CHAPTER 8 - “Toxic” Thoughts
Toxins! They’re everywhere!
The notion of “toxins” has been increasing for a while, in part because of the power of mass marketing and the celebrity effect. It didn’t take a lot of research to find a myriad of health websites warning of the dangers of hidden harmful substances everywhere: your soup bowl, your sofa, your shower curtain, cookware. Apparently light is even a toxin! 
Yet if you ask someone what toxins are, no one can really tell you. “They’re there in our food, and our air, and … ah … and they must be bad, because … well … they’re toxins.” So “toxins” has become a catch-all description of those things inside us that are somehow bad, even if no one knows what they are or what they do to us. And because they are so nebulous, they get blamed for every symptom we can’t otherwise put our finger on.
Of course, if there are “toxins” in our bodies, then we must need products to help us rid our bodies from them. Never mind that our liver and kidney’s already detoxify the substances we consume, and there’s no scientific proof to support detoxing . Never let the truth get in the way of good marketing.
One of Dr Leaf’s central arguments is that thought can be toxic. She said, “Toxic thoughts are thoughts that trigger negative and anxious emotions, which produce biochemicals that cause the body stress.” [1: p19] In order for something to be toxic, it has to be poisonous. “Poisonous” implies that something is capable of producing death or illness if taken into the body.
Are our thoughts capable of producing death or illness?
In this chapter, I want to discuss Dr Leaf’s core argument in more detail, review the statements she makes about toxic thoughts, and discuss why the popular notion of toxins, and Dr Leaf’s notion of toxic thoughts, are both unscientific.
“Negative” thoughts are a symptom not a cause
Remember the last time you had a cold? Was your sore throat or runny nose the cause of the cold, or just symptoms? Clearly, the runny nose and sore throat are just symptoms – sensations of the illness that you are aware of. The actual cause is usually a virus, which you wouldn’t be able to detect unless you had a spare electron microscope laying around.
Thought is a projection of information from the deeper systems in the brain, specifically designed to process the data more efficiently. As shown by the CAP model, there are many different components that feed up into thought. Thought doesn’t drive our brain - our brain drives our thoughts. Since the brain drives our thoughts, our thoughts cannot do anything that the brain has not allowed. If our thoughts aren’t right, it’s the brain that is the underlying issue.
For example, anxiety and other mood disorders may result in unwelcome, unpleasant thoughts. But they occur because of a strong genetic pre-disposition that has been primed, resulting in a much stronger physiological response, and often coupled with personality vulnerabilities and abnormalities of perception. Abnormal thoughts are the result of these factors, not the cause of them.
Consider it from a different angle. If thoughts were truly the source of our mental health problems, then purely cognitive therapies would have a much greater impact on the treatment of these disorders than either medications or purely behavioural therapies. But as we’ve discussed in chapter 7, when cognitive therapies are added to behavioural therapies, there is no incremental benefit , and pharmaceuticals are as beneficial as cognitive therapies in most mental health disorders .
In research work that has intentionally studied thought separately to stress, thought has not been associated with any significant changes in stress or health behaviour. A study of college students in the US showed no correlation between “negative” thoughts, life stress and health behaviour . It has also been confirmed that thought alone does not lead to detrimental biological changes, such as significant changes in immune function .
So thought does not significantly contribute to our mental or physical health. Rather, dysphoric thoughts are the eventual outcome of any number of dysfunctional inputs or process steps in the neuropsychological chain, just as a sore throat is a symptom of an underlying viral infection, not the cause of it.
Why “toxic thoughts” are unscientific
So considering thought in its appropriate context already shows that the idea of “toxic” thoughts is incompatible with modern science. In order to bolster the concept of “toxic” thoughts, Dr Leaf has to reinterpret or ignore various psychological, neuroscientific, and theological facts. When reexamined, these facts confirm that “toxic” thoughts are unscientific and unscriptural.
“Toxic” thoughts are actually beneficial
According to Dr Leaf’s definition, “Toxic thoughts are thoughts that trigger negative and anxious emotions, which produce biochemicals that cause the body stress.” [1: p19] In other words, thoughts that cause stress, as well as anxiety and other “negative” emotions, are always detrimental.
