New research published in the Lancet journal has revealed that people with depression are about three times more likely to commit a violent crime than someone who is not depressed.

This is an impressive study – based on 47,000 Swedish people – but we need to be extremely cautious about how we interpret the results. The research shows that extremely few depressed people are actually convicted of violent crimes: 3.7% of men and 0.5% of women, compared with 1.2% of men and 0.2% of women in the general population. In fact, depressed people are more at risk of harming themselves than they are of harming anyone else – like Charlie Waller, a young man who killed himself aged 28 and whom the institute I work at is named after.

It is also important to understand that this study shows an association between convictions and depression. Depression doesn’t cause convictions, and likewise convictions don’t cause depression. Many other factors can explain the association. These include previous traumatic experiences, such as violence towards oneself, poverty and social deprivation, and inadequate care as a child. The researchers in this study have done a very good job of controlling some of these – but this can only ever be partially successful.

This study does not show that depressed people commit more crimes. It means they were caught and found guilty more often than people who were not depressed. They may have committed fewer crimes or the same number of crimes, we just don’t know, and this data can’t tell us.

How is it possible that depressed people are convicted more often if they might not have committed more crime? Depression is associated with hopelessness, apathy, sadness and feelings of guilt. It is more common in those who have lower incomes, the unemployed and those who are excluded from mainstream society. People who are depressed may be more hopeless, feel that they deserve to be punished and are therefore less likely to try to avoid being caught.

When accused of a violent crime, depressed people may also be more likely to be charged with that crime. On average, people who are depressed may make less effort to avoid punishment, and may be more ready to admit to having committed an offence. And as depression is more common among those with lower incomes, it may be harder to access good legal advice, increasing the chances of being found guilty. Low mood and a lack of energy and motivation, along with a sense of inner guilt and the expectation of punishment, may all contribute to the chances of a judge or jury convicting them.

Also, depressed people may be even be more likely to admit to offences they did not commit because they feel deserving of punishment, and are more susceptible to pressure to confess.

This is an important piece of research but it is imperative that we treat the results with care. We must not use them to increase the stigma attached to depression or reduce the compassion we feel for those living with it.