Genes that confer schizophrenia vulnerability were linked to reductions in white matter integrity, suggesting that genes responsible for brain structural development overlap with schizophrenia genes, according to Marc M. Bohlken and his associates.
For the study, 70 individual twins genetically vulnerable to schizophrenia were compared with 130 control patients. Lower global fractional anisotropy (FA) was correlated with schizophrenia liability (phenotypic correlation: –0.25). Just over 8% of global FA genetic variation was shared with schizophrenia vulnerability, with network connections in the frontal, striatal, and thalamic regions the most affected areas.
Further analysis showed that global FA contributed independently to schizophrenia vulnerability, with no connection to other schizophrenia genetic markers such as white matter volume and cortical thickness, noted Mr. Bohlken of the department of psychiatry at University Medical Center Utrecht (the Netherlands).
“White matter integrity should be considered a primary phenotype for linking genes to biological pathways that contribute to the development of schizophrenia,” the investigators concluded.
In a related editorial, Tyrone D. Cannon, Ph.D, of the departments of psychiatry and psychology at Yale University, New Haven, Conn., said that although reduced FA and cortical thickness are related to each other in schizophrenia, “this is not because of shared genetic causes. Thus, their phenotypic correlation in schizophrenia may reflect an additional degree of effect over and above that associated with their respective inherited substrates, as in a secondary effect.”
Find the full study (doi: 10.1001/jamapsychiatry.2015.1925) and editorial (doi: 10.1001/jamapsychiatry.2015.2111) in JAMA Psychiatry.