"Being married can make you depressed, study finds," The Independent reports. Perhaps a more accurate summary of the research the paper reports on is "being unhappily married is associated with different responses to positive pictures" (admittedly, not such a catchy headline).
The study involved married and cohabiting couples who were assessed twice over a nine-year period. Assessment involved looking at electrical activity produced by the corrugator muscle, or "frowning muscle", in response to positive, neutral and negative pictures. This muscle contracts in response to negative images and relaxes in response to positive images.
The study found that higher levels of marital stress were associated with the electrical activity in the frowning muscle returning to normal faster after participants were shown a positive image.
The implication – at least according to the researchers – is that marital stress may have a negative impact on people's capacity to enjoy or respond meaningfully to positive events in their life, and this may make them vulnerable to depression.
To be frank, it is difficult to see what practical applications – if any – this study has.
If you are having relationship problems, couples counselling – rather than having the electrical activity in your corrugator muscle analysed – is probably the best way forward.
The study was carried out by researchers from the University of Wisconsin-Madison and Swarthmore College in the US, and the University of Reading in the UK.
It was funded by the National Institute on Aging, the National Institute on Mental Health, the Waisman Intellectual and Developmental Disabilities Research Center, the National Institute of Mental Health Conte Center, the John Templeton Foundation, and the John D. and Catherine T. MacArthur Foundation Research Network on Successful Midlife Development.
The study was published in the peer-reviewed journal, Psychophysiology.
This study was widely reported in the media, with headlines implying that marriage was associated with depression. This is an incorrect interpretation of the findings. There is actually a wide body of evidence that being married improves mental health, as long as the marriage is (mostly) functional.
The study looked at levels of marital stress and found that higher levels of marital stress were associated with shorter muscle responses to positive images.
This cross-sectional study aimed to determine whether long-lasting marital strain is associated with electrical activity in the frowning muscle as part of a laboratory-based emotion study.
Although the researchers tried to adjust for depression, because this is a cross-sectional study we can't exclude the possibility that there are other factors (confounders) that are responsible for the association seen.
Also, because electrical activity in the frowning muscle was only measured at one point in time, we don't know whether marital stress caused it to change or whether it was always different.
As far as we know, there is no validated evidence that shows that changes in electrical activity in the frowning muscle are a proven sign of depression.
The researchers analysed data on 116 people who were either married or cohabiting and had participated in the Midlife in the United States study (a cohort study on health and well-being), who then agreed to take part in a laboratory-based emotion study.
As part of the Midlife in the United States study, people reported their experienced levels of marital stress on a six-item questionnaire, which assessed the frequency (never, rarely, sometimes, often) that a participant's husband or wife was a source of:
Higher scores were said to reflect higher levels of marital stress.
Participants completed the questionnaire twice, on average nine years apart. The researchers averaged the scores to obtain a measure of chronically experienced marital stress.
The laboratory-based emotion study was performed more than two years later. In the study, participants viewed a total of 90 colour images in a random order: 30 positive images, 30 negative images, and 30 neutral images. Pictures were shown for four seconds and a blank screen was then shown for between 14 and 18 seconds.
While the participants viewed the images, the electrical activity produced by the corrugator muscle, or frowning muscle, was measured by electromyography. Electromyography is a technique used to measure electrical activity in the muscles.
The researchers looked at electrical activity in three phases: the four seconds while the picture was being shown, one to four seconds after the picture was removed, and five to eight seconds after the picture was removed.
After the emotion study was finished, some participants also reported how attractive or aversive pictures were, and how reactive they felt in response to the images.
The researchers then analysed how chronically experienced levels of marital stress affected electrical activity in the frowning muscle in the three phases, and how attractive or aversive participants found the pictures.
Electrical activity in the frowning muscle was positive when participants were shown negative images, and negative when shown positive images, as a result of the muscle relaxing.
The researchers found that greater levels of marital stress were associated with short-lived frowning muscle electrical responses to positive images.
Levels of electrical activity were different in the five to eight seconds after the picture was removed. This association remained after the researchers controlled for depression.
There was no difference in muscle electrical activity responses to negative images.
The researchers concluded that, "Marital stress is associated with short-lived responses to positive pictures … these results suggest that social stress may impact health by influencing the time course of responding to positive events."
This study has found that higher levels of marital stress were associated with the electrical activity in the frowning muscle returning to normal faster after participants were shown a positive image.
Contrary to the media headlines, this study did not find that marriage causes depression. It also did not show how a person who had experienced marital stress would react to a positive experience. The most it can say is that marital stress is associated with shorter responses to positive images.
However, there may be other reasons that could account for these results and, as the image experiment was only performed once, it is not known whether the response time would have been the same prior to any marital stress.
The hypothesis that being in an unhappy relationship causes emotional upset is plausible and arguably did not need to be tested in this fashion.
If you are concerned about the state of your relationship, couples therapy is an option. The charity Relate can provide more information about what help is available.