Too low LDL cholesterol may boost risk for hemorrhagic stroke

Dr Xiang Gao at Pennsylvania State University in University Park, and coauthors conducted a study to examine the association between low-density lipoprotein (LDL) cholesterol (LDL-C) concentrations and intracerebral hemorrhage (ICH) risk and found that People with low density lipoprotein cholesterol (LDL cholesterol) concentrations under 70 mg/dL had a significantly higher risk of developing hemorrhagic stroke than people with low density lipoprotein (LDL) levels from 70 through 99 mg/dL.

The results of the study have appeared in the journal Neurology.

Current guidelines recommend lowering cholesterol for heart disease risk reduction. New findings indicate that if cholesterol dips too low, it may boost the risk of hemorrhagic stroke, according to researchers.

As is true with many things in nutrition, moderation and balance is key when deciding the optimal target level of LDL cholesterol," Gao said. "You can't go to either extreme — too high or too low. And if you're at a high risk for hemorrhagic stroke due to family history or risk factors like high blood pressure and heavy alcohol drinking, you may want to be extra careful about LDL cholesterol levels."

According to the researchers, low LDL cholesterol is recommended as a way to reduce the risk of a heart attack or ischemic stroke — the latter when a blood vessel in the brain becomes blocked by a clot. But previous research has suggested a link between very low LDL cholesterol levels and hemorrhagic stroke.

Chaoran Ma, a nutritional sciences graduate student at Penn State, said that while previous studies suggested this connection, there was a need for additional validation in a separate cohort.

"For our study, we wanted to expand the scope of knowledge in this area by investigating the issue prospectively in a large cohort with multiple LDL cholesterol measurements to capture variation over time," Ma said.

The study included 96,043 participants with no history of stroke, heart attack or cancer when the study began. LDL cholesterol levels were measured when the study began and yearly thereafter for nine years. Reported incidents of hemorrhagic stroke were confirmed by medical records.

The researchers found that participants who had LDL cholesterol levels between 70 and 99 mg/dL had a similar risk of hemorrhagic stroke. But, when LDL cholesterol levels dipped below 70 mg/dL, the risk of hemorrhagic stroke increased significantly. For example, the risk increased by 169 percent for participants with LDL levels less than 50mg/dL relative to those with LDL levels between 70 and 99 mg/dL. These findings were consistent after controlling for age, sex, blood pressure and medication.

The researchers concluded that they observed a significant association between lower LDL-C and higher risk of ICH when LDL-C was <70 mg/dL, and the association became nonsignificant when LDL-C ≥70 mg/dL. These data can help determination of the ideal LDL range in patients who are at increased risk of both atherosclerotic disease and hemorrhagic stroke and guide planning of future lipid-lowering studies.