Statins make women more aggressive but lower aggression in men, according to new research.
Hailed as wonder drugs, statins are widely used to manage blood cholesterol levels and reduce the risk of heart disease.
Some individuals develop irritability or aggressionProf Beatrice Golomb
Previous studies raised questions about adverse changes in behaviour while on statins, such as irritability or violence, but the findings were inconsistent.
Now, in the first randomised trial to look at statin effects on behaviour, researchers found aggressive behaviour typically declined among men placed on statins, but increased among women on the drugs.
Lead author Professor Beatrice Golomb, of the San Diego School of Medicine at the University of California, said: “Many studies have linked low cholesterol to increased risk of violent actions and death from violence – defined as death from suicide, accident and homicide.
“There have been reports of some individuals developing irritability or aggression when placed on statins. Yet in contrast, clinical trials and analyses of statin use, in which most study participants were male, had not shown an overall tendency toward increased violent death.
“We wanted to better understand whether and how statins might affect aggression.”
The researchers randomly gave more than 1,000 men and post-menopausal women either a statin (simvastatin or pravastatin) or a placebo for six months.
Neither researchers nor trial participants knew who was receiving the drug or the placebo.
Aggression was measured using a weighted tally of actual aggressive acts against others, self or objects in the prior week.
Other measurements taken included testosterone levels and reported sleep problems.
Prof Golomb said simvastatin is known to affect both measures, and both testosterone and sleep can affect aggression.
The results, published online by the journal PLOS ONE, showed that for post-menopausal women, the typical effect was increased aggression.
The effect was significant for post-menopausal women older than 45.
Doctors said the increase in aggression, compared to the placebo, appeared stronger in women who began with lower aggression before the trial. Prof Golomb said that the picture was more complex in men.
Three male participants who took statins displayed very large increases in aggression.
When the three were included in the analysis, they cancelled out an average drop in aggression.
But when they were removed from the analysis, the decline in aggressive behaviour for male statin-users was significant.
Prof Golomb said the effects were stronger among younger men who tended to be more aggressive, but he added: “Actually, the effect was most evident in less aggressive men.”
Prof Golomb said a full set of biological explanations linking statins to behaviour remains a “work in progress”.