Almost 80% of Schizophrenia Risk is Down to Genetics
Genetics account for as much as four out of five cases of schizophrenia according to new research.
By applying a new statistical approach to data collected on more than 30,000 pairs of twins, researchers have produced the most accurate figures to date on risk factors for the condition, potentially helping us identify the genes responsible for its symptoms. The findings were published in the journal Biological Psychiatry.
These kinds of studies provide unique comparisons when it comes to genetics; identical twins have 100 percent of their genome in common, whereas non-identical twins share roughly 50 percent of their genes.
“This study is now the most comprehensive and thorough estimate of the heritability of schizophrenia and its diagnostic diversity. […] It indicates that the genetic risk for disease seems to be of almost equal importance across the spectrum of schizophrenia,” Dr. Rikke Hilker of the Center for Neuropsychiatric Schizophrenia Research at Copenhagen University Hospital, and first author of the study said.
“Hence,” she added, “genetic risk seems not restricted to a narrow illness definition, but instead includes a broader diagnostic profile.”
Their findings show that roughly 1 per cent of the twins had developed schizophrenia and 2.5 per cent had schizophrenia-like disorders.
If one of the identical twins was afflicted, there was a 33 percent chance the other would be too, whilst in non-identical twins, this plunged between seven and nine percent. Based on this – and without identifying the genes responsible – the team calculated that 73 percent of schizophrenia-like disorders, and 78 percent of schizophrenia cases, were down to genetics.
Ultimately, this research confirms ‘what was already known’: conditions that manifest mentally tend to have a genetic or neurological basis more than one may assume. However, a major problem with this study is that environmental factors are assumed to be significant, and do not impact on the genetic makeup of a person. This means that the role of genes is being overestimated, but it’s not clear by how much.