AMSTERDAM – Neurometabolite deficiencies in the dorsolateral prefrontal cortex may contribute to the lack of insight people with severe mental illness have into their condition, a study showed.
Previous studies have shown that insight lives in the prefrontal cortex, which also is involved in cognitive flexibility and executive function, two other functions often impaired in severe mental illness. Previous studies also have shown a relationship between psychosis and reduced N-acetylaspartate (NAA) in the prefrontal cortex, which is thought to indicate impaired brain function or damage.
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Daouia Larabi, a researcher and PhD candidate at the University of Groningen (the Netherlands), and her colleagues administered the Birchwood Insight Scale (BIS) and the Positive and Negative Syndrome Scale (PANSS) to 80 adult patients with severe mental illness to determine their levels of insight into their illness. The results were then correlated with those from each individual participant’s NAA tests done with an imaging technique called proton magnetic resonance spectroscopy, which measures neurometabolite levels and their ratio to creatine in the white matter of the brain, specifically the dorsolateral prefrontal cortex. Illness duration, use of antipsychotics, gray matter content, and cerebrospinal fluid content were covariates.
Ms. Larabi and her colleagues found that patients with poorer insight as scored on the PANSS also had significantly lower levels of NAA in the prefrontal cortex (P = .045), although the investigators did not find a significant correlation between insight and other neurometabolites such as glutamate in the same region of the brain. There also was a significant positive correlation between NAA to creatine levels and the BIS scores (P = .004). Both results indicate that reductions in NAA were associated with poorer insight, Ms. Larabi said at the annual congress of the European Congress of Neuropsychopharmacology.
Daouia Larabi
Although she said this is the first study to show an association between decreased NAA concentrations and impaired insight, the study still does not offer any conclusions about whether one causes the other. However, because poor insight has been linked to treatment nonadherence and more hospitalizations in the severely mentally ill, the findings are exciting, according to Dr. Andreas Meyer-Lindenberg, editor-in-chief of the journal European Neuropsychopharmacology.
“Insight is highly relevant for the prognosis of people with schizophrenia and psychosis, and linking it to dysfunction in a specific brain system, if replicated, may point to new therapeutic or diagnostic approaches in the future,” Dr. Meyer-Lindenberg said in a statement.
Ms. Larabi said she had no conflicts to disclose.
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