Commonly prescribed steroids, including inhalers for asthma, may be causing changes in the structure and volume of white and grey matter in the brain.
This is obviously serious news.
Glucocorticoids – used for treating allergies, rheumatoid arthritis, osteoarthritis, Crohn’s disease and other types of inflammatory bowel disease and other conditions – are the most commonly prescribed anti-inflammatory and immunosuppressant medications globally.
But the suggestion they might be damaging the brain isn’t that surprising or new.
Previously research found evidence that long-term medical steroid use is associated with structural abnormalities and shrinkage of certain areas of the brain.
Neuropsychiatric side effects are common.
According to a 2014 review in the American Journal of Psychiatry, long-term use of glucocorticoids is associated with sometimes severe psychological, cognitive, and behavioural disturbances – such as psychosis, mania, depression, panic disorder and delirium.
‘‘The majority of patients experience less severe but distressing and possibly persistent changes in mood, cognition, memory, or behaviour during glucocorticoid treatment or withdrawal,” write the authors of that review.
The researchers behind the new study – from the Division of Endocrinology, Leiden University Medical Centre, in the Netherlands – say the brain changes that they reported this week in the British Medical Journal, might help to explain the neuropsychiatric effects ‘‘frequently seen after long-term use, say the researchers’’.
Glucocorticoids have a history
Glucocorticoids are a powerful treatment for inflammation and for auto-immune systems that are causing more problems than doing good.
As an explainer from the BMJ: While very effective, both systemic and inhaled steroids are associated with many potentially serious metabolic, cardiovascular and musculoskeletal side effects, and those neuropsychiatric effects.
The previously published research that found links between long-term medical steroid use and brain abnormalities involved small numbers of people with specific conditions.
The Netherlands researchers wanted to know if these links ‘‘might also be observed in a broader sample of medical steroid users, including those using inhaled steroids for respiratory conditions, such as asthma’’.
What was the study?
Using data from the UK Biobank, compared the brain scans of people using steroids and people who didn’t use them.
The participants included 222 people using systemic steroids (treatments that affect the entire body), and 557 using inhaled steroids that are more localised. There were 24,106 non-users.
The authors say none of the study participants had previously been diagnosed with neurological, psychiatric or hormonal (endocrinological) disorders or was taking mood-altering drugs, such as antidepressants.
The participants were assessed in a questionnaire that revealed ‘‘certain aspects of mood over the previous fortnight’’.
What were the results?
Comparison of the MRI scan results showed that both systemic and inhaled steroid use was associated with less intact white matter structure than was seen on the scans of those not on these drugs.
White matter has a role in neuronal connectivity and signalling in the brain.
Systemic users were found to be more affected by white matter damage than users of inhaled steroids.
The authors further detailed analysis suggested that the effects ‘‘might be even larger among long-term users’’.
Grey matter was affected too
Systemic steroid use was associated with a larger caudate compared with no use of the drugs.
The caudate is a pair of C-shaped grey-matter structures deep in the brain.
They make up part of the basal ganglia. The caudate is involved with high-level functioning, including planning movement, memory, learning and emotion.
The researchers found that use of inhaled steroids was associated with a smaller amygdala, also a grey matter structure primarily involved in the processing of emotions and memories associated with fear.
Participants took some tests
Systemic steroid users also performed worse on a test designed to measure processing speed than non-users.
Also, in their questionnaires, they reported ‘‘significantly more depressive symptoms, apathy, restlessness and fatigue/lethargy than non-users’’.
Inhaled steroid users only reported more tiredness and lethargy, and to a lesser degree than systemic steroid users.
The authors conclude: ‘‘This study shows that both systemic and inhaled glucocorticoids are associated with an apparently widespread reduction in white matter integrity, which may in part underlie the neuropsychiatric side effects observed in patients using glucocorticoids.”
But they said the nature of their study meant they couldn’t claim to have proven a causal connection between steroid use and these associated problems.
