Dr Caroline Leaf – Serious questions, few answers (Part 1)

Caroline Leaf. The name is popping up more and more around Christian circles. I was curious to hear her speak, since as a Christian and a (family) physician, I like to know how people integrate science and spirituality. So I took the opportunity to drive down to Kings Christian Church on the Gold Coast to hear what she had to say.

I left with more questions than answers.  And some serious concerns.

The following blog posts are a discussion on some of the points that she raised. I simply don’t have the time to go through all of them, although I’m seriously considering whether to do a formal review and response to her teaching.

I had to divide up the original post into three parts to make it more manageable. Here’s part 1, in which I review her academic qualifications, her link of thoughts and illness, our innate wiring, and the myth of the mini-brain.

Part 2 of this post will look further at the pecking order of the mind and brain, some miscellaneous issues, and her ‘professional’ opinion on ADHD.

Part 3 will examine her claim that “Toxic thoughts are sin” and why such a statement is incongruent with the Christian faith.


For a start, she was introduced as a cognitive neuroscientist. Her CV lists her degrees as a Bachelor of Science, Masters in Speech Therapy and Audiology, and a PhD in Communication Pathology. She did not advise where she has tenure or does her research. Her CV lists guest lectures at a few Universities (Wits, University of Pretoria, University of Cape Town, University of Western Cape Annual Education Conference, SASHLA, Rotary Foundation), but no tenure.

Admittedly, the definition of a cognitive neuroscientist is somewhat vague (http://careersinpsychology.org/becoming-a-cognitive-neuroscientist/) but the term ‘cognitive neuroscientist’ confers the idea that one is actively involved in cognitive neuroscientific research, or at least in the recent past.

So the question remains: is she really a cognitive neuroscientist, or is she just a woman with a PhD that reads a lot?


The next thing to grab my attention was her statement: “75 to 98% of ALL illness is related to our thought life.” Somehow I doubt that. The influence of stress is high.  But I am a GP – I see sick people everyday, on the coal face, before they are collected in subspecialist clinics, or improve spontaneously. It’s a real stretch to ascribe stress to more than 30%. Looking at her book ‘Who Switched Off My Brain’ (Leaf 2009, p15), she says that 80% of all diseases are the result of our thought lives. So her own figures are conflicting. (The other thing is that, for a PhD recipient, she has poorly referenced her book!)

Besides, stress causes illness, but I’m not yet satisfied she’s proven that ‘negative’ thought and stress are the same thing.


She also claimed that the brain and the heart connect to every cell in your body. Again, it’s a bit of a stretch. Every cell needs to be bathed in nutrients from the blood which in turn is connected to the heart, and nerves are every where.  But there are many cells that are not innervated directly.

The only way that the brain or the heart are connected to every cell is simply because, technically, every cell is connected to every other cell. Like if everyone in a church stood up and held hands, the man in the front row would be “connected” to the woman in the back.

But she went further on her theory, by claiming that the heart has a mini-brain that directly influences the real brain – by making moral decisions on its own, and that it is part of our conscience. She justified her statement by saying that the heart has 40,000 interconnected nerve cells, and the heart is directly connected to the brain. But on that same logic, my rectum could be a mini-brain and be part of my conscience.

She alluded to the effect of ANF, atrial natriuretic factor. There are actually three natriuretic peptides. ANF, produced by the top two chambers of the heart, actually regulates blood pressure (http://www.cvphysiology.com/Blood%20Pressure/BP017.htm). If it has an effect on thought, it is secondary, not primary.


She also states that we are wired for optimism, and that emotions like fear are learned. That doesn’t make sense since I have seen research that shows a newborn baby is wired for pleasure and emotions like disgust. These pathways are developed and refined during childhood, but we are born with built-in templates for basic emotion.

I will have more in the next 24 hours, including her statement on the pecking order of the mind and brain, some miscellaneous issues, and her ‘professional’ opinion on ADHD.


Leaf, C. (2009). Who Switched Off My Brain? Controlling toxic thoughts and emotions. Southlake, TX, USA, Inprov, Ltd.