Daily Low Dose Aspirin May Increase Risk of Brain Bleeding. What to Know

An older man takes a pill.
New research has found daily aspirin may not be worth the risk for many older adults. Riska/Getty Images
  • A new study finds low dose aspirin use may increase the risk of brain bleeding in older adults, resulting in a hemorrhagic stroke.
  • Daily low dose aspirin is a common recommendation for preventing a heart attack or stroke in people with a previous cardiac event.
  • About 29 million people in the U.S. take daily aspirin even though they don’t have heart disease.

New research shows that daily low dose aspirin may increase the risk of brain bleeding in older adults, which could lead to hemorrhagic stroke. The findings also indicate that low dose aspirin did not significantly lower the risk of ischemic stroke.

The study, published July 26 in JAMA Network Open, adds to growing evidence that routine aspirin use for older adults with no previous stroke carries more risk than benefit.

Daily low dose aspirin is a common and effective strategy for preventing a heart attack or stroke in people with a previous heart attack, stroke, or other cardiovascular disease event.

But some people without cardiovascular disease take a daily aspirin, thinking it will prevent a first heart attack or stroke — in 2017, approximately 29 million Americans fell into this category. Nearly 7 million did so without their doctor’s recommendation.

The new study suggests that “we’re not really getting the benefit of reducing potential stroke and cardiovascular disease with low dose aspirin,” said Dr. Ched Nwagwu, neurosurgeon and medical director of MemorialCare Saddleback Medical Center’s Stroke Program in Laguna Hills, CA, who not involved with the new research.

“And, certainly, in older patients, there’s emerging data that [people taking daily low dose aspirin] are more prone to bleeding,” he told Healthline.

However, Nwagwu cautioned that more studies are needed to confirm these results.

“We can’t base our entire [clinical] practice just on this one trial,” he said.

Risks and benefits of low dose aspirin for stroke prevention

Ischemic strokes are the most common type of stroke and happen when blood flow to the brain is blocked, such as by a blood clot.

Aspirin thins the blood and helps prevent blood clots in the arteries that can cause a heart attack or stroke.

But the blood-thinning quality of aspirin can also cause bleeding in the gastrointestinal tract or a stomach ulcer.

Earlier clinical trials have found that while routine use of low dose aspirin reduced the risk of heart attack and stroke, it also increased the risk of bleeding in the stomach and intestines and inside the skull.

Older adults, in particular, are at higher risk of brain bleeding due to a ruptured blood vessel. They are also at high risk of falls, leading to head trauma and bleeding in the skull. 

Because of this, the authors of the new study wanted to investigate the risks and benefits of low dose aspirin use in older adults without a history of heart attack, stroke or other cardiovascular disease event.

Low dose aspirin increases brain bleeding risk

For the study, they analyzed data collected during the ASPREE (ASPirin in Reducing Events in the Elderly) clinical trial.

The trial included more than 19,000 people in Australia and the United States aged 70 years or older; or 65 years or older for U.S. participants who reported their race or ethnicity as Black or Hispanic.

Participants were randomly assigned to receive either 100 milligrams of (low dose) aspirin daily for more than four years, on average, or an inactive placebo.

The researchers found that 312 participants had a first ischemic stroke during the study. Of these, 24 people died due to the stroke.

This type of stroke is caused by an interruption in the blood supply to part of the brain. In contrast, a hemorrhagic stroke is caused by bleeding into the brain due to a ruptured blood vessel.

“Overall, aspirin did not result in a statistically significant reduction in the risk of ischemic stroke,” the authors wrote.

In addition, 187 people had bleeding inside the skull, including those with a hemorrhagic stroke. People taking a daily low dose aspirin had a 38% higher risk of this type of bleeding, compared to those in the placebo group, researchers found.

“The lack of benefit and potential risks from aspirin in primary stroke prevention provide further evidence in support of the recently published draft recommendation of the USPSTF [U.S. Preventive Services Task Force] against the routine prescribing of low dose aspirin as a primary prevention measure, especially in older persons,” the authors wrote.

Low dose aspirin not recommended for people with prior heart issues

Primary stroke prevention refers to the treatment of people with no history of stroke, as opposed to secondary stroke prevention, which is the treatment of people with a history of stroke.

In April 2022, the USPSTF revised its recommendations for who should take daily low dose aspirin to prevent cardiovascular disease problems such as heart attack and stroke.

The updated guidelines recommend that people 60 years or older do not start taking low dose aspirin for primary prevention of cardiovascular disease. 

For people ages 40 to 59 years with a 10% or greater risk of having a stroke or heart attack in the next 10 years, the decision “should be an individual one,” the guidelines say.

Another recent paper from the ASPREE trial, published this month in Annals of Internal Medicine, found that daily low dose aspirin also increases the risk of anemia in older adults.

The USPSTF guidelines and the new study don’t apply to people who are taking aspirin for pain relief, or people whose physician has advised them to take a daily low dose aspirin.

Daily aspirin is also still recommended in some cases as a treatment in people who have already had a stroke.

”If somebody had an intervention for cerebrovascular disease, such as a carotid stent or an intracranial stent, we know that long-term aspirin seems to prevent future events,” said Nwagwu. “So that’s going to prevent a secondary stroke.”

However, Nwagwu said the best treatment depends on the type of stroke a person had — a stroke due to atrial fibrillation (AFib) or irregular heart rhythm differs from a stroke due to a ruptured blood vessel. 

Those concerned about the risks of daily aspirin use should talk to their healthcare provider.

“People should have a conversation with their primary care physician, cardiologist or neurosurgeon,” said Nwagwu.

He thinks doctors should be asking questions like: “If a person is on low dose aspirin, do they really need it? What are our goals for treatment?”

In addition, they should be looking at the age of the patient, he said, “because the treatment goals may not be the same — and the risks certainly aren’t the same — for different age groups.”

Takeaway

A new study finds that older adults taking low dose daily aspirin are at higher risk for bleeding in the skull.

Additionally, taking aspirin did not decrease the risk of ischemic stroke.

The study adds to growing evidence that people should not take low dose aspirin on a daily basis to prevent heart disease.

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