Dr. Lyman (The Painful Truth: The new science of why we hurt and how we can heal, 2022) cites extensive studies done by medical professionals and scientists to make the compelling, albeit not widely accepted, medical argument that brain, immune system and gut microbiome are the human body’s inter-connected “defense systems” against mental and physical diseases [pg. 183].
He believes that an imbalance in or damage to any one of these systems leads to chronic inflammation. This, he writes, is the root cause of various mental and physical ailments [185]. This evidence-based knowledge, he says, can help expand treatment options for various mental illnesses (depression, seizures and schizophrenia) [101, 113, 114, 137], autoimmune disorders (rheumatoid arthritis) [116, 128,129], neurodegenerative diseases (dementia, Alzheimer’s) [121, 172, 173, 175], atherosclerotic disease (heart attacks and strokes) metabolic disease (diabetes and obesity), and cancer [186-187].
He takes readers through the three meningeal lymphatic vessels (that exist between skull and brain, [23] which act as gatekeepers and “connect the borders of the brain to the rest of the body’s immune system”) [25], microglia (“brain’s resident immune cells”) [31], and vagus nerve (“a long nerve from brain stem that communicates with most of our internal organs, including the gut“) [34, 74].
Then he focusses on the gut which is the largest immune organ in the body and has its own (“enteric”) nervous system and is connected to the brain by four primary pathways: neural, endocrine, metabolic and immune [81]. He theorizes that a microbial imbalance in gut flora can lead to a dysfunctional prefrontal cortex (which is “implicated in most mental health conditions”) [76]. He believes that "mind is moulded and manipulated by the trillions of microbes that live within us." [69] An addiction to fast food, he suggests, may be due to abundance of fat-and-sugar-loving microbiome in gut [80]. Inflammation, caused by virus, bacteria, parasite or environmental factors, affects mood molecules (serotonin and dopamine) [121] and slows down neurogenesis of the hippocampus (part of brain that helps remember short-term and long-term memory, and has a key role in mood and emotion). This slowdown, in turn, leads to depression [121-122].
He encourages readers to look for the treatment of depression outside the brain and in the gut, lymph nodes, bone marrow or the spleen [113]. He mentions the case study of a woman who was diagnosed first with anxiety disorder, then epilepsy and ultimately schizophrenia, whose symptoms completely vanished after she received therapies of steroid, plasma exchange and IVIG (intravenous immunoglobulin). [101] In fact, he quotes trials that reveal people with high inflammation markers (C-Reactive Protein, cytokines such as IL-6) who do not respond well to traditional anti-depressants [118] and heal better with biologics (new lab-made protein, such as an antibody) [114]. In one such trial, a new antibody drug 'sirukumab' relieved rheumatoid arthritis by targeting cytokines for IL‐6, and 'ustekinumab' treated psoriasis by blocking the cytokines for IL‐12 and IL‐23. [128-129]
He encourages readers to be proactive and develop healthy lifestyle to reduce or eliminate inflammation in the body. These include diverse plant-based and fermented food diet, regular movement and exercise, good sleep cycle and mindfulness [190-234]. In fact, he proposes good dental care to reduce chance of dementia [174-175].
Since this is an emerging science, time and continued lab-based research, will confirm this book’s place in the field of integrated medicine as either controversial or revolutionary.
Memorable Quotes / Theories:
xvi: More and more people are experiencing – and more and more doctors are witnessing – conditions that cannot be neatly associated with specific organs, symptoms or specialties.
The reality is that there is no mental disorder that is not also physical, and most physical diseases have some mental element to them.
It is my contention that your mind and your immune system are not simply linked, but can be viewed as part of the same system: I will call this the ‘defence system’.
There had long been clues in Greek, Hebrew and early Islamic texts that humans could directly spread disease to each other, but even by Hooke’s time, ‘contagion theory’ had never really caught on. However, probably around the time Hooke identified the first cell, another revolution in the history of infection and immunity was taking place. This revolution did not emerge in a European metropolis, but instead a village in India or China that has long been lost to history. Someone had realized that smallpox could be prevented.
