No proof found that depression is 'contagious'
'Can you catch depression?', the Mail Online website asks on the strength of new US research into the concept of 'cognitive vulnerability'.
Cognitive vulnerability is where unhelpful patterns of thinking can increase the risk of a person developing conditions such as depression. The researchers in this study were interested in the idea that cognitive vulnerability may be 'contagious'.
The study followed roughly 100 pairs of roommates at a US university for the first six months of their freshman (first) year. They wanted to see if one student's cognitive vulnerability might influence the cognitive vulnerability of their new roommate.
They found that students who shared a room with a person with higher cognitive vulnerability (theoretically more susceptible to depression) were more likely to show an increase in their own cognitive vulnerability three and six months later.
However, this short-term study does not prove that depression can be 'spread' – only one measure of cognitive vulnerability found that a roommate can influence another's mental health in a negative way.
The study did find that students who showed increases in cognitive vulnerability at three months were more likely to experience increased symptoms of depression at six months. But importantly, if one roommate became more depressed, the other roommate showed no change in their depressive symptoms.
Where did the story come from?
The study was carried out by two researchers from the department of psychology at the University of Notre Dame in the US. No sources of financial support are reported. It was published in the peer-reviewed journal Clinical Psychological Science.
Despite Mail Online's headline, this research did not prove that you can 'catch depression'. The study actually looked at whether you can 'catch' cognitive vulnerability, which may or may not put you at increased risk of later depression.
Students were also not found to be at risk of experiencing increased symptoms of depression during follow-up just because their roommate's depression symptoms had increased.
What kind of research was this?
The researchers report that depression may theoretically develop through risk factors such as 'cognitive vulnerability'. The theory is that people have patterns of thinking that effect how they experience and respond to stressful life events.
Some people may have particular patterns of thinking that make them less able to cope with negative experiences. This can then lower their mood and have a detrimental effect on their feelings of self-worth. These people are described as having cognitive vulnerability to depression.
The researchers say that past observational studies have shown that cognitive vulnerability interacts with stressful events to predict the development of depression. Therefore, they say it is valuable to understand whether a person's level of cognitive vulnerability is relatively stable and stays the same throughout their life.
Alternatively, it could also be possible that cognitive vulnerability is influenced by environmental factors – in other words, you can 'catch' a higher level of cognitive vulnerability from others.
This study aimed to test the theory that cognitive vulnerability can be contagious. The researchers suspected that transitions in people's social lives, such as moving away to a new area or starting college, can have a significant effect on cognitive vulnerability, and that this feeling can be passed on to others.
To test this, the researchers took advantage of the routine US practice where freshmen university students (first years) share on-campus university accommodation with a randomly assigned roommate. They wanted to assess what effect this randomisation had on people's levels of cognitive vulnerability and related symptoms of depression and anxiety.
The researchers' main prediction was that cognitive vulnerability would be contagious between roommates – if one had increased vulnerability, so would the other.
However, the problem with this study's design is that its ingenuity in making use of the US 'roomie' system is also an inherent limitation. The population studied (first-year university students sharing rooms) is very specific, so the findings may not apply to other groups.
Also, moving away from home for the first time to start university involves many life changes. This makes it more difficult to see which factors have a psychological effect on people.
What did the research involve?
The research included 103 college freshman roommate pairs (42 male pairs, 66 female pairs, 80% white ethnicity) from a "selective, private, mid-sized" university in the midwestern United States.
The sample was initially recruited by randomly selecting freshmen from a directory and emailing them to see if they and their roommate were happy to complete the questionnaires.
The research says that all freshmen at this university are required to live in an on-campus dormitory, and are randomly assigned to both a roommate and a dormitory by computer.
Within one month of arriving on campus, freshmen who agreed to participate in the study completed baseline questionnaires. They then completed these questionnaires again three months and six months later. The questionnaire assessed three main areas associated with cognition and mental health.
Cognitive vulnerability
The researchers measured cognitive vulnerability factors, as defined by two main cognitive theories on depression: the 'response style' and 'hopelessness' theories.
