Steroids Used For Asthma, Allergy Treatment Linked To Brain Decline

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 white matter of the brain, a new study found, Sandee La Motte reported for CNN.

Photo Insert: Doctors have long known that, if you give patients steroids, "the brain does shrink, but when you take them off the steroids, it comes back."

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

White matter is the tissue that forms connections between brain cells and the rest of the nervous system. Having less white matter can slow the brain's ability to process information, pay attention and remember. Lower levels of white matter have also been connected to psychiatric issues such as depression, anxiety, and irritability.

"This new study is particularly interesting in showing the extent to which white matter, which is required for neurons to connect with each other, is affected by medication use," said Thomas Ritz, a professor of psychology at Southern Methodist University who has researched the impact of steroids on people with asthma. He was not involved in the study.

However, "there's no reason for alarm," said neuroimmunologist Dr. Avindra Nath, the 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 you give patients steroids, "the brain does shrink, but when you take them off the steroids, it comes back," Nath said.

Due to brain plasticity -- the ability of the brain to reorganize its structure, functions, or connections -- "these could be temporary effects," he said. "They don't necessarily have to be permanent. White matter can repair itself."

The new study used data from the UK BioBank, a large biomedical research center that followed 500,000 residents of the United Kingdom from 2006 to 2010.

From that database, the researchers were able to find 222 oral glucocorticoid users and 557 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 testing and received a diffusion MRI of the brain. Researchers pulled that data and compared those MRI and cognitive findings to over 24,000 people in the database who did not use steroids.

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