In chapter 4, we discussed the stress-productivity curve and the Yerkes-Dodson Law. According to these two pillars of psychological science, there is a power band in which we work our best when we are under a balanced influence of stress. This is where we all are during the course of our usual daily lives. Stress is generally adaptive - it confers a survival advantage. Why else would God have given it to us in the first place?
A stress response can be seen in people who are mentally preparing for any significant mental or physical task. A recent study suggests that release of cortisol (a stress hormone) in moderate amounts actually improves memory recall . “Anxious emotions”, such as fear, or “negative” emotions, such as anger, also provide a survival advantage. Without appropriate fear, we would not recognize danger signals. Without anger, we would not have the motivation to overcome some obstacles or communicate that intention.
As Skinner and Zimmer-Gembeck observe, “adaptive coping does not rely exclusively on positive emotions nor on constant dampening of an emotional reaction … Adaptive coping profits from flexible access to a range of genuine emotions as well as the ongoing cooperation of emotions with other components of the action system.” 
So, if Dr Leafs definition is correct, then adaptive survival responses are “toxic”. Common sense tells us that this is not true.
“Causes of stress”
Hans Selye said about stress, “Everybody knows what stress is, but no one really knows.”  That’s because everyone suffers from stress at some point, but the causes of stress are as unique as each individual that is affected by it.
What’s clear is that thought does not cause stress, but is a symptom. “Stressed” thoughts may appear as a result of being stressed, but they are not the cause of the stress, any more than a sore throat is the cause of a viral infection.
Science shows that stress generation is predominantly genetic. Some independent sources of stress affect everyone at some stage (bereavement, natural disasters, job losses, relationship break downs). But the people that are affected the most by stress not only handle all stress poorly because of genetic changes (5-HTTLPR gene polymorphisms) [10, 167], but are also genetically wired to significantly contribute to their own stress. These unintentional, self-generated episodes of stress are called dependent stressful life events (dSLE’s for short). Studies confirm that dSLE’s are strongly genetically influenced [120, 168]. It’s true that cognitive styles (how we process information that we receive from our environment) are influential in the development of stress. Studies link the “negative inferential styles” form of cognitive processing to levels of stress. But again, genetics play a strong role in our personality and resilience [120, 123, 127].
“The high road and the low road”
Anxious and negative emotions aren’t driven by thought, let alone “toxic” thought.
According to the Dual Processing model, the brain has two pathways that it processes information via. The first path involves the incoming signals passing into the thalamus deep in the brain, which provides a rough analysis as to what the stimulus might be, while the amygdala codes whether it is dangerous or pleasant. The thalamus acts on this rough, rapid analysis to form a rough, rapid action response. In the case of fear, it primes or drives our system to “flight/fight or freeze”.
The second pathway involves the signal moving up through to the cerebral cortex where the executive parts of our brain have a chance to process the information in a finer, more detailed way, sometimes using conscious broadcast.
Our feelings often act without our awareness or control. Anger often seems to bubble up from the internal depths of our limbic system, and in someone who is already primed, it doesn’t take much for the primeval anger to explode. Then the cerebral cortex has to try and catch up. Fear is the same. I’m not a fan of practical jokes, but I have seen enough TV footage of people being punk’d to know that if you brush an unsuspecting victim’s shoulder with something resembling a tarantula, they don’t relax! They jump, scream, punch, scratch or run first, and only stop a couple of seconds later when their cerebral cortex catches up.
I have a personal rule for my practice: never have friends as patients or patients as friends. I made this rule after some friends bought their one-year-old daughter in to see me for her vaccinations. I did the usual doctor things and gave her the needles, and as expected she was pretty cranky. One week later the same friends invited me to the same child’s one-year birthday party. From thirty meters away, the child saw me and screamed, and hid behind her mother. Now, one year olds don't have thoughts in the same way we do. Their frontal lobe is still only beginning its development and they are still more reflexive than cognitive. The fact that she screamed and hid in fear had nothing to do with cognitive thought, and all to do with pure limbic associative learning! Fear is not thought driven.
Another observation that supports that stress is not thought-driven is white coat hypertension. Most patients walk into my office perfectly calm. For some people, when they test their blood pressure at home in their lounge chair, it's fine. But then when I test it, it’s sky high. If thought was required to trigger a stress response then these people should have a normal blood pressure, since they are not thinking negative or toxic thoughts. They are sitting in the chair in front of me, relaxed. I'm not so scary that they become fearful of me. When I ask them how they’re feeling, they say they don’t feel stressed in any way. So their stress response is independent of their conscious thought. The situational trigger of being near a doctor has, via the "low road", primed them for fight or flight, independently of the "high road" of the conscious processing from their cerebral cortex.
