A common painkiller used by millions could boost memory and intelligence, a study has found.
Ibuprofen, an anti-inflammatory taken to relieve headaches, toothache, back pain and cold symptoms, may also speed up reaction times, researchers claim.
The health benefits are so significant, they suggest, that the pills are as good for the brain as lowering high blood pressure.
However, taking paracetamol, another common painkiller, was found to have the opposite effect and could actually worsen memory.
The University College London study looked into the cognitive effects of common medicines on about half a million people in the UK.
Researchers found that drugs used to treat pain, inflammation, osteoarthritis, heart disease, asthma, allergies and high blood pressure may have the greatest positive effects.
The over-the-counter painkiller paracetamol and the prescription antidepressant fluoxetine had the most adverse effects on memory and problem-solving.
Researchers point out that their results only suggest a link between the drugs and these effects, and are not proof that they cause them directly.
But they add that clinical trials of all new medications should look at the potential impact on the brain to allow doctors to make a choice about the best drugs for patients to take.
Neurologist Martin Rossor, the study’s senior author, said: “The cognitive side-effects of commonly used drugs may have significant impact. Medications are widely employed and many have adverse cognitive effects. Consideration should be given to a routine assessment of cognition in trials.”
There has been little research on the cognitive effects of common drugs.
One problem is that many are taken most frequently by older people and often in conjunction with other medications, which means it is hard to isolate what might be causing the effect.
Any ill-effects on cognition may also be wrongly attributed to advancing age.
The study, which was funded by charity The Health Foundation, used medical data from about 540,000 men and women, aged up to 73.
It included information on what medication they were taking and how they performed in tests which measured reaction times, memory, reasoning skills and problem-solving abilities.
The scores of those using the drugs were compared with those who did not use the medication.
The results, published in the journal Brain And Behaviour, revealed that people who were taking one of ten common drugs performed better in the tests than those who did not.
Other pain killers which had a positive effect included aspirin, codeine and diclofenac, also known as Voltaren.
Omega 3 triglycerides, used to treat heart disease, glucosamine for osteoarthritis, atorvastatin for lowering cholesterol, omeprazole for heartburn, indigestion drug lansoprazole and those taking a multivitamin also saw benefits.
The migraine treatment amitriptyline was also linked to the biggest negative effects.