Medical Bulletin 13/January/2024

Here are the top medical news of the day:

Watching others visibly dislike vegetables might make onlookers dislike them, too

Humans learn which behaviors pay off and which don’t from watching others. Based on this, we may draw conclusions about how to act – or eat. In the case of the latter, people may use each other as guides to determine what and how much to eat. This is called social modelling and is one of the most powerful social influences on eating behavior.

In a new study, researchers in the UK investigated whether observing others’ facial expressions while eating raw broccoli influenced young women’s liking and desire to eat raw broccoli.

“We show that watching others eating a raw vegetable with a negative facial expression reduces adult women’s liking of that vegetable, but not their desire to eat it,” said Dr Katie Edwards, a researcher at the Aston University School of Psychology and lead author of the study published in Frontiers in Psychology. “This highlights the power of observing food dislike on adults’ eating behavior.”

In the study led by Edwards, just over 200 young women watched a video containing clips of different unfamiliar adults consuming raw broccoli. While eating, the models displayed positive (smiling), neutral, or negative (disgust-like) facial expressions. The researchers examined only women’s reactions since gender differences may exist within the modelling of eating behavior, and modelling effects can be different among women and men.

One possible explanation may be that avoiding any food – irrespective of whether it is commonly liked or disliked – that appears disgusting can protect us from eating something that tastes bad or is harmful. Another reason may be that smiling while eating is perceived as an untypical display of liking a certain food. “This might imply that watching someone eating a raw vegetable with positive facial expressions does not seem an effective strategy for increasing adults’ vegetable consumption,” said Edwards.

Reference: Watching others visibly dislike vegetables might make onlookers dislike them, too; Frontiers in Psychology, DOI: 10.3389/fpsyg.2023.1252369

Nationwide study suggests link between medical cannabis for chronic pain and abnormal heart rhythm

People taking medical cannabis for chronic pain have a slightly increased risk of arrhythmia, according to research published in the European Heart Journal today (Thursday). Arrhythmia is when the heart beats too slowly, too quickly or irregularly. It includes conditions like atrial fibrillation.

Recreational use of cannabis has been linked to cardiovascular disease but there has been very little research on the side effects of medical cannabis.

Researchers say the new study is important as a growing number of countries now permit medical cannabis as a treatment for chronic pain.

The study was led by Dr. Anders Holt from Copenhagen University Hospital – Herlev and Gentofte in Denmark. It included data on 5,391 Danish patients who had been prescribed cannabis for chronic pain. This included people with pain in their muscles, joints or bones, people with cancer and those suffering with nerve pain. Researchers compared this group with 26,941 patients who also had chronic pain but were not receiving cannabis as a treatment.

The data showed that patients receiving medical cannabis had a 0.8% risk of being diagnosed with arrhythmia that required monitoring and possible treatment within 180 days of receiving cannabis. This risk was more than twice the risk for patients with chronic pain who were not taking cannabis. The difference in risk between the two groups had become smaller when researchers looked at the first year of treatment.

Patients taking cannabis who were aged 60 and older and those already diagnosed with cancer or cardiometabolic disease, such as heart disease, stroke and diabetes, had the largest increases in their risk of arrhythmia.

The study did not show any link between taking medical cannabis and the risk of acute coronary syndrome, which includes a heart attack and unstable angina, stroke or heart failure.

Researchers say this is the first nationwide study of its kind investigating the cardiovascular effects of medical cannabis for chronic pain. However, they caution that this is an observational study. Dr. Holt explained: “Despite our best efforts to make a balanced comparison, it can never be assumed that patients prescribed medical cannabis do not differ from patients not prescribed medical cannabis, and this could influence the results.”

Reference: Nationwide study suggests link between medical cannabis for chronic pain and abnormal heart rhythm; European Heart Journal, DOI: 10.1093/eurheartj/ehad834

Perinatal depression linked to increased risk of death

Women who suffer depression during or after pregnancy have a higher risk of death by both natural and unnatural causes, a new study of childbirth in Sweden published in The BMJ reports. The increased risk peaks in the month after diagnosis but remains elevated for as long as 18 years afterwards.

Women who develop perinatal depression, which is to say depression during pregnancy or shortly after childbirth, are generally twice as likely to die of natural or, as in most cases, unnatural causes.

These are the results of a large cohort study that used data from the Swedish Medical Birth Register, which effectively contains all births in Sweden since 1973.

Basing their study on women who had live births between 2001 and 2018, the researchers compared over 86,500 women diagnosed with perinatal depression, during pregnancy or up to one year after childbirth, with over 865,500 matched controls of the same age who had given birth the same year.

“This is a cohort study, and although it can’t prove any causality, it’s the largest and most comprehensive study in its field,” says Qing Shen, affiliated researcher at the Institute of Environmental Medicine, Karolinska Institutet and one of the principal authors of the study. “I believe that our study clearly shows that these women have an elevated mortality risk and that this is an extremely important issue.”

The risk was highest for the women diagnosed with postpartum depression (depression after childbirth), corroborating the findings of previous smaller studies. Women diagnosed with antepartum depression (depression during pregnancy) have not been studied as much, so the knowledge base there is smaller. Dr Shen and her colleagues can now show that women with antepartum depression also have an elevated mortality risk, albeit not as high.

Reference: Perinatal depression linked to increased risk of death; BMJ, DOI:10.1136/bmj-2023-075462