Monday June 24, 2019

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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hallucinations
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

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.

ALSO READ: Food Preservative Shows Promise In Schizophrenia Treatment

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)

Next Story

Daily Cannabis Use May Increase Risk of Psychosis

This increased to five times more likely for daily use of high potency cannabis

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cannabis flower marijuana

Amid growing decriminalisation of cannabis use, a new study warns that daily cannabis use, especially of high potency, is strongly linked to the risk of developing psychosis, a mental disorder characterised by a disconnection from reality.

The findings, published in the journal the Lancet Psychiatry, are consistent with previous studies showing smoking pot with a high concentration of THC — over 10 per cent of the psychoactive substance within cannabis — has more harmful effects on mental health than the use of weaker forms.

“As the legal status of cannabis changes in many countries and states, and as we consider the medicinal properties of some types of cannabis, it is of vital importance that we also consider the potential adverse effects that are associated with daily cannabis use, especially of high potency varieties,” said lead author of the study Marta Di Forti from King’s College London.

The new study looked at 11 sites across Europe and Brazil. First, the researchers estimated the prevalence of psychosis by identifying individuals with first episode of psychosis, presented to mental health services between 2010 and 2015.

Marijuana, Canada, israel
In this July 12, 2018 file photo, a newly-transplanted cannabis cuttings grow in pots at a medical marijuana cultivation facility in Massachusetts. (VOA)

Second, they compared 901 patients with first episode of psychosis with 1,237 healthy matched controls to understand the risk factors associated with psychosis.

The researchers collected information about participants’ history of cannabis use and other recreational drugs.

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Across the 11 sites, people who used cannabis on a daily basis were three times more likely to have a diagnosis of first episode psychosis, compared with people who had never used cannabis, the findings showed.

This increased to five times more likely for daily use of high potency cannabis. (IANS)