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Neuromelanin-sensitive MRI can measure dopamine function linked with schizophrenia

Study findings revealed that neuromelanin-sensitive MRI may be a marker of dopamine function and an indicator of psychotic symptom severity in people with schizophrenia.

It’s important to measure dopamine activity to better understand how it affects neurodevelopment, cognition and neuropsychiatric disease, according to Clifford M. Cassidy, PhD, from New York State Psychiatric Institute, Columbia University Medical Center, and the University of Ottawa Institute of Mental Health Research, and colleagues.

“In medicine, such measurements may result in objective biomarkers that predict clinical outcomes in dopamine-related illness, including Parkinson’s disease and psychotic disorders, ideally by using techniques that capture the underlying pathophysiology while being easy to acquire in clinical settings,” they wrote in Proceedings of the National Academy of Sciences.

The researchers conducted a series of validation studies to determine whether neuromelanin-sensitive MRI — which detects the content of neuromelanin, a product of dopamine metabolism that accumulates with age in dopamine neurons of the substantia nigra — can be a biomarker of dopamine function in people without neurodegenerative disorders. They also evaluated the connection between neuromelanin-sensitive MRI (NM-MRI) signal and psychosis severity.

Cassidy and colleagues found that higher NM-MRI signal was linked to higher concentrations of neuromelanin across all sections of post-mortem brain tissue, which confirms the ability of NM-MRI to measure regional concentrations of neuromelanin, according to the release.

Additionally, the researchers validated a voxelwise NM-MRI approach to determine substantia nigra subregions. Using this approach along with molecular PET and functional MRI data, they further exhibited that NM-MRI was associated with dopamine release in the dorsal striatum and resting blood flow within the substantia nigra.

When examining the link between NM-MRI signal and psychosis severity, the investigators found that more severe psychosis symptoms correlated to higher NM-MRI signals in the nigrostriatal pathway of people with and at risk for schizophrenia, according to the release. These findings indicate that NM-MRI can capture dopamine dysfunction, which may support the use of NM-MRI as a biomarker for psychosis.

"The main advantages of this technique are that, compared to other established and more direct measures of dopamine function, neuromelanin-sensitive MRI does not involve radiation or invasive procedures," author Guillermo Horga, MD, PhD, of Columbia University, said in the press release. "This advantage makes it more suitable for pediatric populations and for repeated scanning, which could be useful to monitor the progression of illness or response to treatment — and it only takes a short scan that could be implemented in most clinical scanners.” – by Savannah Demko

Disclosures: Cassidy and Horga report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.