We all know by now that not all cholesterols are created equal. There’s LDL ("bad") cholesterol, which clogs the arteries and raises risk of heart disease and stroke. And then there’s HDL ("good") cholesterol, which has been show to protect the heart and possibly ward off some forms of cancer. Now, a new study finds that HDL cholesterol may actually protect the brain from Alzheimer’s disease, giving us even more reason to get those cholesterol levels where we want them.
People with higher HDL cholesterol levels were at the lowest risk for developing the disease. The results were true even after other factors like age, education level, gender, and genetic predisposition were taken out of the equation.
In the new study, the research team followed over 1,100 seniors who had no symptoms of Alzheimer’s (or any kind of dementia) at the beginning of the study. The participants were retested every 18 months for about 11 years. At the end of this time period, 101 people developed Alzheimer’s disease. The researchers analyzed the data to see if there was a connection between one’s blood fats and his or her risk of developing Alzheimer’s disease.
Indeed, the team found that there was an inverse relationship between HDL cholesterol and Alzheimer’s risk: in other words, people with higher HDL cholesterol levels were at the lowest risk for developing the disease. The results were true even after other factors like age, education level, gender, and genetic predisposition were taken out of the equation.
Why would cholesterol protect the brain in this way? According to the study, low HDL levels have been shown to be a marker for fatty build-up in the carotid artery (which supplies the head with oxygen-rich blood), which could trigger cognitive problems through a number of possible mechanisms. The good cholesterol may also help the brain rid itself of excess cholesterol, though more research will be needed to determine exactly what mechanisms are really at play here.
While researchers continue to tease apart these theories, it’s probably not a bad idea to get the bad cholesterol under control, while still eating moderate amounts of foods that are rich in healthy fats, like olive oil, nuts, and avocados.
The study was conducted by researchers at Columbia University's Taub Institute for Research on Alzheimer's Disease, and published in the December 2010 issue of Archives of Neurology.