Last week DISCOVER brought you the sad and somewhat counter-intuitive study that suggested loneliness could actually be “contagious” and spread across a social network. Now more bad news for the lonely. In a study (in press) in the Proceedings of the National Academy of Sciences, another team of researchers argues that, in rats at least, loneliness can increase cancer incidence.
The scientists separated their test rats at birth, keeping them either in groups of five or alone. Those kept alone had a 135% increase in the number of mammary tumours, a 8,391% increase in the size of tumours and a 3.3-fold increase in the relative risk of malignancy [Nature News]. They also showed higher levels of the hormone corticosterone, which is connected to stress.
The researchers note that these early findings were done with just 40 rats in total. And the connection of stress and breast cancer can’t yet be translated to humans, says researcher Ed Yong. “But it’s possible that stressful situations could indirectly affect the risk of cancer by making people more likely to take up unhealthy behaviours that increase their risk, such as overeating, heavy drinking, or smoking” [BBC News].
Indeed, the stress from being alone is the main suspect in these normally social Norway rats’ increased cancer risk, lead researcher Gretchen Hermes says, and scientists have seen the detrimental health effects that badly managed stress can have on people. “The effects are equal to or greater than the effects of cigarette smoking—that includes a significantly shortened life span” [ABC News].
Related Content:
80beats: Sad and Ironic Study Says Loneliness Can Be Contagious
DISCOVER: Why Loneliness Is Bad For You
DISCOVER: Will Loneliness Spell Society’s Doom?
Image: iStockphoto
December 9th, 2009 at 3:13 pm
I feel so bad for the poor lonely rats…
December 10th, 2009 at 5:56 am
its nice to see this sort of discussion but you must keep in mind
I think that this case is also same for human.
December 10th, 2009 at 11:56 am
Forty rats aren’t enough to base a conclusion on. Even if the stats hold out, the only way to eat one is skewered, over a fire.
December 14th, 2009 at 9:14 pm
Interesting. I have had about 10 rats as pets over the years. All of them were classroom pets except one. They all died of huge tumors by the time they were 2 years old (I eventually put each one to sleep) except the one that I kept at home alone. He lived to be 3 years old and no huge tumors – anecdotal evidence, but interesting. Maybe the stress of school and kids was the bane of the others.
December 15th, 2009 at 10:38 am
Interesting study and interesting results. Would a study be possible to include the difference between lonely and alone? You suggested these rats are normally social.
I see a real difference in the emotional state of those I meet who are lonely, even in a crowd, and those who are alone but don’t seem downtrodden by lonliness.