We are in the middle of the greatest revolution the biomedical sciences have ever seen. Within the next few decades we will see a shift away from the one-size-fits all approach to medicine towards an age of personalized medicine and precision therapies that will allow us to live much longer and healthier lives.
But, what we might be creating by adding years of life is living prisons for dying minds. The afflictions of the body are low hanging fruit compared to the complexity inherent to the brain and what it would take to treat it. As science continues to take bold leaps forward, it may soon leave us with an epidemic of rotting brains in healthy bodies.
Once you turn about twenty, for reasons we can’t properly explain, neurons in your brain start to die. Unlike other cells in your body, neurons don’t grow back. But there are a hundred million neurons in your head with one hundred trillion connections between them, so you don’t notice when a few go.
But over time that damage accumulates. For some it happens faster than others. When damage crosses a certain threshold that death becomes visible as things in the body start going wrong, we call these things symptoms of disease. For example, once 50-80% of the dopamine producing neurons in an area of the brain called the substantia nigra die, people start to experience the tremor and rigidity we call Parkinson’s disease.
But it’s not like anything really changes before or after that threshold is crossed, we just give it the name disease because now symptoms of that cell death are visible, but what led to it is usually decades of accumulated degeneration that doesn’t stop.
And it happens to everyone throughout their life, even people who seem healthy accumulate damage in their brain that eventually leads to cognitive decline. As we age the brain also loses some of its plasticity as there are fewer neurons left to form new connections which is why older people have a harder time learning new skills.
Nothing has been proven to stop or even slow neurodegeneration. There are things that speed it up, like genetic mutations, poor nutrition, inactive lifestyles, and exposure to toxins, but nothing to slow or stop it. If we live long enough we will all suffer from neurodegenerative disorders.
Trying to wrap your head around why the brain is such a difficult puzzle can be a little mind numbing. To master it not only would we need a map of the 100 billion neurons that make up each human brain and the 100 trillion connections between them and how those connections change from moment-to-moment, but we would also need a much better understanding of emerging disciplines like genomics, pharmacogenomics, transcriptomics, and proteomics to name a few.
However there is good news as new techniques are being developed that are giving us a chance to get ahead of neurodegeneration. These ranged from advances in neuromodulation to stem cell research and tissue engineering, to gene therapy. What’s more, the introduction of big data and artificial intelligence will further quicken our stride and get us even closer to understanding our brains, how they develop, how they interact with the world, and all that goes wrong along the way.
But we still have a long way to go as we still don’t understand many of the basic underlying mechanisms that drive neurodegeneration, nor do we have anything yet that can reliably stop it. With incidence of such diseases set to grow rapidly over the next 20 years, we need to refocus our efforts and look critically at the state of brain health and research if we are going to curtail the coming neurodegenerative epidemic.