Individuals who are highly sensitive to environmental stimuli – highly sensitive people – appear to be more susceptible to substance use than others. Nevertheless, there has been very little scientific research on the relationship between high sensitivity and the use of addictive substances. The ERANID STANDUP project should change all that, however.
Project leader Dr. Judith Homberg of Radboud University in Nijmegen, the Netherlands, says that people with a high Sensory Processing Sensitivity score – i.e. people who are highly sensitive – also experience above-average problems with stress. ‘This is not surprising,’ Dr. Homberg explains. ‘These people notice all kinds of subtleties around them, respond to them and process this information at a deeper level in their brains.’ If the brain receives too many (negative) stimuli, it can no longer process them, and that produces stress. Approximately 20% of adults are highly sensitive.
Homberg explains that it is precisely this stress factor that makes them more susceptible to addictive substances. ‘Drugs are an escape, a way of coping with all the stuff going on in their heads. Just think of performers and artists. Highly sensitive people are often exceptionally creative, and in those circles you also see excessive use of addictive substances.’ A relationship between high sensitivity and substance use has never really been scientifically proven, though there is a range of evidence that point to such a connection.
Homberg finds it surprising that no extensive scientific study has examined this link. ‘In that respect this research could probably be called groundbreaking. This will be the first in-depth study on this topic. It could be that among users there are more than the average 20% highly sensitive people. What’s more, highly sensitive people have very specific characteristics. This means we might need to help them fight their addiction in a completely unique way.’
The study will be performed in collaboration with teams in Italy, Switzerland and France. Homberg is very pleased with this joint approach. ‘I can now work with leading international scientists. By collaborating we can share knowledge and facilities, complement each other’s efforts. Furthermore, the results of the study will be made widely available in Europe, so they will not only benefit the Netherlands, but also other countries.’
Switzerland and France have large ‘cohorts’: groups of addictive substance users who take part in scientific studies. ‘There are no such cohorts in the Netherlands, so that in itself is a benefit’, says Homberg. Thanks to the ERANID project, new questions on high sensitivity personality will be incorporated into research. This should make it clear whether and to what extent high sensitivity personality is indeed a factor in substance use.
Homberg is working on an animal model using rats. It has been found that animals, too, can be highly sensitive, which widens the potential for research. However, this will require a good research model that allows highly sensitive rats to be reliably distinguished from ‘ordinary’ rats. This means rats have to be screened on the basis of certain behavioural criteria.
Italy will study blood and brain samples – blood samples from people and brain samples from animals. In this part of the study, Homberg’s Italian counterparts will look for specific biomarkers that can be linked to changes in drug use under the influence of environmental stimuli in highly sensitive people and animals. ‘What we already know is that in highly sensitive rats nerve cells in the brain that respond to external stimuli are less inhibited than in rats with low sensitivity, which causes them to “fire” more often than average’, Homberg explains. ‘It would be fantastic if we could use biomarkers to draw parallels between changes in behaviour and brain function.’
Eventually, Homberg hopes all the research will lead to a therapy for highly sensitive people who use substances. ‘The good thing about high sensitivity personality is that it is not only associated with sensitivity to negative stimuli, but also to positive ones. Think of things like romantic relationships, having children or finding a new job – so the good things in life.’ The researchers will explore whether exposure to such environmental stimuli, and which ones precisely, leads to a reduction in drug use in highly sensitive people. In order to develop a therapy that ensures that more attention is focused on positive stimuli Homberg is working with various stakeholders, both psychologists and people who have personal experience with the issue.
Judith Homberg hopes that the ERANID study will help reduce the stigma of addiction. Many people equate addiction with weakness. ‘But if addiction and high sensitivity personality are linked,’ she says. ‘Then for some people addiction would be a side-effect of other, positive qualities.’ Addiction as the flipside of creativity, in other words.
The European Research Area Network on Illicit Drugs (ERANID) aims to improve cooperation in drug research in order to allow well-founded policy decisions, prevention and harm reduction interventions. Several scientific disciplines and various European countries work together in this network. ZonMw is one of the partners in the cooperation on behalf of the Netherlands and is coordinator of ERANID.