SOME years ago, I was allowed into Aberdeen’s mortuary. It’s a place where normally, unless you’re a medic or crime writer, you would hope never to enter. The smell struck me first – the faintly sweet, sickly tang of chemicals I couldn’t begin to name.

The doctor who had brought me disappeared for a few minutes, to return carrying a glass box. Inside, swimming in preservative fluid, was a human brain. This was the gift of a person who had died of Alzheimer’s, and had donated this organ for research being conducted at the university.

It was not a thing of beauty, and yet it was wonderful to behold. In shape it was similar to a roast chicken, in colour more like something from fathoms beneath the sea. Areas were threaded with black, but it was mostly pinkish yellow. I could not take my eyes off it.

For someone to offer this part of themselves to science was rather moving. There’s nothing more private, or central, to our sense of identity; this is what makes us who we are. And yet here it was, for all to see: meaningless for someone like me, but for those working to find a cure for Alzheimer’s, offering as many clues as a gloveless thief in a bank vault.

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It made me think that, when my time comes, if I too am suffering from Alzheimer’s, then I would consider giving my brain to the laboratory. Because, despite fresh hope offered by a new drug this week, I suspect this is a disease that’s going to be with us for many decades to come.

Front page headlines about the licensing of the US drug Aducanumab for use in patients in the early stages of Alzheimer’s has made the world sit up. Although it won’t be available in the UK until next year, if approved, it is the first medicine for this disease since 2003. And, unusually, it is tough on the causes of Alzheimer’s rather than merely tackling the symptoms. Specifically targetting ameloid proteins, whose accumulation increasingly disrupts memory, language and other core mental functions, it seems to wind back the clock, allowing patients’ memories to be restored and strengthened.

If that all sounds too good to be true, of course, then there’s always the worry that it is. Instead of assuming dementia will soon be a thing of the past, should we instead curb our enthusiasm? It might be wise.

For a start, while Alzheimer’s, which is a specific disease of the brain, is one of the leading causes of dementia – accounting for between 60 and 80% of cases – there are many other causes of cognitive decline that fall under the umbrella term dementia. If their origins cannot be traced to ameloid build-up – assuming this is the correct line of attack in the first place – then might they be resistant to this kind of drug?

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Added to which, there are plenty of naysayers about Aducanumab’s efficacy. Trials were halted in 2019 because it did not seem to be working, but when the dosage was increased, clear signs of patient improvement were discerned. Some experts, however, remain to be convinced.

Nevertheless, assuming that Aducanumab is as significant a step as its promoters suggest, then surely its licensing marks a giant leap in the right direction for humankind. If it truly is a massive medical watershed, shouldn’t we be popping champagne corks?

Well, as geographers will tell you, there are many watersheds before a river reaches the sea. And given the complexity and virulence of this disease, and the dismal failure rate of many trials thus far, I doubt that a Nobel prize for finding a definitive cure is yet within anyone’s grasp.

Until the arrival of Covid 19, dementia had assumed the unenviable position as the most dreaded of all ailments. Siddhartha Mukherjee’s magnificent biography of cancer, The Emperor of all Maladies, claims that role for the Big C. But even though it still kills millions, the idea of losing our minds to dementia seems to have become even more alarming in the popular imagination. Perhaps this is because, until now, there has been absolutely no prospect of a remedy on the horizon. To date, there’s been little more than an Elastoplast available for Alzheimer’s.

In the past decade, more than 100 drugs that initially seemed promising have fallen by the wayside. That shows both the urgency with which scientists have been working, and the difficulty of making headway. Meanwhile, people diagnosed with dementia gradually enter a twilight zone in which they slowly fade from sight, becoming a shell of their old selves. It is a devastating illness for the patient and those close to them.

Thanks to the race to find a vaccine for Covid, many of us who couldn’t be trusted to wash a test-tube, let alone perform biochemical cartwheels, now understand a bit more about how medical breakthroughs are made. As the almost simultaneous announcement of several vaccines shows, there are different ways to approach the same problem, each of them effective.

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While Aducanumab is for the moment in the vanguard for Alzheimer’s, it’s a fair bet that others on the same track will not be far behind. Meanwhile, those who think the origins of the disease lie elsewhere will continue their endeavours, hoping to confound their rivals.

Professor Craig Ritchie, of Edinburgh University, referred to Aducanumab as “a new chapter but by no means the end of the story”. That analogy is a good way of managing expectations. You don’t need to wear a lab coat to know that a scourge that has defied some of the world’s finest scientists for decades is unlikely to be vanquished overnight. It’s going to take many more years to get it under control, let alone consign it to history.

In this respect, the decidedly bumpy path of Covid provides a road map of sorts. Almost every day there’s a new complication or variant that requires doctors to think on their feet and adjust their predictions. One of the things the pandemic has taught us is to be grateful for every medical intervention on offer. At the same time, we’ve learned not to believe in miracles.

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