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Tuesday, April 28, 2015

Neuroscience Blues: Study Finds That Thinking Can Fuel Tumor Growth - Not really!

"Neuroscience Blues," are posts where I critique the science behind an article in popular media, like from CNN, Fox, or in this case, The Huffington Post.

"Senior Writer" at the Huffington Post, Carolyn Gregoire* posted an article yesterday with the headline: Thinking Can Fuel The Growth Of Brain Tumors, Study Finds.

There is no evidence that human thought will cause
or contribute to brain tumor growth.
In the article, she writes that, "Thinking helps fuel the growth of deadly brain tumors, according to a surprising new study from Stanford University School of Medicine." Apparently, neurologist, Dr. Michelle Monje, the study's lead author, emailed this and other conclusions to Gregoire.

I could write several posts like this each day because there's so many spurious neuroscience "conclusions" posted online, but this one really caught my eye. I suspect that HuffPost writer, Gregoire didn't read the article herself, and health news consumers should be aware that a neurologist is not an immunologist, and it seems clear to me that immunological processes were not fully considered when drawing conclusions from this study.

Using mice in cancer research is old and common, but using mice in the manner described in this study (quoted text follows) is more complicated than usual cancer studies: 

     To conduct the study, Monje’s team employed optogenetics, a Stanford-developed technique that uses genetic manipulation to insert light-sensitive proteins into specific neurons, allowing the neurons to be activated with the flip of a light switch. Into the cerebral cortex of mice with these light-sensitive proteins, the team implanted cancer cells from a human pediatric cortical glioblastoma. After the tumors became established, neurons near the tumors were activated with light. The team then compared tumor growth between these mice and a control group with implanted tumors but without the nerve activation. Increased tumor proliferation and growth in the mice that received neurostimulation via optogenetics were the first indications that neuronal activity fed the brain tumors.

To summarize: cancer cells from a human, pediatric cortical (brain) glioblastoma were implanted in a mouse and then stimulated with optogenetics, and those cancer cells near to optogenetic stimulation proliferated (grew) more than the the cells without optogenetic stimulation.

So, the best conclusion to draw from this study would be: 
Specific human tumor cells implanted in a mouse grow faster 
when stimulated with optogenetics than human tumor cells in a mouse that are not stimulated by optogenetics.


Could this mean that human "thinking fuels" tumor growth? No, not even close. Normal human mental processes that occur in the environment of human brain and body, that are stimulated (or not) using optogenetics have not been studied. So, no one should conclude that human thinking, that occurs in a human brain environment, would fuel tumor growth.

What the study did find is that there appears to be a protein that is released during artificially stimulated mental activity that appears to stimulate glioblastoma tumor growth. Whether or not this occurs in the environment of the human brain has yet to be seen. A drug that inhibits Neuroligin-3 may help decrease tumor growth in humans; but it may take many years to produce a drug that can effectively and safely achieve this; but in the end, they may find that suppressing Neuroligin-3 proteins has no effect on human tumor growth.

So, for anyone suffering from hypochondria or "medical student's disease," put your mind at ease, you're not going to get cancer from thinking too much, and it's highly unlikely that "thinking" will cause a tumor to grow, even if you had a tumor (which you most likely don't). On a side note: thinking does cause an increase in activity in one part of the brain while simultaneously causing a decrease in activity in another part of the brain - so, if it were true that thinking cause tumor growth, then it would depend where the tumor is located in your brain - thinking could actually cause tumor stasis (less growth). But of course, another problem in the study is that tumor growth is caused by many factors, such as factors related to the initial reason that a tumor started to grow, and other immunological and metabolic factors. Carcinogenics is complicated to say the least.

Finally, this is not a criticism of the researchers who intensively labor to find cause and cures for such horrible diseases like brain tumors. This is a critique and criticism, in my own style, of neuroscience news and spurious conclusions that are spread through the news and the web.

_______________________

Report on differences between mouse and human immunology:
http://www.jimmunol.org/content/172/5/2731.short

Original Article Here:
http://www.huffingtonpost.com/2015/04/27/thinking-fuels-brain-tumor-growth_n_7130838.html

* Carolyn Gregoire is a Senior Writer at the Huffington Post, where she reports on health and wellness, psychology and human behavior, and brain science

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