Common Steroids Used for Asthma, Allergies Linked to Brain Decline: Study

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(CNN) --

Taking oral or inhaled glucocorticoids, a type of steroid used to curb inflammation in asthma and other autoimmune disorders, may be linked to damaging changes in the brain's white matter, according to a new study.

"This study shows that both systemic and inhaled glucocorticoids are associated with an apparently generalized reduction in white matter integrity," wrote study author Merel van der Meulen, a postdoctoral student at Leiden University Medical Center. , Netherlands, in the study published Tuesday in the academic journal BMJ Open.

White matter is the tissue that forms the connections between brain cells and the rest of the nervous system.

Having less white matter can slow down your brain's ability to process information, pay attention, and remember.

Low levels of white matter have also been linked to psychiatric problems such as depression, anxiety, and irritability.

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"This new study is especially interesting because it shows the extent to which white matter, necessary for neurons to connect to each other, is affected by medication use," said Thomas Ritz, professor of psychology at Southern Methodist University, who has investigated the impact of steroids on people with asthma.

He did not participate in the study.

However, "there is no reason to be alarmed," said neuroimmunologist Dr. Avindra Nath, clinical director of the National Institute of Neurological Disorders and Stroke, who was also not involved in the study.

Doctors have long known that if patients are given steroids, "the brain shrinks, but when the steroids are taken off, it recovers," Nath said.

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Because of brain plasticity -- the brain's ability to reorganize its structure, functions or connections -- "these could be temporary effects," he said.

"They don't have to be permanent. White matter can repair itself."

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Widespread use

Glucocorticoids are some of the most widely prescribed anti-inflammatory drugs due to their widespread use in various conditions, according to experts.

In addition to asthma, oral and inhaled glucocorticoids can be used to treat allergies, chronic obstructive pulmonary disease (COPD), Crohn's disease and other types of inflammatory bowel disease, eczema and other skin conditions, lupus, tendinitis, multiple sclerosis, osteoarthritis and rheumatoid arthritis.

However, glucocorticoid inhalers should not be confused with quick-relief inhalers used to stop an asthma attack.

Quick-relief inhalers contain nonsteroidal medications that relax the muscles in your lungs, such as albuterol, levalbuterol, and pirbuterol, which can open your airways in minutes.

Inhaled corticosteroids do not work in an emergency: they are prescribed for long-term control of inflammatory conditions.

Previous research has linked long-term use of oral glucocorticoids to structural abnormalities of the brain and shrinkage of certain areas of the brain, as well as mental health problems such as anxiety, depression, confusion, and disorientation.

Studies have also shown that people who have lived with asthma have higher rates of cognitive and memory decline later in life than people without the disease.

However, experts note that much of the previous research has been on a small scale and, at times, inconclusive.

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The new study used data from the UK BioBank, a large biomedical research center that followed 500,000 UK residents between 2006 and 2010. From that database, the researchers were able to find 222 oral glucocorticoid users and 557 oral glucocorticoid users. of inhaled glucocorticoids who did not have a previous diagnosis of any neurological, hormonal, or mental health disorder.

Those people underwent cognitive and mental health tests and received a diffusion-weighted MRI of the brain.

The researchers mined that data and compared those cognitive and MRI findings with those of more than 24,000 people in the database who had not used steroids.

"To our knowledge, this is the largest study to date evaluating the association between glucocorticoid use and brain structure, and the first to investigate these associations in inhaled glucocorticoid users," the study authors wrote.

Inhalers had the least impact

The study found the greatest amount of white matter damage in people who take oral steroids regularly for long periods of time.

The mental processing speed of chronic oral steroid users was lower than that of non-users.

People taking oral steroids also reported more apathy, depression, fatigue, and restlessness than non-steroid users.

The study found that the least impact on white matter occurred in people using inhaled steroids.

This is consistent with what doctors see in clinical practice, said pulmonologist Dr. Raj Dasgupta, an assistant professor of clinical medicine at the University of Southern California Keck School of Medicine, who was not involved in the study.

"We don't see side effects as often with the inhaled form of glucocorticoids," he said.

"And of course the mainstay of therapy for allergies and asthma is always going to be avoiding triggers and making lifestyle modifications."

Pulmonologists and rheumatologists are cautious about prescribing the lowest dose of steroids needed to control symptoms, Dasgupta said, because of the large number of side effects of steroid use that can also affect health, including brain health.

"As a clinician, the moment you start putting a person on these drugs, you immediately think, 'How can I get them off medication safely and in a timely manner? Steroids cause weight gain, and weight gain weight is always going to be a risk for developing diabetes and high blood pressure," Dasgupta said.

"When steroids are given to people with diabetes, their blood sugar level may rise," he added.

"When you take steroids acutely, you can definitely have insomnia and trouble sleeping, and when you take steroids long term, you have a high risk of infections because they are an immunosuppressant."

more research needed

The new study had limitations.

For one thing, it couldn't determine steroid dosage or track adherence, Ritz said.

"We know that only about 50% of asthma patients take their medication as prescribed, and possible overreporting of intake is also a problem," Ritz said.

"Inhaled corticosteroids, which reduce inflammation locally, should be taken as regularly as possible, but at the lowest possible dose that will control asthma."

"This study gives us another reason to keep doses low," he added.

According to the study authors, another limitation was that they could not differentiate between people taking steroid tablets and those using infusions.

"The study mainly confirms what we've known for a long time in asthma management: take as few systemic (oral) corticosteroids as possible, as long as you're not dealing with severe asthma. Stick to inhaled steroids and discuss discuss plans with your treating physician to reduce medication regimens during good times," Ritz said.

"This is a very well done study," said Nath.

"But the findings call for another study to see how long these effects last and how they can be reversed."

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