The Neurobiological Mechanism for Hallucinations and Delusions

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A new study¹ from researchers at Columbia University Vagelos College of Physicians and Surgeons may have discovered a link between hallucinations/delusions and psychosis, thereby explaining their clinical presentation. 

Researchers collected data from 127 patients diagnosed with schizophrenia from online databases to study the neurobiological mechanisms of hallucinations and delusions. Kenneth Wengler, PhD, Guillermo Horga, MD, PhD, and colleagues discovered that neural timelines in the lower levels of the hierarchal model of psychosis tended to be longer for patients with severe hallucinations, whereas neural timescales in the higher levels of the hierarchal model of psychosis tended to be longer for patients with severe delusions. This discovery is the first piece of direct evidence of a potential neurobiological mechanism for hallucinations and delusions.

“Typically, patients with more severe hallucinations also have more severe delusions, and these two symptoms respond similarly to antipsychotic medications. But this is not always the case; some patients have very prominent hallucinations but less severe delusions and vice versa,” Wengler, a Postdoctoral Research Fellow of Columbia, said to the press. “This suggests that these symptoms may share a common neurobiological mechanism while simultaneously depending on symptom-specific pathways.”²

Using functional magnetic resonance imaging, researchers measured intrinsic neural timescales in the brain to determine whether the mechanisms of hallucinations and delusions function within the hierarchical model. By examining specific regions of the brain, the research team could evaluate whether neural timelines reflected how long information took to integrate.

“Our findings open the door for the development of treatments to target specific symptoms of psychosis depending on an individual subject's symptom profile, in line with the current push for individualized medicine,” Horga, Florence Irving Associate Professor of Psychiatry, said to the press.²

References

1. Wengler K, Goldberg AT, Chahine G, Horga G. Distinct hierarchical alterations of intrinsic neural timescales account for different manifestations of psychosis. eLife. October 27, 2020. https://elifesciences.org/articles/56151​

2. Columbia University Irving Medical Center. Study finds evidence of neurobiological mechanism for hallucinations and delusions. News release. Medical Xpress. November 9, 2020. https://medicalxpress.com/news/2020-11-evidence-neurobiological-mechanism-hallucinations-delusions.html​