Study links common asthma medications to brain changes

A new study published in The BMJ found a link between systemic and inhaled glucocorticoids — medications commonly used for asthma and chronic obstructive pulmonary disease (COPD) — and structural and volume changes in gray and white matter in the brain.

The results are based on a cross-sectional study of 779 subjects taking the drugs and 24,106 controls enrolled in the UK Biobank between 2006 and 2010.

Of the patients in the biobank, 222 used systemic glucocorticoids and 557 used inhaled corticosteroids. Systemic glucocorticoids are taken orally or by injection.

“Both systemic and inhaled glucocorticoid use are associated with reduced white matter integrity and limited changes in [gray matter volume]’ researchers wrote. White matter plays a role in neuronal connectivity and brain signaling, she added.

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“This association may contribute to the neuropsychiatric side effects of glucocorticoid medications, especially with chronic use.”

Those using systemic steroids performed worse on a processing speed test compared to controls, and reported more depressive symptoms, apathy, and restlessness than nonusers.

Long-term use of these drugs has previously been linked to anxiety, depression, mania, and delirium. The current study marks the largest of its kind, as the drugs under review are widely used to treat a variety of conditions, thanks to their immunosuppressive properties.

All study participants underwent diffusion tensor imaging (DTI) and magnetic resonance imaging (MRI), were mostly in their 60s and had no history of psychiatric disorders.

Associations between less intact white matter structure were greater in systemic users compared to inhaled corticosteroid users. Data also showed that effects may be greater in long-term users.

Systemic use was also associated with greater caudate compared to controls. However, inhaled users showed a smaller amygdala on average. The caudate and amygdala are gray matter structures involved in cognitive and emotional processing, researchers explained.

“While a causal relationship between glucocorticoid use and brain changes is likely based on current and previous studies, the cross-sectional nature of this study does not allow for formal conclusions about causality,” they cautioned.

Mood swings were also assessed only during a period of the past two weeks, while changes may have been related to the condition a patient was receiving the medication for, not the steroid itself.

“Since these drugs are widely used, awareness of these associations is necessary in all medical specialties and research into alternative treatment options is warranted,” the authors concluded.