Steroids can alter the structure of the brain, according to a new study of commonly prescribed drugs.
Brain scans of nearly 25,000 people revealed that patients taking glucocorticoids had less white matter – the tissue that connects areas of the brain.
Dutch academics have said their “remarkable” findings could explain the drugs’ links to neurological problems.
Patients with asthma, arthritis, and eczema are all commonly prescribed steroids. But well-known side effects include anxiety, mood swings, and depression.
Dutch researchers, who studied the brains of nearly 25,000 people, found that those who took glucocorticoids had differences in the white and gray matter of their brains. Those who took the drugs – as tablets, injections or inhalations – experienced changes in parts of the brain involved in cognition and emotional processing
WHAT ARE GLUCOCORTICOIDS?
Glucocorticoids are a class of steroids taken by one percent of people in the UK and US.
Common types of medications include beclomethasone, an asthma medication, betamethasone, an arthritis medication, and eczema treatments, betamethasone and cortisone.
Medications are classified as inhaled or systemic, the latter including those taken as tablets or injected.
They are effective in reducing inflammation and suppressing the immune system.
But dozens of studies have linked glucocorticoids to serious side effects, such as high blood pressure, diabetes, and weakened bones.
Previous research has also suggested that the drugs trigger structural changes and shrink certain areas of the brain. But these concerned only a small number of people.
Although it has never been proven, steroids themselves are widely believed to be the cause of disabling symptoms.
The new study, published in the BMJ Open, does not definitively prove that drugs are to blame.
However, evidence from experts at Leiden University provides a potential mechanism that could explain the side effects.
Professor Onno Meijer and colleagues said it was “likely” that glucocorticoids caused changes in the brain.
Further research is needed to confirm the findings, as the exact consequences of the changes remain a mystery.
But they argued that the findings could, in part, “underlie the neuropsychiatric side effects seen in patients using glucocorticoids.”
One in 200 people in rich countries take glucocorticoids, compared to one in 100 in the UK and US.
Common types include beclomethasone (asthma) and betamethasone (arthritis).
Medications are classified as inhaled or systemic, the latter including tablets or injections.
They work by suppressing the immune system, which becomes overactive and causes conditions such as arthritis, asthma and eczema.
The researchers looked at data from 24,885 people included in the UK biobank.
The database contains health data from half a million Britons, who have undergone dozens of tests and been asked about their lifestyle.
Some 222 volunteers used systemic steroids, 557 took inhaled steroids and 24,106 took no steroids.
None had been diagnosed with neurological disorders or were taking psychotropic medications, such as antidepressants.
Professor Meijer and his team compared participants’ MRI brain scans and mood questionnaires.
Steroid users had “less intact” white matter compared to participants not taking the medication.
Taking glucocorticoids long-term and having the drugs in pill or injection form, rather than inhaled versions, was linked to the largest drop in white matter.
Systemic users had a larger caudate than those not using the drug.
Meanwhile, those taking inhaled steroids had smaller tonsils.
The caudate and amygdala are involved in cognitive and emotional processing.
Those who used systemic steroids also performed worse on a test measuring their processing speed than nonusers.
And they had higher rates of depression, agitation, and fatigue than nonusers.
Inhaled steroid users reported only more fatigue than nonusers.
The team noted that the participants were only asked a few questions about their mood and that the lower happiness levels may have been due to their condition, rather than the medications prescribed to treat it.
Steroids can alter the shape of your BRAIN, study finds