Variolation’s first scientific test came in 1721. Lady Mary Wortley Montagu, wife of the British ambassador to the Ottoman court in Constantinople, returned from the East as a fervent advocate of this mysterious treatment. In the Ottoman Empire, she spent extensive time with local women to explore and record their customs, and came upon the practice of variolation.
31:Microglia (your brain’s resident immune cells) are not just the brain’s equivalent of macrophages, they are the sculptors of our brains.
33: One brain‐immune connection has been termed the ‘inflammatory reflex’. Following the triggering of inflammation in the body, inflammatory cytokines are detected by the vagus nerve.
34: Today it is clear – and this is no overstatement – that the brain is an immunological organ. It has multiple lines of communication with the body’s immune army, has a powerful immune garrison in the skull and meninges, and even has its own specialized mercenary force of microglia. The brain and the immune system are tethered together by vessels (lymphatic and blood) and nerves. They speak the same language. You could even say that they are part of the same system. There is a part of us that feels this brain‐body link on a deep, instinctive level, but the human mind’s need for compartmentalization – which has influenced the development of separate scientific fields and the ordered progression of medical education – has blinded us.
56: Lisa Feldman Barrett is one of the main proponents of this theory. She describes emotion as ‘your brain’s creation of what your bodily sensations mean, in relation to what is going on around you in the world’. She argues that emotions are a ‘prescription for action’, specifically for behaviours that will keep our body in balance. Emotions are goal‐directed, the ultimate goal being the minimization of uncertainty and a balanced state of homeostasis in the body......Looking at the extremes, psychiatric diseases can be seen as disorders of inference. Over‐predicting and attributing excessive salience to sensory data results in hallucinations and delusions – the fantasies that our brains are constantly generating are not kept in check by the sensory evidence that should temper them. The opposite can result in dissociation – the experience of detachment from your emotions, your body or the world.
58: Our perceptions are a product of both the bottom‐up (sensations brought about by a bacteria or virus) and the top‐down (our brain’s predictions of the body and the world).
76: ...a 2016 study, was that microbe‐deficient mice have very strange prefrontal cortices....Such is its importance to the working of the mind – including decision‐making, planning, personality and behavioural control – that a dysfunctional prefrontal cortex is implicated in most mental health conditions.
79: The gut is our largest reservoir of microbes and it is our largest immune organ;
80: Different microbes have different tastes – Bacteroidetes love fat, Prevotella have a penchant for carbs and Bifidobacteria are addicted to fibre – so the makeup of our gut microbiome probably both reflects and influences our food choices. An addiction to fast food might partly be down to fat‐ and sugar‐loving microbes in your gut making persistent delivery requests. As behaviour – including willpower – is partly microbial, if you want to change your diet to improve your health, perhaps altering the microbial environment is better than simply relying on willpower.
81: There are four primary pathways between the gut microbiome and the brain: neural (relating to the nervous system), endocrine, metabolic and immune. Our gut is sometimes termed our ‘second brain’, as it has its own nervous system (the ‘enteric nervous system’) that contains more nerves than the human spinal cord. Its most well‐known role is unconsciously and rhythmically squeezing food down the pipe of the intestines, but – as we’ve seen – the gut is also directly linked to the brain via the vagus nerve. The vagus has long ‘feet’ that dig into the lining of the gut, and in 2015 it was discovered that these feet contain ‘neuropod cells’ that taste the environment of the gut and directly pass signals up to the brain.
