A drug used to treat constipation could boost a person's memory after just six days, a study by the University of Oxford suggests.
The pill Prucalopride, also known as Resolor, is already used to treat digestive problems but new research has shown it could also be used to tackle cognition impairments caused by psychiatric disorders like major depression, schizophrenia and bipolar disorder.
Researchers said the findings, presented at the European College of Neuropsychopharmacology Conference, provide "exciting early evidence" of the drug's benefits.
Forty-four healthy volunteers, aged 18 to 36, were split into two groups with half given prucalopride and the other half were given a placebo.
'Study provides exciting early evidence'
After six days of taking the pill, they attended the study where they were shown a series of images of animals and landscapes.
They viewed the images again, plus similar ones, during an MRI scan after which they performed a memory test.
Volunteers were asked to sort the images by those they had seen before and during the scan from a set of new pictures.
The people who took the constipation pill identified 81 per cent of the previously viewed images versus 76 per cent in the placebo group; their brain scans also showed enhanced activity in areas related to cognition.
The increased activity was shown in areas like the hippocampus and the right angular gyrus, both associated with memory, the researchers said.
'New approach to treat residual cognitive symptoms'
Dr Susannah Murphy, at the University of Oxford, said: "Even when the low mood associated with depression is well treated with conventional antidepressants, many patients continue to experience problems with their memory.
"Our study provides exciting early evidence in humans of a new approach that might be a helpful way to treat these residual cognitive symptoms".
Dr Angharad de Cates, also of the University of Oxford, said: "Statistical tests indicate that this was a fairly large effect - such an obvious cognitive improvement with the drug was a surprise to us."
The findings provide a "proof of concept" but warrant further study to see if the drugs could have clinical importance, the researchers said.