I t seemed a bit of a joke at the time – that I should have my own brain scanned. I should have known better. I had always advised patients and friends to avoid having brain scans unless they had significant problems. You might not like what you see, I told them. I had volunteered to take part in a study of brain scans in healthy people. I was curious to see my own brain, if only in the greyscale pixels of an MRI scan. I had spent much of my life looking at brain scans or living brains when operating, but the awe I felt as a medical student when seeing brain surgery for the first time had fallen away quite quickly once I started training as a neurosurgeon. Besides, when you are operating you do not want to distract yourself with philosophical thoughts about the profound mystery of how the physical matter of our brains generates thought and feeling, and the puzzle of how this is both conscious and unconscious. Nor do you want to be distracted by thinking about the family of the patient under your knife, waiting, desperate with anxiety, somewhere in the world outside the theatre. You need to separate yourself from these thoughts and feelings, although they are never far away. All that matters is the operating and the self-belief it requires. You live very intensely when you operate. Perhaps I thought that seeing my own brain would confirm the fascination with neuroscience that had led me to become a neurosurgeon in the first place, and that it would fill me with a feeling of the sublime. But it was vanity. I had blithely assumed that the scan would show that I was one of the small number of older people whose brains show little sign of ageing. I can now see that although I had retired, I was still thinking like a doctor – that diseases only happened to patients, that I was still quite clever and had a good memory, with perfect balance and coordination. I ran many miles every week and lifted weights and did press-ups. But when I eventually looked at my brain scan, all this effort looked like King Canute trying to stop the rising tide. I was looking at ageing in action. My 70-year-old brain was shrunken and withered As I looked at the images on my computer’s monitor, one by one, just as I used to look at my patients’ scans, slice by slice, working up from the brain stem to the cerebral hemispheres, I was overwhelmed by a feeling of complete helplessness and despair. I thought of folk stories about people who had premonitions of attending their own funeral. I was looking at ageing in action, in black-and-white MRI pixels, death and dissolution foretold, and already partly achieved. My 70-year-old brain was shrunken and withered, a worn and sad version of what it once must have been. There were also ominous white spots in the white matter, signs of ischaemic damage, small-vessel disease, known in the trade as white matter hyperintensities – there are various names for them. They looked like some evil pox. Not to put too fine a point on it, my brain is starting to rot. I am starting to rot. It is the writing on the wall, a deadline. I have always felt fear as well as awe when looking at the stars at night, although the poor eyesight that comes with age now makes them increasingly difficult to see. Their cold and perfect light, their incomprehensible number and remoteness, the near eternity of their lives, in such contrast to the brevity of mine. Looking at my brain scan brought the same feeling. The urge to avert my eyes was very great. I forced myself to work through the scan’s images, one by one, and have never looked at them again. It is just too frightening. Sign up to our Inside Saturday newsletter for an exclusive behind-the-scenes look at the making of the magazine’s biggest features, as well as a curated list of our weekly highlights. There is extensive medical literature about the white-matter changes on my brain scan, the white matter being the billions of axons – electrical wires – that connect the grey matter, the actual nerve cells. If we reach 80 years old, most of us will have these changes. Their presence is associated with an increased risk of stroke, although it is unclear whether they predict dementia or not. If we make it to 80, we have a one-in-six risk of developing dementia, and the risk gets greater if we live longer. It is true that a so-called “healthy lifestyle” reduces the risk of dementia to a certain extent (some researchers suggest 30%), but however carefully we live, we cannot escape the effects of ageing. We can only delay them, if we are lucky. Long life is not necessarily a good thing. Perhaps we should not seek it too desperately. We accept that wrinkled skin comes with age but find it hard to accept that our inner selves, our brains, are subject to similar changes. These changes are called degenerative in the radiological reports, although all this alarming adjective means is just age-related. For most of us, as we age, our brains shrink steadily, and if we live long enough, they end up resembling shrivelled walnuts, floating in a sea of cerebrospinal fluid, confined within our skull. And yet we usually still feel that we are our true selves, albeit diminished, slow and forgetful. The problem is that our true self, our brain, has changed, and as we have changed with our brains, we have no way of knowing that we have changed. It is the old philosophical problem – when I wake in the morning, how can I be certain I am the same person today that I was yesterday? And as for 10 years ago? Hope is one of the most precious drugs doctors have at their disposal I always downplayed the extent of these age-related changes seen on brain scans when talking to my patients, just as I never spelled it out that, with some operations, you must remove part of the brain. We are all so suggestible that doctors must choose their words very carefully. It is easy for doctors to forget how patients cling to every word, every nuance, of what we say. You can unwittingly precipitate all manner of psychosomatic symptoms and anxieties. I usually told cheerful white lies. “Your brain looks very good for your age,” I would say, to the patients’ delight, irrespective of what the scans showed, provided that they showed only age-related changes and nothing more sinister. The patients would leave the room smiling happily and feeling much better. The eminent American cardiologist Bernard Lown has written of how important it can be to lie to patients – or at least to be much more optimistic than the facts perhaps justify. He tells stories of patients of his who were close to death from heart failure but who rallied and survived when he was overly positive. Hope is one of the most precious drugs doctors have at their disposal. Even if there’s only a 5% chance of survival, a good doctor will emphasise that 5% of hope without denying or hiding the 95% chance of death. It is Pandora’s box – however many horrors and ailments come out of the box, there is always hope. Only at the very end does hope finally flicker out. Hope is not a question of statistical probability or utility. Hope is a state of mind, and states of mind are physical states in our brains, and our brains are intimately connected to our bodies (and especially to our hearts). Indeed, the idea of a disembodied brain, promoted by the more extreme protagonists for artificial intelligence, might well be meaningless. This is not to say that being