About a week ago I read a story about a recent study on a link between certain types of well-being the expression of certain genes. It sparked my imagination— that my thoughts could alter the expression of my genes. I thought about the study all week. It was so tantalizing I had to write a story on it. I lost the original link, but I Googled and found several write-ups of the same story.
The new study (Barbara L. Fredrickson, et. al, 2013)1 examines correlations between gene expression and different types of well-being.
We all know the difference between correlation and causation— there’s a strong correlation between the size of a fire and the number of firemen at the fire, but firemen don’t cause fires. So, for the Fredrickson study, to claim that your psychology influences gene expression, or that genes respond to how you conduct your life would be causation. You feel x, as a result your genes express y.
I wanted my story to emphasize personal choice. Select your thoughts to select your genes! Science finally proves what metaphysicists have known all along! But as I went back over the stories, I could not find any details on such a causal link. It looked like the study found a correlation only, not causation. Did I get the wrong takeaway about this story? I returned again to online write ups.
Gretchen Reynolds, in her Aug. 23, 2013 New York Times article “concluded” (her word), “[our minds] can, it seems, reward us with healthy gene activity when we’re unselfish — and chastise us, at a microscopic level, when we put our own needs and desires first.” That sure sounds like a causal link— your mental state rewards you with healthy gene activity. She ended her article with, “It may even be that this will enable your genes to respond more favorably to how you’re conducting your life.” There is a one word caveat in there: “may”. Odd word choice, since she started her article with “concluded”. So which is it, a conclusion or merely a possibility? Correlation or causation? The article never mentions either word, which seems to me like a substantial omission. Are you confused yet? I am.
Gretchen is not alone in sowing confusion. Science Daily’s July 29 headline read, “Be Happy: Your Genes May Thank You for It”, and their opening sentence read “A good state of mind — that is, your happiness — affects your genes, scientists say.” Again, that seems a pretty solid statement of causality. As with The New York Times, this article makes zero mention of either “correlation” or “causation”.
Read Science News’ headline— “Positive Psychology Influences Gene Expression in Humans, Scientists Say”2 — and their subhead, “According to a team of scientists from the University of North Carolina and the University of California, Los Angeles, different types of happiness have surprisingly different effects on the human genome.” Again, it sure sounds like a causal link. Again, “correlation” and “causation” are absent.
So journalists on three seemingly reputable sites strongly suggest a causal link. So perhaps I was the one who was mistaken; it wouldn’t be the first time I misread something. So I emailed senior study author Prof Steven Cole and just asked him if this study found a causal link. His reply: “Our study was correlational and cannot formally establish a causal effect of eudaimonic or hedonic well-being on gene expression. We note that pretty clearly in the paper.”
So I read the paper. Sure enough, it says:
“The present findings are limited in several respects. These results come from a cross-sectional analysis, and the observed associations may reflect a causal effect of immune biology on affect or social behavior…. direct experimental manipulations of hedonic and eudaimonic well-being will be required to clearly define their causal effects”
That’s a pretty clear statement of correlation and not causation. So what’s going on here? How is it that so many (I assume) decent news sites misrepresented this story?
Many of us want it to be true that we can wield power over our genes with our thoughts. It’s not like this notion is generally without precedence3,4,5,6,7,8,9,10,11, it’s just that it’s not a conclusion that can be drawn from this particular study. The angle of these write-ups has a moralistic appeal that aligns with every major religion: good-deeds will be rewarded, hedonists will be punished… genetically. Morality codified at the genetic level. This angle becomes so compelling that the study is widely reported as just that— great story… let’s not let facts get in the way. There may indeed be a causal link between hedonic (feeling good) and eudaimonic (doing good) well-being and the expression of certain genes, but this study didn’t look for that causal link and so it didn’t find it.
Ok, so at this point we can all agree that this study found no causal link. But what about correlation, it found at least that, right? Well, gentle reader, it seems any easy conclusions around this story lie teasingly outside of our grasp. Just when I thought I could put this matter to bed, my brother sent me yet another pertinent link. James Coyne over at PLOS Blogs also casts a critical eye, but not on the reporting; he is critical of the study itself. He characterizes the report as containing “unnecessarily ponderous sentences” and claims it contains “fatal flaws”. While Coyne claims error, he fails to posit what could have resulted in such a low P value other than different types of well-being. Fredrickson et. al found something. If not correlation, then what? Coyne doesn’t say… so I’m inclined towards the validity of their results.
What is the takeaway here? Well, for one, being informed is exhausting. Certainty seems an indulgence of the naïve and the arrogant. But perhaps I can cast one certain statement your way: don’t believe everything you read.
