Researchers have identified the neuromelanin-sensitive magnetic resonance imaging (NM-MRI) scan as a potential biomarker for psychosis. NM-MRI signal is a marker of dopamine function in people with schizophrenia and an indicator of the severity of psychotic symptoms.
Disturbances affecting dopamine are associated with a number of mental and neurological disorders, such as schizophrenia and Parkinson’s disease (PD). Dopamine’s role in these disorders means that measuring its activity is vital for increasing our understanding of the disorders and how to best diagnose and treat them, say the researchers.
Neuromelanin is a dark pigment in the dopamine neurons of the midbrain, especially the substantia nigra, which has a role in reward and movement. Neuromelanin accumulates over the lifespan and is only removed from cells after cell death in neurodegenerative disorders like Parkinson’s disease.
Although NM-MRI proved useful in detecting neuron loss in neurodegenerative illnesses, it had not previously been shown to provide a marker of dopamine function, nor had its utility been demonstrated in people without such illnesses. The current study showed that NM-MRI can serve as a marker of dopamine function in individuals without neurodegenerative disorders.
An advantage of the technique is that NM-MRIs don’t involve radiation or invasive procedures and require only a short scan. This makes them more suitable for pediatric populations and for repeated scanning, which could be helpful for monitoring the progression of illness or response to treatment.
The researchers examined the link between NM-MRI signal and psychosis severity and found that more severe symptoms were associated with higher NM-MRI signals in individuals with schizophrenia and in those at risk for schizophrenia. Their findings suggest that NM-MRI captures the dopamine dysfunction, supporting NM-MRI’s role as a potential biomarker for psychosis.
Future study will likely aim to detect abnormalities in the neuromelanin signal that would help predict who is most likely to develop a psychotic disorder in individuals with early symptoms of psychosis.
Source: National Institutes of Health, February 19, 2019