Delusions are strong false beliefs that persist despite evidence to the contrary. While delusions are associated with neurological or mental illness, they are not tied to any particular disease although they often aid in the diagnosis of schizophrenia, manic episodes of bipolar disorder, and psychotic depression.
New research finds that brain activity increases during delusional thinking, a finding that may allow new interventions and retraining for people with the disorder.
The study, found in the journal Biological Psychiatry, compared brain activity as statements were read to a group of individuals with schizophrenia and to a group without schizophrenia.
“We studied a type of delusion called a delusion of reference, which occurs when people feel that external stimuli such as newspaper articles or strangers’ overheard conversations are about them,” said researcher and neuropsychologist Dr. Mahesh Menon.
Delusions of reference occur in up to two-thirds of people with schizophrenia. “Then they come up with an explanation for this feeling to make sense of it or give it meaning,” Menon said.
Investigators called the study an initial attempt to prove that the overactive firing of dopamine neurons in specific brain regions is involved in converting neutral, external information into personally relevant information among people with schizophrenia.
The neuronal hyperactivity, they surmised, may lead to symptoms of delusions. “We wanted to see if we could find a way to ‘see’ these delusions during magnetic resonance imaging scanning,” said Menon.
A better understanding of the brain activity and thinking patterns leading to delusions could point the way to more focused treatment options, the researchers say.
Researchers studied 14 people with a schizophrenia diagnosis and 15 people in a control group. Sixty statements were read to the participants while they were in an MRI scanner. For each statement, participants were asked whether they felt it was about them.
Twenty statements were specific to each participant, and included details taken from initial screening interviews. The remaining 40 statements were generic, and evenly divided between statements that were neutral (“he collects CDs”) or that had an emotional connotation (“everybody hates her”).
People with schizophrenia and in the comparison group were just as likely to agree that personalized statements were about themselves. However, those with schizophrenia were significantly more likely to say that the generic statements also referred to them.
“The participants with schizophrenia had a harder time telling the difference between personally relevant and non-relevant statements,” said Menon.
Researchers studied brain activity when participants were read a statement. They found that when a statement was personal, specific brain areas “lit up” in the scanner, indicating activity in these areas.
Among those with schizophrenia, this brain activity occurred even when they said “no” to a statement that was not about them, suggesting that they had greater difficulty in distinguishing what was self-relevant to what was not.
The control group, which was more likely to respond “no” to irrelevant statements, showed little brain activity in response to generic statements.
Even when people with schizophrenia agreed a generic statement was not about them, they took longer to respond and the difference in certain brain activity levels was not as great as in the control group.
Additional research is indicated to explore these initial findings. For instance, patients in this study were all taking anti-psychotic medication. Other studies could look at people early in illness who are not on medication, and could also follow people over time, before and after they take medication.