September 01, 2022
People who take oral or inhaled glucocorticoids – steroids commonly used to curb inflammation in asthma and allergies – may experience changes in the white matter of the brain, leading to cognitive decline, a new study finds.
White matter is the tissue that connects brain cells to the rest of the nervous system. Previous studies have shown that a decrease in white matter is linked to cognitive problems, including difficulties processing information, attention span and memory. Research also has suggested that having less white matter is linked to certain mental health conditions, including depression and bipolar disorder.
The new study is the largest and most conclusive to find that steroid damages the white matter of the brain. Researchers found that people who use oral steroids over long periods of time experienced the most damage to their white matter, and that their mental processing speeds were lower. People on oral steroids also reported more apathy, depression, fatigue and restlessness than the people who didn't use steroids.
Among steroid users, those who used inhaled steroids saw the smallest loss of white matter.
"To the best of our knowledge, this is the largest study to date assessing the association between glucocorticoid use and brain structure, and the first to investigate these associations in inhaled glucocorticoid users," the researchers wrote.
However, neuroimmunologist Dr. Avindra Nath, of the National Institute of Neurological Disorders and Stroke, told CNN that there is "no reason for alarm," saying the decline in white matter most likely is temporary. The brain has the ability to reorganize its structure and connections, so the white matter most likely can repair itself, he added.
Nath, who was not involved in the research, added that another study is necessary to determine how long the effects last and whether they can be reversed.
In addition to treating asthma and allergies, oral and inhaled glucocorticoids are used to treat chronic obstructive pulmonary disease, Crohn's disease and other types of inflammatory bowel disease, eczema and other skin conditions, lupus, tendinitis, multiple sclerosis, osteoarthritis and rheumatoid arthritis.
The quick-relief inhalers used to stop an asthma attack do not contain steroids. The inhalers use albuterol, levalbuterol or pirbuterol to relax the muscles in the lungs and open the airways within minutes.
Inhaled corticosteroids are used for long-term control of inflammation, and are known to cause some serious adverse side effects – especially when taken for a long time – including an increase in blood sugar level, suppression of the immune system, and a delay in wound healing. Long-term use also can lead to the loss of muscle tissue, a fatty hump between the shoulders, pink stretch marks, weakened bones, diabetes, high blood pressure, an irregular menstrual cycle, decreased libido, fatigue and depression.
Because of the risk of serious adverse effects, doctors generally prescribe the smallest possible doses of steroids needed to control symptoms.
For the study, the researchers analyzed cognitive and mental health data on 222 oral glucocorticoid users and 557 inhaled glucocorticoid users who had not been diagnosed with neurological, hormonal or mental health disorders. Their testing results were compared to data from 24,000 people who did not use steroids.
The researchers acknowledged some limitations to their study. They weren't able to determine how well participants adhered to taking their medications. They also could not distinguish between people who took steroid tablets and infusions.