So the Dual Systems model and the Cognitive-Action Pathways model demonstrate that there are two separate pathways for information processing, evident in fear responses, anger responses, and in medical conditions such as white coat hypertension. The low road bypasses the cerebral cortex entirely, so anxiety, stress and anger responses cannot be solely generated by thoughts as Dr Leaf suggested.
The Mind-Brain Link
In chapter 1 of her new book, Dr Leaf states that, “Our mind is designed to control the body, of which the brain is a part, not the other way around.” [2: p33] Her statement is in conflict with basic medical science.
The brain controls the mind because drugs, and metabolic disorders that all act on the brain have been proven to change peoples thought patterns. For example, medications for mood disorders act on the neurotransmitter levels within the brain, and on synaptic growth factors . Yet they have been shown over and over again to improve mood and the pattern of thoughts that brains generate [169-171]. Similarly, recent research to show that medications have been shown to improve the extinction of fear in anxiety disorders such as panic disorder, OCD, Social Anxiety Disorder, and PTSD .
Injuries or lesions to the brain can also cause changes to the mood, personality or thought pattern of the afflicted patients. One of the most famous examples was the case of Phineas Gage, who accidentally blasted a foot-long steel rod through his skull in 1848, severely damaging the left frontal lobe of his brain. History records that his personality changed from polite, well mannered, and well spoken to fitful, irreverent, impatient of restraint or advice, obstinate and capricious . Injuries and lesions of the parietal lobe of the brain changes the way people see their own bodies. Baars writes, “Patients suffering from right parietal neglect can have disturbing alien experiences of their own bodies, especially of the left arm and leg. Such patients sometimes believe that their left leg belongs to someone else (often a relative), and can desperately try to throw it out of bed. Thus, parietal regions seem to shape contextually both the experience of the visual world and of one’s own body.” 
Surgery to the frontal lobe had the same result on mood and cognition. Fumagalli and Priori note that “in 1942 Walter Freeman reported the results for 200 lobotomy cases and acknowledged that the procedure was not always benign: 14% of the patients who underwent prefrontal lobectomy subsequently manifested seizures and impaired cognition, affect, mood and social behaviour.” 
So medical science clearly shows that the brain drives thoughts, and Dr Leaf’s suggestion that the mind controls the brain is not supported by basic neurobiology.
Choice and free will
In chapter 2 of her 2013 work, Dr Leaf argues that every choice we make is completely under our conscious control, and that “our free will influences our thinking which determines our state of mind.” [2: p41]
This is in direct disagreement with cognitive neuroscience. As Leisman notes, “Surprisingly, recent research suggests that conscious choice plays a smaller role in our actions than most people assume. In particular, it (conscious choice) often comes after brain activity that initiates bodily movements, and many researchers conclude that the conscious choice does not cause the movement.”  Ellerton, a lecturer in Critical Thinking at the University of Queensland, noted in a piece for the academic blog, The Conversation, “We like to think that we reach conclusions by reviewing facts, weighing evidence and analysing arguments. But this is not how humans usually operate, particularly when decisions are important or need to be made quickly. What we usually do is arrive at a conclusion independently of conscious reasoning and then, and only if required, search for reasons as to why we might be right.” 
The Oracle explained it to Neo, “… you didn't come here to make the choice. You've already made it. You're here to try to understand why you made it.” (Matrix Reloaded, 2003)
Ironically, most of Dr Leaf’s background explanation of her statement is fairly accurate – she discusses the implicit processes of the brain before the broadcast of thought into consciousness, and the human capacity of “awareness of awareness”, that we can observe our own thought. She calls this the “Multiple-Perspective Advantage”, although it’s just the long-recognised principle of metacognition, regifted.
Her statement that “free will” strongly influences us is incorrect, because she does not consider specific neurological conditions defined by movements that are involuntary, and she mislabels any neurological activity as thought.
