A single dose of antidepressant medication is enough to produce dramatic changes in the brain within three hours, a study has found.
Volunteers had their brains scanned after taking the widely-prescribed drug escitalopram, marketed in the UK as Cipralex and Lexapro in the U.S.
The drug is a serotonin re-uptake inhibitor (SSRI) and aims to boost the level of this feel-good chemical in the brain.
SSRIs are believed to change brain connectivity in important ways, but the effects had generally been thought to take place over a period of weeks, not hours.
Study leader Dr Julia Sacher, from the Max Planck Institute for Human Cognitive and Brain Sciences in Germany said: ‘We were not expecting the SSRI to have such a prominent effect on such a short time scale or for the resulting signal to encompass the entire brain.’
The scans, which measured blood flow, showed that the drug reduced connectivity in most parts of the brain.
But there was an increase in connectivity within two specific brain regions, the cerebellum and thalamus.
Although SSRIs are among the most widely studied and prescribed antidepressants, it is still not entirely clear how they work.
Serotonin is a neurotransmitter – a messenger chemical that carries signals between nerve cells in the brain). It is thought to have a good influence on mood, emotion and sleep.
After carrying a message, serotonin is usually reabsorbed by the nerve cells (known as ‘reuptake’).
SSRIs work by blocking (‘inhibiting’) reuptake, meaning more serotonin is available to pass further messages between nearby nerve cells.
Dr Sacher said: ‘What we are seeing in medication-free individuals who had never taken antidepressants before may be an early marker of brain reorganisation.’
She added the new findings represent an essential first step toward clinical studies in patients suffering from depression.
The next step is to compare the brains of those in recovery and those of patients who fail to respond after weeks of SSRI treatment.
Dr Sacher said: ‘Understanding the differences between the brains of individuals who respond to SSRIs and those who don’t could help to better predict who will benefit from this kind of antidepressant versus some other form of therapy.
‘We hope our work will help to guide better treatment decisions and tailor individualised therapy for patients suffering from depression.’
The research is published in the journal Current Biology.
WIDELY-USED ANTIDEPRESANT COULD WARD OFF ALZHIEMER’S
A widely-used antidepressant could help slow the onset of Alzheimers disease.
Scientists say citalopram can significantly reduce the formation of plaques in the brain, which could go some way to warding off the disease.
The U.S. academics admit it is too early to recommend the drug to Alzheimers patients, but dementia charities last night welcomed the promising findings as providing vital new clues about the disease.
Plaque deposits are closely associated with declining memory and other symptoms of Alzheimers, so anything that can stop their build-up in the brain is likely to help ward off the condition.
The research, published in the journal Science Translational Medicine, found that a single dose of the antidepressant citalopram lowered production of the plaque protein amyloid beta by 37 per cent.
The experiment was conducted in healthy adults aged 18 to 50, but the scientists, from the universities of Washington and Pennsylvania, hope the findings can be replicated in elderly patients.
The drug, marketed in the UK as Cipramil, also had a dramatic effect on elderly mice, halting the growth of existing plaques and reducing the formation of new deposits by 78 per cent.
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