Scientists say despite theories, there is no link to depression and any type of cancer.
A recent study of more than 300,000 adults, found that neither depression nor chronic anxiety contributes to an increased chance of developing cancer. In fact, when researchers looked at specific types of cancer, the findings were largely the same.
However, the research indicated that smoking — as well as alcohol and heavy body weight — are the real culprits, rather than depression or anxiety themselves.
The study was published in the journal Cancer. The findings perhaps offer reassurance to people who have routinely blamed a cancer diagnosis on their mental health struggles.
“Our findings show that there is no evidence for this,” said study leader Lonneke van Tuijl, a health psychology researcher at University Medical Center Groningen in the Netherlands.
Unfortunately, that kind of self-blame “comes up a lot,” said Dr. William Breitbart, chief of psychiatry at Memorial Sloan Kettering Cancer Center in New York City.
“There are many patients who feel guilt, who say ‘I gave this to myself,'” said Breitbart, who was not involved in the study.
The reality, he said, is that cancer is many different diseases, each caused by a complex interplay of genes and environment.
There has been a decades-old interest, though, in the question of whether daily stress, depression or even a less-than-sunny personality might help cause cancer, Breitbart noted.
Over the years, that has included studies suggesting that having a “fighting spirit” or “positive attitude” helps people survive cancer.
“We called it the tyranny of positive thinking,” Breitbart said. “It was a real thing, and it still is.”
While the National Institutes of Health states that major depression is a very common disabling disorder. NIH also reveals that the relationship between race and depression is complex, stating that while depression affects all races, all ethnic and geographic locations as well as all age group, the occurence of depression in African Americans can be controversial because of the lack of scientific research. In fact, scientists say because of insufficient research, treating depression in African Americans has not been adequately addressed.
However, the prevalence of depression in African Americans is reported to be twice as compared to whites.
There is a logic to the idea that depression or anxiety disorders could increase the risk of cancer. The conditions are linked to heightened odds of certain other physical health ailments, like heart disease. In that case, researchers believe the connection might partly be due to stress hormones on the cardiovascular system.
But when studies have delved into the question of whether depression and anxiety are linked to cancer risk, the findings have been “all over the place,” Breitbart said.