Good' cholesterol may decrease your risk of Alzheimer's disease
- Good cholesterol or high-density lipoprotein (HDL) is essential to health. Still, the impact of HDL on the brain is not fully understood.
- Alzheimer’s disease is a disorder that impacts people’s ability to think and function in everyday life. Researchers are still working on developing treatments and understanding the condition.
- A recent study suggests that higher levels of small high-density lipoproteins might decrease the risk for Alzheimer’s disease.
Alzheimer’s disease is a debilitating condition that primarily affects older adults. People who have it can become forgetful and become unable to carry out tasks of daily living. Currently, the disorder has no cure. Researchers are still trying to understand how the disease develops, how to prevent it, and how to best treat it.
A recent study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association offers new insight. Researchers studied the connection between small HDLs or “good” cholesterol in the cerebrospinal fluid and the risk for Alzheimer’s disease. The results suggest that higher levels of small HDL were associated with a lower risk of developing Alzheimer’s disease.
Cholesterol is a substance that your body needs. For example, the body uses cholesterol to make certain hormones, properly digest food, and make new cells. The body makes cholesterol, but people can also get it from food sources.
As noted by the
The body’s HDL or “good” cholesterol helps to carry cholesterol back to the liver so that the liver can break it down. But HDLs can impact other areas of health in ways researchers do not fully understand. For example, researchers are still trying to understand how HDL levels affect the brain. The study authors note that the HDL in the brain is slightly different from the HDL in the rest of the body.
This damage causes people with Alzheimer’s disease to have memory, language, and decision-making problems. It can be debilitating, and those with Alzheimer’s disease often slowly lose their ability to function independently.
Research is ongoing about what causes Alzheimer’s disease and how we can best develop treatments.
The study in question included 180 participants aged 60 or older. Participants engaged in the study through the University of Southern California (USC) Alzheimer Disease Research Center (ADRC) and the Huntington Memorial Research Institute (HMRI) Aging Program.
Researchers looked at participants’ cognitive functions through a variety of cognitive tests. They took cerebrospinal fluid (CSF), the fluid surrounding the brain and the spinal cord, and plasma samples from participants and isolated the DNA. Researchers tested for the APOE ε4 gene from the DNA, a potential
Researchers then examined the levels of small HDL particles in the CSF. They found that higher levels of the small HDL particles were associated with better cognitive function among participants. They found this result to be the same even after accounting for the APOE ε4 gene, age, sex, and amount of education.
Results of the study may lead to the development of new treatments for Alzheimer’s disease. Study author Hussein Yassine noted the following to Medical News Today:
The discovery of lipid particles (LDL, HDL) in [the] blood led to several advances in drug discovery for cardiovascular disease treatment and prevention. Here for the first time, we measure HDL particles in cerebrospinal fluid as a surrogate of brain HDL and find that greater levels of small HDL correlate with better performance on cognitive measures.
Now that we have this biomarker, our next step is to figure out what promotes the formation of these small HDL particles in the brain. Such new discoveries could then lead to a new list of medications in our fight against Alzheimer’s.
The study authors noted that their study had several limitations. First, it is difficult to identify which of these particles has the protective properties because there are many subtypes of the small HDLs. They acknowledge that more research is needed to understand the interactions and differences between the HDLs in the brain and those in general circulation.
Researchers further acknowledge that the study’s findings cannot be generalized, and the study does not show cause. Further research can look at whether HDL levels can predict the development of cognitive problems and if increasing HDL levels could help prevent Alzheimer’s disease. Researchers note that future studies could include more participants and have more long-term follow-ups.
The Alzheimer’s Association was optimistic about the study’s results. Percy Griffin, Ph.D., the Director of Scientific Engagement for the Alzheimer’s Association, noted the following to MNT:
This work is interesting and adds to the growing body of research examining different species in the cerebrospinal fluid. These findings on small high-density lipoprotein particles are intriguing and may inform the development of biomarkers that can help predict how quickly people will progress through Alzheimer’s disease. However, the sample size is pretty small and more research is needed.
Sleep deprivation may lower 'good' cholesterol
Previous studies have suggested that lack of sleep may increase the risk for cardiovascular disease, and a new study may help explain why; researchers found that sleep deprivation may have a negative impact on cholesterol levels.
Published in the journal Scientific Reports, the study found that sleep loss leads to changes in genes that are responsible for regulating cholesterol levels.
What is more, two population cohorts reveal that people who experience sleep deprivation may have fewer high-density lipoproteins (HDL) – known as the “good” cholesterol – than those who have sufficient sleep.
HDL cholesterol is responsible for removing low-density lipoproteins (LDL) – the “bad” cholesterol – from the arteries.
LDL cholesterol contributes to atherosclerosis – a build-up of plaque in the arteries that can increase the risk for heart attack and stroke – so a robust HDL cholesterol level is important for protecting heart health.
The team reached its findings by conducting experimental and epidemiological analyses.