98:In 2005 Dr Josep Dalmau, a Catalan neurologist working at the Uni‐ versity of Pennsylvania, had his curiosity piqued by some mysterious cases. He had identified four young women who, despite the attention of legions of medical specialists, had a seemingly undiagnosable disease.1 They all presented with a relatively rapid onset of similar symptoms: hallucinations, delusions, memory problems and seizures. ...They all appeared to have encephalitis: inflammation of the brain. This is most commonly caused by a viral or bacterial infection, but in these four cases multiple investigations found no infectious cause.
First, spinal taps did indeed reveal signs of inflammation in the cerebrospinal fluid. Second, all four patients happened to have benign, congenital tumours on their ovaries, called teratomas.
99: Dr Dalmau hypothesized that all four of these women must have had some brain tissue form within their teratomas, and that the immune system of each woman’s body had detected this alien growth. Antibodies were then produced against the tumour, sticking to the abnormal tissue and flagging it for destruction by immune cells. This is all well and good, but once these women’s immune systems had started to produce antibodies against brain tissue found in the tumours, these new antibodies also homed in on the same targets in their own brain.
After almost a year of trial‐and‐error tinkering in the lab, dropping samples of the women’s spinal fluid on to frozen sections of rat brain, he found that the antibodies bound to one specific receptor: the NMDA receptor.
Through what Dr Dalmau describes as ‘a product of serendipity and effort’, a new disease had been discovered: anti‐NMDA receptor encephalitis.
NMDA (N‐methyl‐D‐aspartate acid) receptors reside on the sur‐ face of synapses – the tiny gaps between nerve cells in the brain.They are found all over the brain, but in particularly high concentrations in the hippocampus (the seat of memory formation) and the frontal lobe (crucial for the development and regulation of personality, emotions and problem‐solving). NMDA receptors are activated by a molecule called glutamate, which is critical for our brain’s ability to change and adapt to the constant barrage of stimuli pouring in from the outside world. We’ve seen that the brain is a remarkable, predictive machine that is constantly refining its model of the outside world by comparing external stimuli to the brain’s internal predictions. This process is dependent on properly functioning NMDA.
101: Susannah was bounced between specialists, collecting a sticker book of misdiagnoses: bipolar disorder, schizo‐affective disorder, alcohol withdrawal and, to quote one neurologist, ‘partying too hard, not sleeping enough and working too hard’...... Dr Najjar suggested a ‘three‐pronged attack’. This began with steroids, a crude tool to reduce inflammation in the short term. She then underwent plasma exchange: a dialysis‐like procedure in which her rogue immune cells were washed out of her blood and replaced. Finally, she would come back to hospital on a monthly basis to have intravenous immunoglobulin (IVIG), an infusion of donor anti‐ bodies that ‘mop up’ autoreactive antibodies in the blood. Susannah made a full recovery.
113: If I asked you to name a body part, outside of the skull, that holds the key to the treatment of depression, what would you choose? Having read the book so far, perhaps you might have chosen the gut, or even an immune organ such as lymph nodes, bone marrow or the spleen. I came to this left‐field answer after speaking with Professor Iain McInnes, a Glasgow‐based world‐renowned rheumatologist.
114: A brand‐new class of drugs, called biologics, had recently entered the clinical world. A biologic is essentially a lab‐made protein, such as an antibody, that has been designed to target a very specific molecule in the body. Biologics represented a new generation of anti‐inflammatories: if aspirin and steroids are shotguns, biologics are laser‐guided rifles.
116: Perhaps, for some people at least, depression and arthritis both resulted from the same root cause: inflammation.
118: Around a quarter of people living with depression have mildly raised levels of a commonly measured inflammatory marker called C‐reactive protein (CRP) in their blood, suggestive of low‐level, chronic inflammation. Other inflammatory molecules are also raised in the blood of individuals with clinical depression, and a 2022 study found robust evidence for increased numbers of numerous types of immune cells in the blood of sufferers. This group of people – who are both depressed and have raised inflammatory markers – is a particularly curious one. They tend to respond particularly poorly to conventional antidepressant medications.8 It also appears that inflammation is more strongly associated with some depressive symptoms than others: alongside the core symptoms of persistent low mood and anhedonia, individuals with raised inflammatory markers in the blood tend to experience greater fatigue, an increased need for sleep and more changes in appetite compared to the uninflamed. Clinicians have long known about this group of symptoms, which has historically been termed ‘atypical depression’, but it is only recently that we have seen clear evidence that this condition may be caused by inflammation. Could roughly a quarter of people diagnosed with depression – which would account for around 70 million people worldwide – be living with a whole‐body inflammatory disorder?
