Some say it is harmful to bottle up anger.

Now evidence has been found that suppressing rage delays healing, suggesting that anger management courses could help wounded people to leave hospital sooner.

Earlier work showed how stresses hold up healing, from the chronic stress caused by caring for a parent with dementia to the burst of hostility caused by everyday events, such as a marital spat.

An American team has found that being unable to control and vent anger harms healing, according to a study published in the journal Brain Behavior and Immunity by Jean-Philippe Gouin and colleagues from The Ohio State University, Columbus, Ohio.

To see if anger would hold back wound healing, the team conducted a study with 98 participants who had agreed to receive standardised blister wounds, inflicted by a vacuum pump on their non-dominant forearm.

After blistering, the wounds were monitored daily for eight days to assess the speed of repair. The secretion of the stress hormone cortisol was also measured during blistering to evaluate the role of this stress hormone in the healing process.

Anger control was assessed using a standard scale and the participants were categorised as slow healers if they took more than four days to heal the standardised wound.

Taking into account potential confounding factors, people with low control over the expression of their anger were 4.2 times more likely to take more than four days to heal, compared to those with higher levels of anger control.

Individuals with low anger control exhibited greater cortisol production, which was in turn, associated with delayed healing.

"We found that individuals who were able to control the expression of their anger healed faster standardized wounds. Therefore, the variable of interest in our study is a characteristic of the individual, not of the environment," says Mr Gouin.


"For example, all the participants in our study were exposed to a blistering procedure evoking mild stress for the individual. However, not all participants responded in the same way to this standardized stressor. Those who had low anger control secreted more cortisol following exposition to this stressor. This individual difference in the response to the blistering was related to longer healing."

The authors state that these stress-induced delays in healing could increase the susceptibility to infection at the wound site and result in longer hospital stays.

"Past research has indeed showed that slower wound healing caused by stress increases the risk of infection at the wound site," says Mr Gouin.

This is "the first study showing that difficulty in anger regulation can lead to delayed healing".

Fortunately, says the team, relaxation and cognitive therapy offer a way to help individuals improve their anger control and it will go on to test the efficacy of this approach in future work.