Roundup: One-Third of Adults Without Heart Disease have High ‘Bad Cholesterol’ Levels; and More News

Millions of Americans Have LDL Cholesterol Above New Recommended Targets, Study Finds

Nearly one in three U.S. adults without heart disease has LDL (the “bad”) cholesterol levels above the targets recommended in the new 2026 American College of Cardiology (ACC) and American Heart Association (AHA) cholesterol guidelines, according to a new study published in JAMA (Journal of the American Medical Association).

The findings also show that many people who could benefit from cholesterol-lowering treatment are not receiving it.

Researchers from Mass General Brigham analyzed health data from approximately 2,300 adults between the ages of 30 and 79 who participated in the National Health and Nutrition Examination Survey (NHANES) from 2021 to 2023. The survey represents an estimated 178 million U.S. adults.

“The gap between where the country’s cholesterol levels actually are and where the new guidelines say they should be is much wider than most people realize,” said lead author Shady Abohashem, M.D., M.P.H., of the Mass General Brigham Heart and Vascular Institute, in a news release.

What Changed in the New Cholesterol Guidelines?

The updated 2026 ACC/AHA guidelines include a new tool for estimating a person's risk of developing cardiovascular disease, which includes conditions affecting the heart and blood vessels, such as heart attack and stroke.

The guidelines also recommend lower LDL cholesterol goals for people at higher risk. LDL cholesterol can build up inside arteries, increasing the risk of blocked blood vessels that can lead to heart attacks or strokes.

For example, adults at low risk may consider treatment when LDL reaches 160 milligrams per deciliter (mg/dL) or higher. However, for people who already have heart disease and face a very high risk of future cardiovascular events, the recommended LDL target is below 55 mg/dL.

Many Americans are Not Meeting Cholesterol Goals

The study found that about one-third of adults without a history of heart attack, stroke, or other cardiovascular disease had LDL cholesterol levels above the new recommended targets. Among those individuals, approximately 76 percent were not taking any cholesterol-lowering medication.

The situation was even more concerning for people with established heart disease. Nearly four out of five had LDL cholesterol levels above the updated goal. Most were already taking cholesterol-lowering medication but had not lowered their LDL enough to meet the new recommendations. About 38 percent were not receiving any treatment.

Researchers say these findings point to two different challenges. People without heart disease who have elevated LDL often need to begin treatment, while those with existing heart disease may need more intensive therapy, such as a higher-dose statin, an additional non-statin medication, or newer cholesterol-lowering therapies.

Know Your LDL number

Heart disease remains the leading cause of death in the United States, but many heart attacks and strokes can be prevented by controlling cholesterol levels through healthy lifestyle habits and, when appropriate, medication.

The researchers note that the study reflects cholesterol levels before the new 2026 guidelines were introduced, providing a starting point for measuring future progress.

“The new guidelines give us a clearer goal than we’ve ever had,” Dr. Abohashem said. “For the public, the message is simpler: know your LDL number, know your personal target, and if you don’t know either, ask your doctor.”

Brain’s Immune System May Change Dramatically in Midlife, NIH Study Finds

A new National Institutes of Health (NIH)-funded study suggests that the brain’s immune system may undergo major changes beginning in midlife, a discovery that could help explain why aging is the greatest risk factor for dementia and other neurodegenerative diseases.

The research, published in Science, found that important immune cells in the hippocampus—a brain region essential for learning and memory—begin to change significantly between about ages 50 and 75. Scientists say the findings offer new clues about how aging may contribute to chronic brain inflammation, a process linked to Alzheimer’s disease and other forms of dementia.

While the study does not prove these changes cause dementia, it identifies a biological process that researchers believe deserves further investigation.

What are microglia?

The brain contains specialized immune cells called microglia, which act as its first line of defense. These cells remove damaged tissue, fight infection and help maintain healthy brain function.

For many years, scientists believed microglia formed before birth and continually renewed themselves throughout life. However, the new study suggests that many of these original cells gradually decline during later adulthood.

As they decrease, they appear to be replaced by immune cells that show stronger signs of inflammation and resemble immune cells normally found in the bloodstream.

Researchers believe this shift could make the aging brain more vulnerable to inflammation and disease.

Looking deeper into the aging brain

To better understand these changes, scientists analyzed hippocampal tissue donated after death by 40 adults between the ages of 20 and 95 who had no known neurological disease.

