New research links the use of glucocorticoids with changes in white matter microstructure – which may explain the development of anxiety, depression, and other neuropsychiatric side effects related to these drugs, investigators say.
Results from a cross-sectional study showed that use of both systemic and inhaled glucocorticoids was associated with widespread reductions in fractional anisotropy (FA) and increases in mean diffusivity.
Glucocorticoids have “a whole catalogue” of adverse events, and effects on brain structure “adds to the list,” co-investigator Onno C. Meijer, PhD, professor of molecular neuroendocrinology of corticosteroids, department of medicine, Leiden University Medical Center, the Netherlands, told this news organization.
The findings should encourage clinicians to consider whether doses they are prescribing are too high, said Dr. Meijer. He added that the negative effect of glucocorticoids on the brain was also found in those using inhalers, such as patients with asthma.
The findings were published online in the BMJ Open.
Serious side effects
Glucocorticoids, a class of synthetic steroids with immunosuppressive properties, are prescribed for a wide range of conditions, including rheumatoid arthritis and asthma.
However, they are also associated with potentially serious metabolic, cardiovascular, and musculoskeletal side effects as well as neuropsychiatric side effects such as depression, mania, and cognitive impairment.
About 1 in 3 patients exposed to “quite a lot of these drugs” will experience neuropsychiatric symptoms, Dr. Meijer said.
Most previous studies that investigated effects from high levels of glucocorticoids on brain structure have been small and involved selected populations, such as those with Cushing disease.
The new study included participants from the UK Biobank, a large population-based cohort. Participants had undergone imaging and did not have a history of psychiatric disease – although they could have conditions associated with glucocorticoid use, including anxiety, depression, mania, or delirium.
The analysis included 222 patients using oral or parenteral glucocorticoids at the time of imaging (systemic group), 557 using inhaled glucocorticoids, and 24,106 not using glucocorticoids (the control group).
Inhaled steroids target the lungs, whereas a steroid in pill form “travels in the blood and reaches each and every organ and cell in the body and typically requires higher doses,” Dr. Meijer noted.
The groups were similar with respect to sex, education, and smoking status. However, the systemic glucocorticoid group was slightly older (mean age, 66.1 years vs. 63.3 years for inhaled glucocorticoid users and 63.5 years for the control group).
In addition to age, researchers adjusted for sex, education level, head position in the scanner, head size, assessment center, and year of imaging.
Imaging analyses showed systemic glucocorticoid use was associated with reduced global FA (adjusted mean difference, -3.7e-3; 95% confidence interval, -6.4e-3 to 1.0e-3), and reductions in regional FA in the body and genu of the corpus callosum versus the control group.
Inhaled glucocorticoid use was associated with reduced global FA (AMD, -2.3e-3; 95% CI, -4.0e-3 to -5.7e-4), and lower FA in the splenium of the corpus callosum and the cingulum of the hippocampus.
Global mean diffusivity was higher in systemic glucocorticoid users (AMD, 7.2e-6; 95% CI, 3.2e-6 to 1.1e-5) and inhaled glucocorticoid users (AMD, 2.7e-6; 95% CI, 1.7e-7 to 5.2e-6), compared with the control group.
The effects of glucocorticoids on white matter were “pervasive,” and the “most important finding” of the study, Dr. Meijer said. “We were impressed by the fact white matter is so sensitive to these drugs.”
He noted that it is likely that functional connectivity between brain regions is affected by use of glucocorticoids. “You could say communication between brain regions is probably somewhat impaired or challenged,” he said.
Subgroup analyses among participants using glucocorticoids chronically, defined as reported at two consecutive visits, suggested a potential dose-dependent or duration-dependent effect of glucocorticoids on white matter microstructure.
Systemic glucocorticoid use was also associated with an increase in total and grey matter volume of the caudate nucleus.
In addition, there was a significant association between inhaled glucocorticoid use and decreased grey matter volume of the amygdala, which Dr. Meijer said was surprising because studies have shown that glucocorticoids “can drive amygdala big time.”