kind and hopeful will cure cancer or enable us to live for ever. The human mind is always trying to reduce all events to single causes, but most diseases are the product of many different influences, and the presence or absence of hope is only one among many. I should have known that I might not like what my brain scan showed, just as I should have known that the symptoms of prostatism that were increasingly bothering me were just as likely to be caused by cancer as by the benign prostatic enlargement that happens in most men as they age. But I continued to think that illness happened to patients and not to doctors, even though I was now retired. Twenty months after I had my brain scanned, I was diagnosed with advanced prostate cancer. I had had typical symptoms for years, steadily getting worse, but it took me a long time before I could bring myself to ask for help. I thought I was being stoical when in reality I was being a coward. I simply couldn’t believe the diagnosis at first, so deeply ingrained was my denial. I had been planning on seeing a medical colleague about my increasingly irritating prostatic symptoms – poor flow, and urgency and frequency of urination – but the lockdown put this on hold. Besides, the pandemic was such a strange and intense experience that I quite forgot my symptoms and another seven months passed before I arranged an appointment. To save time, I decided to go privately, although I no longer had private medical insurance. Having carefully washed my bottom, in anticipation of a rectal examination, I cycled into Harley Street, swigging a litre of mineral water as I went. I had been told to do this so that I could have my urine flow measured on arrival. I had to report to a friendly nurse who made me drink many more cups of water. She would put her head round the door every so often. “Are you bursting yet?” she would ask. Henry Marsh, at home in Oxford. Photograph: Sebastian Nevols/The Guardian When I eventually reached this point, I was directed to a urinal that carried out the necessary measurements and recorded my sad and struggling attempt to empty my bladder – a problem I had been living with for many months, perhaps even years. Once this was done, I was ushered up a grand carpeted staircase to the consulting room. The double oak doors of the room were so tall and imposing that I hesitated to go in, finding it hard to believe they were simply for a medical consulting room. But this was Harley Street, and not the NHS. The room was huge, and my colleague, Ken, masked like myself for the pandemic, was sitting behind an enormous desk. It reminded me of stories of Mussolini, who had a gigantic desk in his office. His cabinet ministers had to run at the double the long distance to his desk when they came to deliver their reports. But Ken is a very nice man and not at all like Mussolini. He had operated on me two years ago for a kidney stone – I had made careful inquiries as to whom I should consult. Being able to do this is probably the greatest benefit of being a doctor yourself. It is otherwise less clear that being a doctor is helpful when you are ill. In my case, it proved to be little short of disastrous. We chatted for a while. The Covid crisis had been good for him, he said – his NHS hospital had come to understand that stones, as he put it, were important. Patients continued to need urgent treatment for kidney stones during the lockdown, unlike some other specialties. We discussed my symptoms – I found myself playing them down, or at least my endless preoccupation with them. “I need to examine you,” he said a little apologetically. In the past I had always rather dreaded having a rectal examination – in practice, it is unremarkable. “Your prostate is a little firm,” he said as I pulled my trousers up. “I don’t want a PSA,” I said. PSA stands for prostate-specific antigen, and is an abbreviation with which many ageing men are deeply concerned. The test measures a protein in the blood that is secreted specifically by the prostate gland. The prostate steadily enlarges in most men throughout their life, and in one in seven men turns cancerous. In these cases, the PSA will rise, although cancer is not the only cause of a raised PSA, and a slightly raised level in an older man can be perfectly normal. For many men, the cancer is relatively harmless – they die with it rather than from it, with few ill effects. This can make it difficult to decide whether to treat the cancer in every case or not – as no treatment is without some risk. The cancerous gland can be removed with surgery, provided it has not spread beyond the gland’s capsule, but the operation comes with the risk of impotence and incontinence, and it can be hard to know when the risk of surgery is justified. But if the gland has spread beyond the prostate, it will probably kill the man – although this might take some years. I am amazed at how wilfully blind I was, how I had been so frightened by my symptoms that I had now probably left it too late Ken managed to persuade me to have a PSA test. I couldn’t very well deny that I had come to seek his advice. “If it is cancer, I don’t want any treatment,” I told him, “unless it progresses. ” “I know where you’re coming from, but it’s no good putting your head in the sand,” he said. Looking back, I am amazed at how wilfully blind I was – how I had been so frightened by my symptoms over the years that I had refused to admit the need for a PSA, and had now probably left it too late. “You know,” I said, as I was about to leave, “when I was still in practice, all I ever wanted to do was operate all the time. It meant more to me than anything else, although I also loved caring for patients. But now that I have finished, I don’t miss it at all – I’m not entirely sure why not. Do you like honey?” He replied that he did, and that he had honey every morning for breakfast, so I pulled out the small pot of honey made by the bees I keep in my garden and gave it to him. I had had intermittent prostatic symptoms for close on 25 years, which at first were almost certainly due to a common condition called chronic prostatitis. I was a little embarrassed by them, and did not seek professional help, and also as a doctor I suffered from the firm conviction that illness happened to patients and not to doctors such as myself. When we are medical students we enter a new world – a world of illness and death. We learn about all manner of frightening diseases, and how they usually start with trivial symptoms. Many students, in response to a few minor aches and pains, become convinced that they have developed a catastrophic illness. In order to survive, they have to believe that diseases only happen to patients and not to themselves. A few doctors remain hopeless hypochondriacs throughout their careers, but most of us carefully maintain a self-protective wall around ourselves, which separates us from our patients, and becomes deeply ingrained, sometimes with unfortunate results. Doctors with cancer are often said to present with advanced disease, having dismissed and rationalised away the early symptoms for far too long. I was well aware of this phenomenon, but this knowledge did not prevent me from falling victim to it myself. Prostatism affects most older men – in medical language, frequency and urgency of micturition , and poor flow. In medical school, students are taught a process cal