Medical science has documented a number of disorders demonstrating complex motor patterns and speech occurring without the brains conscious awareness. The Alien Hand Syndrome is a syndrome in which certain lesions in the brain cause one of the patients hands to perform actions separate to the patients wishes . Wegner describes two such patients, a lady whose “left hand would tenaciously grope for and grasp any nearby object, pick and pull at her clothes, and even grasp her throat during sleep … She slept with the arm tied to prevent nocturnal misbehavior”, and a man who, “While playing checkers on one occasion, the left hand made a move he did not wish to make, and he corrected the move with the right hand; however, the left hand, to the patient’s frustration, repeated the false move. On other occasions, he turned the pages of the book with one hand while the other tried to close it; he shaved with the right hand while the left one unzipped his jacket”.  The patient does not consciously will the “alien hand” to move, in fact, the “alien hand” often acts against the person’s will, but they’re meaningful actions, not random movements. Similarly, Tourette’s syndrome involves involuntary motor movements, vocalisations and sometimes speech . As we discussed earlier, parasomnias can be quite complex behaviours, all occurring during sleep, without conscious control .
There’s obviously a separate system that acts outside of our conscious will. If it’s true that not all sensory input leads to conscious awareness, then it’s equally true that there are actions that do not engage our conscious awareness, and the Alien Hand Syndrome suggests an entirely plausible mechanism.
Her other error comes in her definition of thought. She defines all brain activity as thoughts, including all unconscious brain activity. Her assumption is that all of the implicit, uncontrolled, unconscious brain activity leading to our current choice is the result of all the previous choices over time that we did have control over. “As you think, you are making your way to a decision of some kind, whether it’s as simple as what to eat or as complex as choosing one of several different courses of action you face.” [2: p46]
However, the implicit neurological activity that preceded an action is not just defined by our past choices, but by many other things beyond our control – our environment, our genes, and our reinterpretation of our memories, which as we have discussed, is not a precise recall of our past but an imprecise blend of our overall experience.
Further, we know that thought is dependent on implicit activity of our brains. If I ask you what is 2 x 2, the answer will invariably pop into your head without any thought as to how the answer was formed. Decision-making is the same. Even before an action is taken, the brain has already reviewed a number of possible scenarios and through a competitive process, created a short list based on needs and pre-emptive rewards, and usually primed our brains motor areas in readiness for the final action to be taken. So our unconscious neurological activity has already limited the choices we find projected into our consciousness.
If all choices are preceded by implicit neurological activity that we can’t control, then that choice isn’t truly free. How then can we have “free will”? Wegner noted the same, “If we put in a module (in a hypothetical artificial brain) that creates actions out of any sort of past experiences or memories, that fashions choices from habits or attitudes or inherited tendencies, we do not get freedom, we get determinism.” 
At best, we have constrained freedom of choice – choices limited by the bounds of our consciousness and the components of it. This is exactly what experts in this field, such as Wegner  and Bonn  propose, and what I have discussed in relation to the Cognitive-Action Pathways model.
Dr Leaf writes that the thinking we do causes biological changes in our brains. I’m not sure how valid her list is on the top of page 47 , but even if it’s water tight, the same biological changes occur with any neurological activity, whether intentional or not. Seizures, for example, cause widespread electro-chemical and magnetic changes, but they’re not a form of thinking, and they are certainly not under our direct control. The brain of a foetus does not have the capacity for conscious thought in the same way that adults do, but the foetal brain is undergoing some of the most rapid neurological activity and growth that a person will ever have. Thus, it’s incorrect to claim that choice and free will is the sole cause of physical and chemical changes to our brain.
She then suggests that our choices are the key initiator of the gene switches that wire our thoughts into our brains, because our choices influence epigenetics, which then starts the process of gene expression. We’ll discuss this more in chapter 12, but suffice to say, epigenetics has only a small role in gene expression, and thought has nothing to do with epigenetics. The vast majority of gene switches are switched on by other genes, or by proteins that have been made directly by the genes, in order to switch on other genes. Epigenetics has very little to do with it and there’s no direct evidence that thought influences epigenetics anyway.
Dr Leaf claims that the CREB gene is switched on directly by thought, which then causes the cell to grow healthy branches. But CREB is a gene switch involved in many cells (not just nerve cells), and in many different animal species, including the sea slug, Aplysia . Thus, thought cannot be the switch that triggers CREB expression, unless she’s suggesting that sea slugs have thought. CREB is important to the formation of long-term memory . But again, thought and memory are not the same thing. So it’s incorrect to claim that thought causes the activation of the CREB gene.
