Australian researchers on Friday said they have found important links between brain hyperactivity and hallucinations in people suffering from a major age-related blindness, a discovery that could improve the way the mental experiences are diagnosed.
The link between patients of the macular degeneration eye disease and abnormally heightened activity in the brain's visual cortex, which processes visual information, could help reduce any misdiagnosis of hallucinations, the Queensland Brain Institute said in a statement about its research on Friday.
Researchers stimulated the peripheral visual fields of study participants and found that those experiencing hallucinations showed significantly heightened activity in particular parts of their body's visual system.
While the eye disease patients who experience hallucinations demonstrated the hyperactivity, the translation of that behavior into hallucinations was not automatic and is dependent on external triggers which are still not known, said the research report's first author David Painter.
"Sometimes people have these hallucinations when they're in periods of low sensory stimulation, such as in low-light or periods of inactivity, but for others it can be triggered by things such as car rides or television - it varies for the individual," he said.
"What our results say is that the brains of those reporting hallucinations are more excitable, but it still remains unclear how that excitability is then translated into hallucinations - that's a question for future research."
The findings, which were published in scientific journal Current Biology, could help reduce misdiagnosis of hallucinations in people with macular degeneration, said the institute.
Macular degeneration causes progressive deterioration of the central region of the eye's retina, leading to visual loss in the center field of vision, while peripheral vision usually remains unaffected. In Australia, the condition is the leading cause of legal blindness in people aged over 40, according to the institute.
"When people get older and they start having these unusual experiences, they are often worried that something is wrong with them, such as dementia or something similar, so they tend to not report the hallucinations for fear they may be treated differently," said Painter
"Once people realize it's not a brain disorder as such, they tend to have a neutral or even positive experience of their hallucinations."