London - Statins can make women more aggressive – but tend to reduce aggression in men, scientists claim.
Seven million Britons take the cholesterol-lowering drugs – a figure that is expected to rise.
Although previous research had showed a link between statins and aggression, the results were inconsistent. Now US scientists have conducted a more definitive study.
Professor of medicine Beatrice Golomb said: “There have been reports of some individuals developing irritability or aggression when placed on statins. We wanted to better understand how statins might affect aggression.”
So her team at San Diego School of Medicine in California put 692 men and 324 post-menopausal women on the statins simvastatin or pravastatin or a placebo. Neither researchers nor participants knew who was on the drug or a placebo for the six-month study.
The volunteers kept a diary of their social interactions, which were analysed and given scores for the number and severity of aggressive acts against others, themselves or objects.
Professor Golomb said all violent acts were rated, with the worst being hitting someone and causing serious injury. She added: “Punching a wall would get a certain number of points, punching a person would get more.”
The researchers also measured two key factors linked to aggression: The level of the hormone testosterone and whether any volunteers developed sleep problems – both of which are known to be affected by simvastatin. The study, which has been published in the journal PLOS ONE, found post-menopausal women became more aggressive, with the effect “stronger in women who began with lower aggression”.
One woman became so aggressive her husband asked for her to be taken off the trial. Her increasingly aggressive behaviour led to her being sacked from her job.It was later discovered she had been on one of the statins.
The effect on men was more complex – with three male participants showing “very large increases in aggression”. This was thought to be because statins disrupted sleep for two of them. But overall, there was a significant decline in aggressive behaviour for the men.
The reduction was also found to be stronger among younger men who tend to be more aggressive.
The researchers found that for volunteers on simvastatin, a drop in testosterone was linked to a greater drop in aggression.
The scientists are still unsure how to fully explain the findings, but Professor Golomb said: “Statins don’t affect all people equally – effects differ in men versus women and younger versus older.
“Either men or women can experience increased aggression on statins, but in men the typical effect is reduction.”
Statins did not increase testosterone levels in the women studied. Instead, Professor Golomb believes women became more aggressive because statins reduce their cell energy levels – a known cause of increased aggression. Other mechanisms may prevent this taking place in men.
She said the differences mirror other so-called traits of statins. For example they can increase blood sugar levels in some patients but cut them for others.
The UK government’s drugs advisory body, NICE, recommends them for all adults over 50 with a 10 percent risk of getting heart disease and the number is rising.
However, Sally Davies, the chief medical officer, has ordered a review into them over concerns about side-effects. The NHS says one in ten patients suffer side-effects, including nosebleeds, sore throats, headaches, nausea, stomach problems, muscle or joint pain and a higher risk of diabetes.
Daily Mail