Did Jesus have “toxic thoughts and emotions”?
In the Garden of Gethsemane, the gospels record that Jesus, the spotless lamb of God, about to be crucified for the sins of all mankind, was “overwhelmed with sorrow to the point of death” (Mark 14:34, Matthew 26:38), and became so distressed by the ordeal he was about to endure that he literally sweat drops of blood (Luke 22:44). Where do you think Jesus was on the stress spectrum according to those accounts? I’d wager that it wasn’t “healthy stress”.
Rev Bob Deffinbaugh wrote that, “Jesus spent what appears to be at least three agonizing hours in prayer.” He also noted that, “Never before have we seen Jesus so emotionally distraught. He has faced a raging storm on the Sea of Galilee, totally composed and unruffled. He has faced demonic opposition, satanic temptation, and the grilling of Jerusalem’s religious leaders, with total composure. But here in the Garden, the disciples must have been greatly distressed by what (little) they saw. Here, Jesus cast Himself to the ground, agonizing in prayer.” 
There is no other way to explain it - Jesus suffered severe and prolonged mental anguish to the point that it had physical effects. By Dr Leaf’s definition [1: p19], Jesus had “toxic” thoughts.
Dr Leaf also states, “hostility and rage are at the top of the list of toxic emotions” [1: p30], and that “Stress is the direct result of toxic thinking.” [1: p29] But again, scripture documents Jesus displaying emotions and actions that Dr Leaf defines as “toxic”.
In John 2:13-17, it says, “When it was almost time for the Jewish Passover, Jesus went up to Jerusalem. In the temple courts he found people selling cattle, sheep and doves, and others sitting at tables exchanging money. So he made a whip out of cords, and drove all from the temple courts, both sheep and cattle; he scattered the coins of the moneychangers and overturned their tables. To those who sold doves he said, ‘Get these out of here! Stop turning my Father’s house into a market!’ His disciples remembered that it is written: ‘Zeal for your house will consume me.’”
So Jesus saw the sellers and the money exchangers, then in a pre-meditated way, took small cords and fashioned a whip out of them, and proceeded to use that whip to violently and aggressively overturn the tables of the merchants and spill the money of the money changers. John adds a post-script - “Zeal for your house will consume me.” So Jesus wasn’t prancing around for show. He was consumed with a deep, passionate anger.
Indeed, God himself displays anger. There are a number of times in the Old Testament where the wrath of God was kindled, either towards Israel or their enemies. For example, 2 Kings 23:25-27 says, “Notwithstanding the Lord turned not from the fierceness of his great wrath, wherewith his anger was kindled against Judah, because of all the provocations that Manasseh had provoked him withal.” Numbers 11:33 and Deuteronomy 11:16-17 are other examples, and an extensive study on the wrath of God would reveal many more.
In the creation account in Genesis 1 and 2, the scripture describes that God made man in his image. If God has emotions such as anger, and he made us in his image, then we have also been made to experience emotions such as anger.
If God has anger and we are made in his image, then he gave us the capacity for anger. If God gave us the capacity for anger, then anger itself isn’t toxic, and neither is it necessarily sinful or impure, since Jesus also displayed anger. Therefore anger, like the other emotions, is neutral. Anger can be used in both maladaptive ways, and in adaptive ways, and likewise, “positive emotions” can be used for maladaptive purposes as well as adaptive purposes. It’s ultimately the use of the emotion rather than the emotion itself that’s the issue. Thus, Dr Leaf’s statement that anger is negative and “toxic” is overly simplistic and ultimately false.
Are thoughts toxic?
In summary, thoughts by themselves don’t have any effect on the brain, because the brain is the driver of thoughts rather than thoughts being the driver of our brains. Studies show that there is no link between “negative” thinking, stress and health behaviours, and psychological therapies such as ACT prove that meaningful improvement can be made in psychological issues by changing behaviour, irrespective of thought. “Negative” thoughts are symptoms of underlying disturbances, not the causes of them.
Dr Leaf makes a number of claims to try and justify her theory of toxic thoughts, but the weight of established scientific evidence of the relationship of the mind and brain, the role of genes like CREB, and the nature of choice and free will, is against her.
Just as there’s no scientific evidence for toxins in our body, there’s also no scientific support for toxins in our thoughts either.