- Barbara L. Fredrickson, Karen M. Grewen, Kimberly A. Coffey, Sara B. Algoe, Ann M. Firestine, Jesusa M. G. Arevalo, Jeffrey Ma, and Steven W. Cole. A functional genomic perspective on human well-being. PNAS, July 29, 2013 DOI: 10.1073/pnas.1305419110 [↩]
- Positive Psychology Influences Gene Expression in Humans, Scientists Say, Aug. 12, 2013 [↩]
- There is a precedence for a causal link between certain emotions and gene expression, as noted by this study, “previous studies have found that circulating immune cells show a systematic shift in basal gene expression profiles during extended periods of stress, threat, or uncertainty”. [↩]
- Cole SW, Conti G, Arevalo JM, Ruggiero AM, Heckman JJ, Suomi SJ. Transcriptional modulation of the developing immune system by early life social adversity. Proc Natl Acad Sci U S A. 2012 Dec 11;109(50):20578-83. doi: 10.1073/pnas.1218253109. Epub 2012 Nov 26. PubMed PMID: 23184974; PubMed Central, PMCID: PMC3528538. [↩]
- Tung J, Barreiro LB, Johnson ZP, Hansen KD, Michopoulos V, Toufexis D, Michelini K, Wilson ME, Gilad Y. Social environment is associated with gene regulatory variation in the rhesus macaque immune system. Proc Natl Acad Sci U S A. 2012 Apr 24;109(17):6490-5. doi: 10.1073/pnas.1202734109. Epub 2012 Apr 9. PubMed PMID: 22493251; PubMed Central PMCID: PMC3340061. [↩]
- Powell ND, Sloan EK, Bailey MT, Arevalo JM, Miller GE, Chen E, Kobor MS, Reader BF, Sheridan JF, Cole SW. Social stress up-regulates inflammatory gene expression in the leukocyte transcriptome via β-adrenergic induction of myelopoiesis. Proc Natl Acad Sci U S A. 2013 Sep 23. [Epub ahead of print] PubMed PMID: 24062448. [↩]
- Antoni MH, Lutgendorf SK, Blomberg B, Carver CS, Lechner S, Diaz A, Stagl J, Arevalo JM, Cole SW. Cognitive-behavioral stress management reverses anxiety-related leukocyte transcriptional dynamics. Biol Psychiatry. 2012 Feb 15;71(4):366-72. doi: 10.1016/j.biopsych.2011.10.007. Epub 2011 Nov 16. PubMed PMID: 22088795; PubMed Central PMCID: PMC3264698. [↩]
- Creswell JD, Irwin MR, Burklund LJ, Lieberman MD, Arevalo JM, Ma J, Breen EC, Cole SW. Mindfulness-Based Stress Reduction training reduces loneliness and pro-inflammatory gene expression in older adults: a small randomized controlled trial. Brain Behav Immun. 2012 Oct;26(7):1095-101. doi: 10.1016/j.bbi.2012.07.006. Epub 2012 Jul 20. PubMed PMID: 22820409; PubMed Central PMCID: PMC3635809. [↩]
- Black DS, Cole SW, Irwin MR, Breen E, St Cyr NM, Nazarian N, Khalsa DS, Lavretsky H. Yogic meditation reverses NF-κB and IRF-related transcriptome dynamics in leukocytes of family dementia caregivers in a randomized controlled trial. Psychoneuroendocrinology. 2013 Mar;38(3):348-55. doi: 10.1016/j.psyneuen.2012.06.011. Epub 2012 Jul 15. PubMed PMID: 22795617; PubMed Central PMCID: PMC3494746. [↩]
- Bhasin MK, Dusek JA, Chang BH, Joseph MG, Denninger JW, Fricchione GL, Benson H, Libermann TA. Relaxation response induces temporal transcriptome changes in energy metabolism, insulin secretion and inflammatory pathways. PLoS One. 2013 May 1;8(5):e62817. doi: 10.1371/journal.pone.0062817. Print 2013. PubMed PMID: 23650531; PubMed Central PMCID: PMC3641112. [↩]
- Qu S, Olafsrud SM, Meza-Zepeda LA, Saatcioglu F. Rapid gene expression changes in peripheral blood lymphocytes upon practice of a comprehensive yoga program. PLoS One. 2013 Apr 17;8(4):e61910. doi: 10.1371/journal.pone.0061910. Print 2013. PubMed PMID: 23613970; PubMed Central PMCID: PMC3629142. [↩]