Schizophrenia patients who experience recurrent hallucinations may also suffer from structural irregularities in a particular region of their brain, according to a new study featured in the journal Nature Communications.

Researchers from the University of Cambridge, Durham University, Trinity College Dublin and Macquarie University have discovered that schizophrenics who also experience hallucinations are likely to have reduced lengths in the folds of their brain known as paracingulate sulcus (PCS).

This irregularity, however, is not present in the PCS of healthy individuals as well as people who suffer from the condition and do not hallucinate.

Paracingulate Sulcus

The paracingulate sulcus is one of the structural folds of the brain that develops before birth. The size of the PCS varies in every individual.

An earlier study conducted by Cambridge researchers found that varying lengths of PCS in healthy people was associated with the process called reality monitoring. This is the ability of a person to correctly differentiate real information from those that are only imagined.

Dr. Jon Simons, the lead investigator of the previous study, once again carried out an examination on the PCS of the brain with a focus on its impact on people with schizophrenia.

Simons and his fellow researchers analyzed the MRI scans of 153 schizophrenia patients and compared them with those of control participants, with emphasis placed on measuring the PCS length in the brain of each participant.

The goal of the recent study is to determine whether the length of the PCS is connected with a tendency to experience hallucinations.

Occurrence of Hallucinations

The researchers discovered that a one-centimeter (0.4-inch) reduction in the size of the paracingulate sulcus in people with schizophrenia corresponded to an increased likelihood of experiencing hallucinations by as much as 20 percent.

This occurrence was seen in patients regardless of whether the hallucinations were visual or auditory in nature.

According to Simons, schizophrenia can be defined as complex range of conditions associated with various differences throughout a person's brain. This makes it difficult for researchers to identify specific connections between areas of the brain and symptoms typically observed in patients.

He added that by studying structural differences between schizophrenia patients with and without the experience of hallucinations, they were able to determine a specific region of the brain linked to a symptom of schizophrenia.

The researchers note that developments in other brain areas could also have an impact in triggering hallucinations, such as regions responsible for processing auditory and visual information.

Individuals who suffer from hallucinations may perceive information incorrectly because the process of reality monitoring for regions surrounding the PCS are likely affected by changes in their brain.

"We think that the PCS is involved in brain networks that help us recognize information that has been generated ourselves," Dr. Jane Garrison, one of the authors of the study, said.

"People with a shorter PCS seem less able to distinguish the origin of such information, and appear more likely to experience it as having been generated externally."

Garrison pointed out that hallucinations are quite complex and are indicative of mental illness. These occurrences, however, are also common across the general population in various forms.

While it is likely that there is more than one explanation as to why hallucinations occur, Garrison said the result of their study shows how some individuals experience things that do not actually exist.

Photo: Allan Ajifo | Flickr