Using advanced single-cell analysis, researchers examined individual brain cells rather than studying tissue as a whole. They also analyzed the epigenome—chemical changes that influence how genes function without altering the DNA itself—and the three-dimensional organization of the genome.

Together, these techniques allowed researchers to identify changes that conventional genetic studies might have missed.

Other age-related changes were found

The study also found that cells responsible for maintaining the blood-brain barrier deteriorated with age. The blood-brain barrier is a protective network of cells that prevents harmful substances in the bloodstream from entering the brain.

Researchers also observed widespread changes in the organization of DNA inside brain cells. These structural changes were associated with altered gene activity and shifts in cell identity, suggesting they may be a fundamental feature of normal brain aging.

What the findings could mean

The researchers caution that these findings do not immediately lead to new treatments. Instead, they provide a better understanding of how the brain changes with age.

Future studies will explore why resident microglia disappear and whether the newly identified immune-cell transition directly contributes to Alzheimer’s disease and other neurological disorders.

If confirmed, the discovery could eventually help scientists develop therapies aimed at preserving healthy brain function, reducing harmful inflammation and lowering the risk of age-related cognitive decline.

How Much Coffee Is Safe? New Review Offers Reassurance for Most Adults

For millions of people, coffee is part of the daily routine. Now, a new scientific statement from the American Heart Association (AHA) suggests that, for most healthy adults, moderate amounts of caffeinated coffee are not only safe but may also be linked to better heart health.

The review, published in the journal Circulation, analyzed the latest research on caffeine and cardiovascular disease. While the relationship between coffee and heart health is complex, experts concluded that consuming up to 400 milligrams (mg) of caffeine per day—roughly the amount found in three to five 8-ounce cups of regular brewed coffee—is generally safe for most adults.

Moderate Coffee Intake May Benefit the Heart

Researchers found that drinking black, caffeinated coffee in moderation was associated with a lower risk of several cardiovascular conditions, including heart disease, heart failure and stroke. Some studies also linked moderate coffee consumption to a lower risk of developing Type 2 diabetes.

However, the authors emphasize that these findings show an association, not proof that coffee directly prevents disease. Most of the available research is observational, meaning it identifies patterns but cannot establish cause and effect.

Scientists also note that coffee contains hundreds of naturally occurring compounds besides caffeine. Some of these substances have antioxidant and anti-inflammatory properties that may contribute to potential health benefits.

Energy Drinks Are a Different Story

The report draws a clear distinction between coffee and highly caffeinated energy drinks.

While moderate coffee consumption appears safe for most people, large doses of caffeine—particularly from energy drinks and energy shots—may increase the risk of high blood pressure and abnormal heart rhythms, also called arrhythmias. An arrhythmia is a problem with the heart's normal electrical rhythm that can cause the heart to beat too fast, too slow or irregularly.

Energy shots often contain three to four times more caffeine per ounce than regular brewed coffee, making it much easier to consume excessive amounts.

Coffee Additives Matter

The potential benefits seen in research were linked primarily to plain black coffee.

Adding sugar, flavored syrups, whipped cream or other high-calorie ingredients may reduce coffee's health benefits by increasing calorie and sugar intake. Researchers say more studies are needed to understand exactly how these additions affect cardiovascular health.

The way coffee is brewed may also matter. Unfiltered coffee, such as French press, Turkish coffee or espresso, contains higher amounts of cafestol, a natural compound that can raise levels of low-density lipoprotein (LDL), often called "bad" cholesterol. Paper-filtered coffee removes much of this compound.

Caffeine Affects Everyone Differently

People process caffeine at different rates depending on factors such as genetics, age, metabolism and regular caffeine use.

Short-term effects may include temporary increases in blood pressure, heart rate, blood sugar and alertness. Some individuals may also experience heart palpitations or difficulty sleeping, even after relatively small amounts of caffeine.

Research found that drinking one to three cups of coffee daily was not associated with a higher risk of atrial fibrillation, a common type of irregular heartbeat. However, some studies found a greater number of premature ventricular contractions (PVCs), which are extra heartbeats that begin in the heart's lower chambers. While PVCs are often harmless, people with heart symptoms should discuss them with their healthcare provider.

The AHA concludes that, for most adults, moderate coffee consumption can be part of a heart-healthy lifestyle. Up to 400 mg of caffeine per day—about three to five cups of regular brewed coffee—appears safe and may even be associated with lower risks of several cardiovascular diseases.