Washington: Statins, a highly popular class of drug used to manage blood cholesterol levels and reduce the risk of heart disease, have been found to trigger anger among women, says a new study.

Previous studies had raised questions about adverse behavioural changes with statins, such as irritability or violence, but findings with statins have been inconsistent.

'Many studies have linked low cholesterol to increased risk of violent actions and death from violence, defined as death from suicide, accident and homicide,' said lead author Beatrice A. Golomb, professor of medicine at the University of California, San Diego School of Medicine

When placed on statins, the aggressive behaviour typically declined among men, but typically increased among women placed on statins.

The team wanted better understand whether and how statins might affect aggression. Researchers randomly assigned more than 1,000 adult men and postmenopausal women to 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. Behavioural aggression of the participants was measured using a weighted tally of actual aggressive acts against others, self or objects in the prior week.

For postmenopausal women, the typical effect was increased aggression. The effect was significant for postmenopausal women older than age 45. The increase in aggression (compared to placebo) appeared stronger in women who began with lower aggression at baseline.

'Either men or women can experience increased aggression on statins, but in men the typical effect is reduction,' Golomb said.

The findings were published in the online issue of Plos One.