Schizophrenia has been linked to genetic and environmental risk factors. Agerbo and coauthors studied 866 patients with schizophrenia and 871 matched control participants to assess the contribution of the following 3 etiological factors: polygenic risk score, parental socioeconomic status, and family psychiatric history. Schizophrenia was robustly associated with all 3 factors and family history was partly mediated through the polygenic risk score.
Neuroticism is a well-known risk factor for psychiatric illness. A large data set from the Genetics of Personality Consortium was used to study the genetic variants associated with neuroticism. A genome-wide significant single-nucleotide polymorphism on chromosome 3 in the MAGI1 gene was discovered and neuroticism was found to be influenced by many genetic variants of small effect.
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White matter abnormalities are common in schizophrenia but their clinical significance remains unknown. Sun and coauthors examined diffusion tensor imaging data from 113 medication-naive patients with first-episode schizophrenia and 110 matched control participants and used a hierarchical clustering algorithm to identify patterns of abnormal white matter integrity. They identified the following 2 subgroups of patients: one with widespread abnormalities and more severe negative symptoms (42.5% of patients) and another with abnormalities restricted to the superior longitudinal fasciculus, a major white matter tract connecting prefrontal and parietal cortical regions.
Survey studies have found that psychotic experiences are surprisingly common in otherwise healthy individuals; however, little is known about the detailed epidemiology of such experiences. Using data from the World Health Organization World Mental Health Surveys in 18 countries around the world, McGrath and coauthors presented information on characteristics of psychosis and the individuals who experience psychosis. They reported a mean lifetime psychotic experience prevalence of 5.8%, which were more often hallucinations compared with delusions. These experiences were more common in middle- and high-income countries, women, and nonmarried unemployed individuals.
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Perceived racial discrimination greatly increases risk for multiple mental disorders but it is unknown if this relationship is mediated by the following 2 underlying transdiagnostic factors: internalizing and externalizing. Rodriguez-Seijas and coauthors used data from the National Survey of American Life to assess 12 common psychiatric diagnoses and their relationships to transdiagnostic factors in a nationally representative sample of 5191 African American adults. Perceived racial discrimination was not associated directly with a specific diagnosis but instead with internalizing and externalizing behaviors in vulnerable individuals, which were expressed as psychiatric syndromes.
Highlights. JAMA Psychiatry. 2015;72(7):629. doi:10.1001/jamapsychiatry.2014.1894