Sunday 16 June 2019

Dementia: The bad news... and the good

A third of all cases of dementia can be prevented
A third of all cases of dementia can be prevented

Every three seconds, across the world, there is a new case of dementia. Ten million people are stricken with this brain-destroying disease each year and the number is growing steadily.

The amazing modern-day successes in boosting physical health and life expectancy has caused another challenge - hundreds of millions of people whose life span has increased but whose brain span has not.

The cost of caring for people with dementia exceeds the cost of treating cancer, stroke and heart disease combined - and many health systems are already at breaking point because of this.

Ireland is a relatively young country but, even so, more than 50,000 people have dementia here and we all know how stretched our health system is.

But consider this: By 2046, because of the increased number of older people in Ireland, the number of people with dementia will triple to more than 150,000. If you think the problems in our hospital emergency departments are bad now, wait to see what happens in 2046.

And here is the salt for the wound: the rise in dementia rates is going to be fastest in those low and middle income countries which can least afford to deal with it. The highest impact will be in Africa and Latin America - a perverse, unintended consequence of the remarkable progress that has been made in curing infectious diseases and raising life expectancy dramatically in these regions.

The estimated worldwide cost of dementia in 2018 is one trillion US dollars, and this will rise in 2030 - just 12 years from now - to two trillion dollars.

This is a bleak picture, except for one redeeming fact - perhaps the most important discovery in neuroscience in the last 40 years - the neuroplasticity of our brains.

The adaptable brain

Neuroplasticity means the capacity of our brains to be physically changed and shaped by what we think, feel and do.

When I was a student, I learned that after a few short years of early childhood when the brain was shaped by experience, its connections hardened into a lifelong permanent state - 'hard-wired' was the term - where the only trajectory was a steady decline in, and irreversible death of, its cells and connections over the lifespan.

Then, suddenly, in the 1980s I learned that this was quite wrong - that, in fact, at every age the brain's connections are being constantly moulded, shaped and grown by what people do with their brains. What's more, there is now evidence that in some parts of the brain, new brain cells can grow depending on how the brain is used.

Suddenly, a fact that had puzzled doctors for decades could be explained. This puzzle was that the more education you have in your life, the less likely you are to be diagnosed with dementia later in life. How could something like education affect a disease of the brain?

Neuroplasticity was part of the answer - education physically shapes and builds brain connections and it also tends to keep people using and challenging their brains throughout their lives. This constant challenging and stimulation of the brain builds a stronger, better-connected brain that can keep functioning for longer, even when there is some disease present in the brain.

'Use it or Lose it', then, is a fact, not a myth. We know this is true about our physical health, hence the hordes of middle-aged cyclists in all their Lycra glory of a Sunday morning. But it is only recently that we are becoming aware of the fact that, if we want our brain health to keep up with our body health, we have to give our brains the right levels of challenge and training too.

Education is not the only thing that builds what has been called "cognitive reserve" - that bank balance for the brain that offers some (but not complete) protection against dementia.

Strong social networks are wonderful stimuli for the brain, and keeping stress levels within reasonable limits also helps build a stronger brain.

Hearing difficulties can reduce the stimulation that our brains get, so it is important to make sure we don't gradually get cut off from life's demands by poor hearing.

Physical exercise is also a source of brain-building natural hormones and chemical messengers, and a good diet, rich in oily fish and fresh fruit, vegetables and nuts, doesn't just feed your body - it also grows your brain.

Unfortunately, we can take all these steps and still develop dementia. We hope that in a few years there may be new effective treatments for different types of dementia. So there is hope, and while we wait for new treatments, we can work to keep our brains stimulated even after we have been diagnosed with dementia, because neuroplasticity exists whatever the age and whatever the illness.

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