Genetic factors are unlikely to directly drive the increased rate of cardiovascular disease (CVD) in schizophrenia patients but may influence lifestyle, according to a paper in the American Journal of Psychiatry.
Schizophrenia is associated with a two- to threefold greater risk of CVD. Identifying the cause of the association could improve health outcomes in people with the mental disorder, who have a 10- to 20-year shorter life expectancy than the general population. Earlier work suggested that there may be a genetic component to the increase in cardiovascular risk.
To explore that suggestion, a team in Norway analyzed the results of multiple genome-wide association studies. The approach enabled the researchers to identify areas of overlap between the genetics of schizophrenia and cardiovascular risk factors.
The work revealed limited overlap in genetic variants between schizophrenia and blood pressure, a key driver of CVD. While the analysis suggested a genetic predisposition to high blood pressure is unlikely to explain the link between schizophrenia and CVD, it fond evidence that DNA may drive lifestyle habits associated with heart health risks. The finding that lifestyle, rather than genetics, drives cardiovascular risk could inform prevention strategies.
Notably, the researchers uncovered a potential genetic propensity to smoking, a habit that is prevalent in people with schizophrenia and a major risk factor for CVD. The genetic findings are in line with nicotine withdrawal studies and may explain why people with schizophrenia find it particularly hard to stop smoking tobacco.
“The addictive properties of nicotine may have a larger influence in people with schizophrenia, in line with evidence of greater nicotine dependence among individuals with schizophrenia than in the general population. In particular, patients with schizophrenia experience greater reinforcing effects of nicotine and more severe withdrawal symptoms during abstinence,” the researchers wrote.
Obesity rates are higher in people with schizophrenia as well, but the study suggests that this is unlikely to be a direct result of genetics. Instead, the lack of a genetic link suggests that a mix of antipsychotic medications, stress, and lifestyle factors are likely to explain the higher rate of obesity in people with schizophrenia.
