Tuesday March 29 2011
People who took cortisol, a stress hormone, had lower anxiety levels
A study suggests “a pill could help people cure themselves of a fear of heights”, reported The Daily Telegraph. It said, “Scientists have discovered that giving people a tablet of the stress hormone cortisol can help reduce their phobia.”
This news story is based on a randomised controlled trial in 40 people with acrophobia (fear of heights). It compared the effect of cortisol against a placebo when given one hour before three sessions of virtual reality–based exposure therapy (a simulation of an elevator ride).
The researchers found that although both groups improved after the virtual reality therapy, people who also had cortisol rated their improvement as greater. Objective scores of anxiety (how much the participants sweated) also showed that those given cortisol showed less anxiety than the placebo group a month after the therapy sessions.
This preliminary study shows promising early results for this combined treatment. However, it is still early research in only 40 people. Follow-up studies are needed to replicate these findings and to gauge the extent of this effect. It will also be necessary to see if these results can be reproduced in more challenging real life situations.
Where did the story come from?
The study was carried out by researchers from the University of Basel, Switzerland, and other universities and institutions in Europe. Funding was provided by the Swiss National Science Foundation and the Basel Scientific Society.
The study was published in the peer-reviewed journal Proceedings of the National Academy of Sciences of the United States of America.
The research was generally covered accurately by The Daily Telegraph and the Daily Mail.
What kind of research was this?
This was a double-blind, randomised controlled trial. The researchers were interested in whether taking cortisol, a stress hormone, helps to relieve fear in people with a phobia of heights when combined with a behavioural therapy called exposure therapy.
Exposure therapy is a behavioural therapy technique in which people with phobias, in a limited and structured manner, are exposed to their fears after being shown different relaxation and coping techniques, aimed at decreasing the intensity of their fear response. In this study, to prepare the participants for the exposure, they were given educational materials about exposure therapy and instructions on how to cope with their former avoidance strategies during the pre-treatment assessment. However, no cognitive behavioural techniques such as breathing or relaxation techniques were used.
Cortisol is a stress hormone released from the adrenal gland. It has many functions, including increasing blood sugar, but it is also thought to affect learning and memory processes. Cortisol is a type of hormone called a glucocorticoid. Previous animal research using other glucocorticoid hormones has shown them to be effective at promoting ‘extinction processes’ (lessening of fear during exposure to a fear-inducing stimulus). Therefore, the researchers wanted to see whether glucocorticoids could be useful in enhancing exposure therapy in humans.
A randomised double-blind placebo controlled trial is the best method of assessing whether a treatment is effective for a condition.
What did the research involve?
The study recruited 40 people who had a specific phobia of heights (acrophobia), which was defined according to psychiatric criteria listed in the Diagnostic and Statistical Manual of Mental disorders, Fourth Edition (DSM-IV).
The participants were given three sessions of exposure therapy using virtual exposure to heights. Virtual reality exposure to heights has been shown to be effective for treating people with acrophobia. One hour before each session, half the participants were given a cortisol pill, while the other half were given a placebo pill. Neither the participants nor the person giving them the pills knew which pills were placebos.
Three to five days after the last treatment session, the participants had a post-treatment session and were assessed once more a month later. These post-treatment assessments were compared to assessments made before the treatment had commenced.
The success of the treatment was assessed by giving the participants questionnaires in which they were asked to rate how fearful they felt when considering 20 situations that could cause fear of heights. Examples of these situations include driving over a bridge or sitting on an aeroplane. Participants were asked to rank these on a seven-point scale. The questions also asked about the possible consequences of scenarios involving heights. This was to assess the participants’ attitude to heights, and the likelihood that they would avoid being in a scenario involving heights, or their behaviour in such a scenario.
The participants were also asked about their anxiety levels during virtual reality therapy and during a real life situation involving height (going up an outdoor staircase with three levels). During the real life test (Behavioural Avoidance Test), participants were given one point for each level they climbed and one point for looking down for 30 seconds at each level.
As a more objective measure, fear was estimated using the ‘skin conductance response test’. This test measures the moisture levels on the skin. It is used to measure fear as the skin produces sweat in response to stress.
What were the basic results?
The researchers found that, based on their scores on the acrophobia questionnaire, all of the participants benefited from the virtual reality therapy for acrophobia. The participants who also had cortisol however, showed a significantly greater improvement at post-treatment and at one month follow-up (p=0.031).
The researchers used a statistical technique called Cohen’s d to calculate the difference between the average (mean) “effect size” of the cortisol pills compared to the average effect of the placebo. This technique calculated the difference to be somewhere just over a ‘medium effect’ at d=0.6 for the effect size at both post-treatment and one month follow-up. For this d statistic, a value of 0.2 to 0.3 is considered to be a “small” effect. Around 0.5 is a “medium” effect, and more than 0.8 is a “large” effect.
Cortisol was also found to decrease “danger expectancy” at follow-up (effect size, d=0.6). However, the researchers did not find a difference between the cortisol and placebo groups on the attitude toward heights questions and on the behavioural avoidance test.
At the post-treatment session, the cortisol group had lower levels of anxiety during the virtual reality height exposure according to subjective measures of discomfort (SUD) in which the participants were asked to rank their anxiety from 0 “no anxiety at all” to 100, “extreme anxiety”. This difference was not maintained at follow-up one month later.
The objective measure of anxiety, the skin conductance test, showed that the cortisol group had a smaller exposure-induced increase in sweat compared to the placebo group at follow-up. However, due to technical reasons, the researchers were only able to collect skin conductance data from 25 of the participants at one hour post-treatment (11 from the placebo group, 14 from the cortisol group) and from 20 participants at follow-up (9 from the placebo group and 11 from the cortisol group).
How did the researchers interpret the results?
The researchers said that cortisol enhances the effect of virtual reality exposure therapy for people with a fear of heights as assessed by the acrophobia questionnaire - a standard questionnaire used to assess fear of heights.
They call for further studies “to investigate the cortisol effects in more challenging real-life situations”. They say that studies which look at pharmacological or behavioural treatments that enhance extinction or reconsolidation of fears after therapy may “not only help to better understand the role of memory processes in fear reduction but may also contribute to the development of novel therapeutic strategies to treat anxiety disorders”.
This study shows that cortisol treatment prior to virtual reality exposure therapy sessions for acrophobia can have a beneficial effect compared to placebo with virtual reality exposure. The researchers also point out that virtual reality-based exposure therapy for fear of heights has been shown to be effective. This is supported by this study.
However, this was a small preliminary study with only 20 people in each group (and only data for 25 people using the only objective measure of anxiety, the skin conductance test). Further research is needed to assess optimum treatment programmes and the safety and effectiveness of cortisol in addition to long-term behavioural therapy.
As the participants had a psychiatric diagnosis of acrophobia, it is not clear whether this study is relevant to people with less severe fear of heights. The researchers also say that it is necessary to see if the results seen in this study can be reproduced in more challenging real life height situations.