118-119: We always need to be careful not to assume that correlation means causation
128-129: One study, carried out in 2020, was able to look at very detailed patient data from eighteen clinical trials and factored in patients’ physical improvements. These trials had used a range of new anti‐ inflammatory drugs designed to target the inflammation behind various autoimmune diseases. Two drugs in particular demonstrated an improvement in low mood, regardless of improvement in physical symptoms. These were both antibody drugs that specifically targeted pro‐inflammatory cytokines: sirukumab relieves rheumatoid arth‐ ritis by targeting IL‐6, and ustekinumab treats psoriasis by blocking the cytokines for IL‐12 and IL‐23. Here we have data to back up Iain McInnes’s observations in his arthritis clinic: anti‐inflammatory medication treating the psychological symptoms of depression, regardless of the state of physical symptoms. This doesn’t just help to strengthen an argument for inflammation causing some forms of depression; it offers hope of a treatment.
129-130: In the first few years of the 1990s, researchers at the University of Bristol recruited around 14,000 pregnant women into the Avon Longitudinal Study of Parents and Children (ALSPAC) study, and have since been monitoring them, their children and partners over the past three decades. Khandaker found that among this treasure trove of physical, mental and social data, ‘they had measured the inflammatory markers CRP and IL‐6 in around 5,000 children when they were aged nine. This meant that we could look at these children when they were eighteen and see if inflammation in child‐ hood predicted depression later on. And indeed it did: kids with higher inflammatory markers in their blood aged nine were more likely to have depression when they were eighteen.’ This was still the case when Khandaker’s team statistically removed the effects of potential confounding factors such as sex, age, ethnicity, body mass index, past psychological problems and social class.
133: In 2020, researchers at the University of Cambridge, alongside a consortium of experts from across the United Kingdom, published some exciting findings. They analysed a range of immune cells taken from blood samples from around two hundred patients with depression and three hundred healthy controls. Individuals with depression generally tended to have considerably more peripheral inflammation than healthy controls, but researchers were also able to clearly identify a specific ‘inflamed depression’ subgroup, comprising around a third of those with depression.30 Alongside raised CRP and inflammatory cytokines – something already well established from other studies – they also found raised numbers of both innate and adaptive immune cells circulating in the blood of these patients. This subgroup also had more severe depression than others, reflecting other findings showing that those with inflamed depression tend to be those who don’t respond to conventional antidepressants. Perhaps we are not too far away from a future in which you present to your GP with symptoms of depression, are given a quick blood test and – if you’re identified as having inflamed depression – are offered a cure.
174: There is plenty of evidence to suggest a correlation between dementias such as Alzheimer’s disease and excessive, long‐term inflammation in the body, known as chronic inflammation. A 2010 meta‐analysis (an analysis of multiple papers, combining their findings) of 1,500 individuals found that those with Alzheimer’s disease tended to have raised levels of inflammatory cytokines in their blood...We also know that suffering from multiple infections increases the risk of developing dementia....An intriguing study, published by researchers at Stanford University in 2023, points the finger at one specific infectious agent: the varicella‐zoster virus.
174-175: A remarkable link between systemic inflammation and dementia was uncovered in 2016, when researchers at the University of Southampton found that those with gum inflammation (periodontitis) had a six‐fold increased risk of developing Alzheimer’s disease over a six‐month period.
183-234: [tips on food, exercise, mindfulness]