"Keep calm and carry an aspirin to beat your temper," reports The Daily Telegraph's front page.
This risible headline comes from a study that did not look at aspirin or at people who have a "quick temper".
In fact, the study investigated whether people with a condition called "intermittent explosive disorder" (IED) had higher levels of two proteins that indicate inflammation.
Researchers compared people with IED to two groups of people who did not have aggressive outbursts – one group with a different diagnosis of mental illness and the other with no mental illness.
They found that levels of C-reactive protein (CRP) and interleukin 6 (IL-6) were significantly higher in people with IED. Higher levels of CRP and IL-6 in any group were also associated with increased levels of aggression.
But as this was a case-control study, it can only show that there is an association between these inflammatory markers and aggression. It does not tell us that inflammation causes aggression or that reducing the levels of inflammation would have any effect on aggression.
The study was carried out by researchers from the University of Chicago and the University of Colorado. It was funded by the National Institute of Mental Health and a grant from the University of Colorado, Denver.
The study was published in the peer-reviewed medical journal, JAMA Psychiatry.
The Telegraph coverage has made the huge and misguided assumption that simply taking aspirin could be the answer to both treating intermittent explosive disorder and calming people with a quick temper.
This was a case-control study looking at the level of two inflammatory markers in people with and without a history of aggression and impulsivity. This study can only show an association. We cannot tell whether aggression and impulsivity occur before or after inflammatory markers are raised merely from the results of this study.
Further research in the form of a randomised controlled trial would be required to determine whether aspirin or other anti-inflammatory drugs are effective treatments for intermittent explosive disorder or calming a quick temper, as suggested by the Telegraph.
Researchers measured the levels of two markers of inflammation in three groups of people to see if they were related to aggression and impulsivity.
Participants were recruited from clinical settings and through newspaper advertisements. People were excluded if they suffered from bipolar disorder, schizophrenia or mental "retardation". They were medically examined, screened for any drug abuse, and mental illness was diagnosed using the standard DSM-IV criteria (read more about the DSM).
The participants were put into three groups:
Eight standard questionnaires and a structured interview were used to assess:
Participants did not take any medication for at least four weeks and then had a blood test for C-reactive protein (CRP) and interleukin-6 (IL-6).
Statistical analyses were performed to look for differences between the groups and the levels of CRP and IL-6.
They also analysed the results to see if any of the following could account for any differences seen:
People with IED had higher inflammatory marker levels than either "healthy" controls or "psychiatric" controls. The results did not change when BMI, age, depression or recent psychological stress were taken into account.
People with IED and a current or previous mental illness or personality disorder had significantly higher levels than the "psychiatric" control group, and previous history of psychiatric treatment did not change these results.
Across all participants, higher levels of aggression and impulsivity increased the levels of CRP and IL-6, even after BMI, age, depression or recent psychological stress were adjusted for.
The researchers concluded that, "These data suggest a direct relationship between plasma inflammatory processes and aggression in humans."
This study showed that aggression and impulsivity were associated with slightly – but significant – increased levels of two inflammatory markers. It does not explain why this association is present.
There are a number of limitations of this study. These include:
Use of anti-inflammatory medication such as aspirin was not assessed in this study, and nobody should follow the Telegraph's advice to pop an aspirin if you've got a bad temper.