For the experimental analysis, the researchers enrolled 21 participants who were required to sleep in a laboratory-controlled condition for 5 nights
The sleep duration for 14 of these participants was restricted to just 4 hours a night, while the remaining seven participants enjoyed sufficient sleep each night.
Blood samples were taken from all subjects during the study period, which the team analyzed for gene expression and lipoprotein levels.
Compared with participants who had sufficient sleep, the researchers found that those who experienced sleep loss had reduced expression for genes that encode for lipoproteins – that is, there was reduced activity in genes that are responsible for regulating cholesterol levels.
For the epidemiological analysis, the researchers assessed the data of 2,739 participants from one of two Finnish population studies: Dietary, Lifestyle and Genetic determinants of Obesity and Metabolic syndrome (DILGOM) study, and the Cardiovascular Risk in Young Finns Study (YFS).
In the DILGOM study, participants completed questionnaires in which they were asked whether they got enough sleep each night. Subjects who answered “seldom” or “never” were deemed as having “subjective sleep insufficiency.”
In the YFS study, subjects were asked how many hours they slept each night and how many hours they need each night to fell well-rested. Their subjective sleep duration was then subtracted from their subjective sleep need in order to determine which participants could be deemed as having sleep deprivation.
On analyzing the blood samples of the participants, once again, the researchers found that subjects who were not getting sufficient sleep had reduced expression of lipoprotein-encoding genes, compared with those who were getting enough sleep.
Additionally, subjects who were experiencing lack of sleep had lower levels of circulating HDL.
The team says the findings from both analyses suggest that just a short period of sleep deprivation may have a big impact on health, and they may explain why people who fail to get enough sleep may be at greater risk for cardiovascular disease.
Study co-author Vilma Aho, from the University of Helsinki Sleep Team, says:
“The experimental study proved that just 1 week of insufficient sleep begins to change the body’s immune response and metabolism. Our next goal is to determine how minor the sleep deficiency can be while still causing such changes.”
Medical Myths: All about cholesterol
Cholesterol is an essential component of animal cell membranes; as such, it is synthesized by all animal cells. Regardless of its bad name, cholesterol is essential for life.
However, when present in high levels in the blood, it
Cholesterol, along with other substances, such as fat and calcium, builds up in plaques on the walls of arteries. Over time, this narrows the blood vessels and can lead to complications, including stroke and heart attack.
According to the Centers for Disease Control and Prevention (CDC), in 2015–2016,
The World Health Organization (WHO) estimates that raised cholesterol levels are responsible for
Given such prevalence, it is no surprise that misinformation about cholesterol is rife. So, to help us separate fact from fiction, Medical News Today enlisted the help of three experts:
- Dr. Edo Paz, a cardiologist and vice president of Medical at K Health
- Dr. Robert Greenfield, a board-certified cardiologist, lipidologist, and internist at MemorialCare Heart & Vascular Institute at Orange Coast Medical Center in Fountain Valley, CA
- Dr. Alexandra Lajoie, a noninvasive cardiologist at Providence Saint John’s Health Center in Santa Monica, CA
As mentioned in the introduction, cholesterol is a vital component of cell membranes. Aside from its structural role in membranes, it is also
So, although high levels are a risk factor for disease, without any cholesterol, we could not survive.
As Dr. Greenfield explained to MNT: “Cholesterol isn’t bad. It’s an innocent bystander that is being mishandled in our modern lifestyle today.”
“Our bodies weren’t designed to live in an environment where food was in excess, and so when cholesterol is in excess, it will be deposited in our body. And that deposit center can often be our blood vessels, and that’s when it’s bad for us.”
– Dr. Robert Greenfield
Beyond cholesterol’s functions in the body, the way in which it is transported also makes a difference to whether it is detrimental to health.
Cholesterol
Low-density lipoprotein (LDL) carries cholesterol from the liver to cells, where it is used in several processes. People sometimes term LDL “bad” cholesterol, because high levels of LDL cholesterol in the bloodstream increase the risk of cardiovascular disease.
High-density lipoprotein (HDL) is often referred to as “good” cholesterol, because it transports cholesterol back to the liver. Once there, cholesterol is removed from the body, thereby reducing cardiovascular risk.
“Oh, yes you can!” according to Dr. Greenfield. “Cholesterol balance is really a function of what we eat but also our genetics. For example, a person can be born with a genetic tendency to not process cholesterol efficiently.”
“Because it’s genetic,” he explained, “it has been called familial hypercholesterolemia, and it might be as common as
Dr. Paz concurred: “Even if you have a healthy weight, your cholesterol can be abnormal. Other factors that impact your cholesterol are the foods you eat, your exercise habits, whether you smoke, and how much alcohol you drink.”
Additionally, as Dr. Lajoie told us, people who have a healthy weight might have high cholesterol levels, while some people who have overweight may not have high cholesterol. “Cholesterol levels are affected by genetics, thyroid function, medications, exercise, sleep, and diet,” she explained.
“There are also factors that you cannot modify and which can contribute to high cholesterol, like your age and your genetics,” she continued.
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