Diana Perkins, M.D., M.P.H., of the University of North Carolina and colleagues assessed whether polygenic risk scores (PRS) could be used as part of a clinical assessment of schizophrenia risk. A PRS reflects how many individual genetic variants associated with schizophrenia a person has; the higher an individual’s PRS, the greater his or her genetic risk of developing schizophrenia. They looked at health data from 764 young adults (average age 18) considered at high risk for developing psychosis. These young adults were participants in the North American Prodrome Longitudinal Study (NAPLS 2). As part of the NAPLS 2, these individuals were prospectively followed for two years to identify traits that might help predict the onset of schizophrenia.
On the basis of NAPLS 2 data, the researchers developed a risk calculator that was able to predict which high-risk youth might develop schizophrenia with about 70% accuracy. The risk calculator included variables such as age, history of trauma and stressful life events, family history of psychotic disorders, the degree of disordered thoughts, and performance on tasks assessing verbal learning and information processing speed.
The NAPLS 2 participants also provided blood samples, and Perkins and colleagues used these to extract DNA and compute PRS scores for each participant. They found that PRS scores by themselves could predict schizophrenia onset with about 62% accuracy in Europeans and 57% accuracy in non-Europeans. When added to the risk calculator, however, PRS improved the accuracy of these tools.
“Use of a schizophrenia PRS in clinical practice hinges on improved accuracy, especially in persons of non-European ancestry, and [genetic studies] that include individuals from diverse populations are essential,” Perkins and colleagues wrote. “With further improvements and given the relatively low cost and wide availability of genotyping, potential applications of the genetic risk scores to individualized psychosis risk screening warrant further investigation,” they concluded.
For related information on predicting patients most likely to develop psychosis, see the Psychiatric News article “Imaging Advances Could Aid Prediction of Outcome in High-Risk Patients.”