How Toxic Proteins Reach Brain Tissue
As I've discussed before, amyloid protein is a sticky protein fragment that collects in brain tissue and often gets blamed for causing Alzheimer's disease. But as we’ve reported, science shows that there are plenty of people with brains full of amyloid whose memories work just fine. And many scientists loudly disagree about amyloid beta’s influence on our thinking processes. Researchers at Curtin University in Bentley, Australia have some important new information to add to the debate. The Australian researchers say that the amyloid beta protein made by brain cells seems to be relatively benign while the amyloid protein made by the liver and released into the blood stream harms brain function significantly. Up until now, say the Australians, it's been impossible for lab tests to distinguish between amyloid beta formed in the brain and amyloid made by the liver that travels into the brain through the blood-brain barrier. Their tests on rodents used animals genetically engineered to only produce amyloid in the liver, not the brain. Therefore, their study, they assert, displays the difference.1 These scientists also say that their analysis indicates that the amyloid circulating in the bloodstream affects the blood-brain barrier in a way that makes it leakier and allows the toxic amyloid to cross into brain tissue.Vascular Dementia May Start in the Liver
Meanwhile, researchers at the National Institute on Aging (NIA) in Baltimore have begun to investigte how cholesterol that originates in the liver may also be connected to memory issues and brain dysfunction – in this case leading to vascular dementia. Vascular dementia occurs when impaired blood flow to the brain causes memory problems and other cogntive difficulties. These scientists point out that studies have associated high cholesterol with an increased risk of both Alzheimer's disease and vascular dementia – even though the blood-brain barrier doesn't allow cholesterol to enter the brain. But the study at the NIA now shows that a malfunction of the body's processes for breaking down cholesterol into bile acids (a process called cholesterol catabolism) may be the missing link connecting cholesterol to brain problems. While the researchers don't understand all of the intricacies of these processes, their analysis of the brain health of more than 26,000 people shows that in men (but not women) having low levels of bile acids in the blood is linked to a bigger risk of vascular dementia. They also discovered that taking drugs called bile acid sequestrants that block bile acid absorption into the bloodstream can also increase the risk of dementia. (Bile acid sequestrants are frequently taken to lower LDL cholesterol. This is likely why side effects of some cholesterol-lowering medications include memory loss.)What Can You Do?
While the NIA scientists are still trying to understand precisely how the bile acids affect the brain, the message of their study – and the Australian research – is clear. They show, once again, that leading a healthy lifestyle is crucial for keeping your brain functioning properly. Your brain can't be healthy if the rest of your body and organs like your liver aren't functioning properly. So eating a diet filled with fruits and vegetables while also getting plenty of exercise is crucial for the health of your body and brain. Research shows, for example, that exercise may help keep your blood-brain barrier working more efficiently – allowing fewer toxins to enter brain tissue.2 Plus, the phytochemicals and other nutrients in vegetables may help brain function by keeping your liver function on track.3 This kind of diet and lifestyle will also help you keep your cholesterol levels in check, often times without the need of medication. And don't forget to keep your daily stress levels down! Studies indicate that being stressed out all the time may also be connected to leaks in the blood-brain barrier. So, go for more stress-relieving walks and try out some meditative stress relief techniques.4 Your brain—and your body— will thank you.