to be altered, leading to extreme perceptual distortions, such as hearing voices that are not there,” Horga added.

hallucinations
The researchers found that elevated dopamine could make some patients rely more on expectations, which could then result in hallucinations. Pixabay

They examined how building up or breaking down sensory expectations can modify the strength of this illusion. They also measured dopamine release before and after administering a drug that stimulates the release of dopamine.

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Patients with hallucinations tended to perceive sounds in a way that was more similar to what they had been cued to expect, even when sensory expectations were less reliable and illusions weakened in healthy participants, the researcher said.

This tendency to inflexibly hear what was expected was worsened after giving a dopamine-releasing drug, and more pronounced in participants with elevated dopamine release, and more apparent in participants with a smaller dorsal anterior cingulate — a brain region is previously shown to track reliability of environmental cues).

“All people have some perceptual distortions, but these results suggest that excess dopamine can exacerbate our distorted perceptions,” said Horga. (IANS)

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Extract From Cannabis Can Help Treat Psychosis, says Study

All participants were studied in an MRI scanner while performing a memory task which engages three regions of the brain known to be involved in psychosis

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Cannabis extract may offer treatment for psychosis: Study. Pixabay

A single dose of the non-intoxicating compound of cannabis — cannabidiol — can help reduce brain function abnormalities seen in people with psychosis, results of a clinical trial, led by an Indian-origin doctor, has revealed.

Psychosis is a mental disorder characterised by a disconnection from reality.

Brain activity in the people at risk of psychosis remains abnormal compared to the healthy ones.

But in people who had cannabidiol, the abnormal brain activity was less severe than for those who received a placebo, suggesting cannabidiol can help re-adjust brain activity to normal levels.

The results suggest that cannabidiol may normalise dysfunction in striatum, parahippocampal cortex, and midbrain — brain regions which are critically implicated in psychosis — and this may underlie its therapeutic effects in psychosis, the researchers explained.

Cannabis
Cannabis leaf. Pixabay

“Our results have started unravelling the brain mechanisms of a new drug that works in a completely different way to traditional anti-psychotics,” said Sagnik Bhattacharyya from Britain’s King’s College, London.

For the study, published in JAMA Psychiatry, the team studied a small group of young people who had not yet been diagnosed with psychosis but who were experiencing distressing psychotic symptoms, along with healthy controls.

All participants were studied in an MRI scanner while performing a memory task which engages three regions of the brain known to be involved in psychosis.

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“One of the main advantages of cannabidiol is that it is safe and seems to be very well tolerated, making it, in some ways, an ideal treatment,” Bhattacharyya said.

“If successful, this trial will provide definitive proof of cannabidiol’s role as an antipsychotic treatment and pave the way for use in clinic,” he noted. (IANS)

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