Olanzapine-induced weight gain plays a key role in the potential cardiovascular risk: evidence from heart rate variability analysis

Abstract

Patients with schizophrenia have a higher risk for cardiovascular disease (CVD) than the general population. Research has suggested that autonomic imbalance is a common pathway to increased morbidity and mortality for CVD. Heart rate variability (HRV) analysis is a non-invasive method that assesses autonomic imbalance, and low HRV is correlated with high cardiovascular risk. Olanzapine, a widely used antipsychotic drug, is considered to have good cardiac safety because of not causing significant corrected QT-interval (QTc) prolongation; however, it is still unclear whether olanzapine affects HRV. We recruited 83 patients with schizophrenia who were medication-free for at least 1 month and tested their HRV at the baseline and 4 weeks after treatment with olanzapine. We found that patients who had substantial weight gain (EWG) manifested significantly lower HRV than those who had non-substantial weight gain (NWG) and that HRV decrease was positively correlated to an increase in body mass index (BMI) and weight gain. Our results indicate that olanzapine-induced weight gain may play an important role in its potential cardiovascular risk. Since olanzapine has a very high potential for weight gain compared with other antipsychotics, further research is needed to explore its cardiovascular safety profile, specifically long-term cardiac safety.

Figure 1. Correlations among changes in body mass index and HRV measurements for the SCZ, EWG and NWG groups.

The change in body mass index (ΔBMI) is positively correlated with the change in the normalized low frequency power LFn (ΔLFn) and the LF/HF ratio (ΔLF/HF) and negatively correlated with the change in the standard deviation for the NN interval (ΔSDNN) and normalized high frequency power (ΔHFn) in both the SCZ and EWG groups (All P < 0.05). There is only a marginal negative correlation between ΔBMI and ΔHFn (P = 0.05) for the NWG group.