Response style theory defines cognitive vulnerability as the tendency to focus attention on your negative mood and dwell on the implications of that mood. Essentially, this is how well participants can cope and distance themselves from negative moods or not – the difference between "I'm feeling a bit low today, but I am probably just a bit out of sorts" and "I feel miserable because I am worthless". This was measured using a well-validated questionnaire.
Hopelessness theory defines cognitive vulnerability as the tendency of an individual to draw particular kinds of conclusions about the cause, consequences and self-worth implications of negative life events. This is the difference between believing "things can only get better" and "bad things are going to continue to happen to me for the rest of my life". This was measured by assessing participants' inferences from 12 hypothetical negative events.
Stressful life events
The participants took the acute life events questionnaire. This assesses 30 naturally occurring acute stressful life events important to college students, ranging from achievement to interpersonal effects.
Depression symptoms
This was assessed using the Beck Depression Inventory, a widely used self-assessment of depression.
The researchers used modelling techniques to look at a person's cognitive vulnerability over time, from the first assessment to three and six months later. They looked at whether this was also related to their roommate's vulnerability. They adjusted for depression and stressful life events measured on the first questionnaire.
What were the basic results?
All participants completed the baseline questionnaires and 90% completed at least one of the two follow-up questionnaires.
Cognitive vulnerability was relatively stable over follow-up, with an individual's level of cognitive vulnerability at baseline being a strong predictor of their vulnerability at three and six months.
Individuals' cognitive vulnerability was also influenced by their roommate's baseline vulnerability, as measured by the response style questionnaire. People who were randomly assigned to a roommate with a high level of cognitive vulnerability at baseline experienced increases in their own level of cognitive vulnerability over time.
Meanwhile, people assigned to a roommate with low baseline levels of cognitive vulnerability experienced decreases in their levels of cognitive vulnerability over time. These associations remained even after adjusting for the pair's depression and stressful life events at baseline.
However, there was no 'contagion effect' of cognitive vulnerability at three or six months, as measured by the hopelessness questionnaire.
The researchers then tried to look at a person's future risk of developing depression by seeing whether increases in cognitive vulnerability from baseline to three months predicted the level of depressive symptoms at six months.
They found that people whose cognitive vulnerability increased during the first three months of college had greater levels of depressive symptoms at six months than individuals who did not experience an increase in cognitive vulnerability.
Importantly, however, there didn't seem to be a contagious effect of depression symptoms. A person was not at risk of experiencing depression symptoms during follow-up just because their roommate's depression symptoms had increased.
How did the researchers interpret the results?
The researchers say that the results of their study support the hypothesis that cognitive vulnerability can be contagious. Freshmen who were assigned to a roommate with high levels of cognitive vulnerability were found to be "likely to 'catch' their roommate's cognitive style and develop higher levels of cognitive vulnerability". An increase in cognitive vulnerability was then associated with an increase in depression symptoms during follow-up.
Conclusion
This study suggests that it is possible that one roommate's cognitive vulnerability can influence the other's. However, it can only provide a limited insight into which factors influence cognitive vulnerability – the way a person experiences and responds to stressful events – and whether this influences future risk of depression.
Only a relatively small sample of US students was examined in the very specific scenario of the first six months of starting university. Starting university involves many life changes. Because of this, it is very difficult to conclude from this study that cognitive vulnerability is contagious, or say how much increases in a person's vulnerability were due to the roommate's vulnerability.
There are likely to be many biological and environmental factors that could have an effect on an individual's cognitive vulnerability, rather than it simply being the effect of a roommate's cognitive vulnerability.
While researchers did take into account the students' levels of depressive symptoms and stressful events at the start of the study, this still cannot discount the complex effects that starting university can often have on a person's mental health and wellbeing.
Overall, the study will be of interest to the field of psychology, but on its own it does not provide conclusive evidence that cognitive vulnerability or depression are 'contagious'.
