Dr Roderick Mulgan: Cracking the age code

Illustration: Anna Crichton

Understanding disposition could revolutionise ageing, offering tailored strategies for optimal longevity.

Words: Dr Roderick Mulgan 

Science likes categories, so you will be intrigued to learn there is a new way of classifying people beyond height and star sign. There are different ways to age. Getting worn out is one of the modern world’s biggest concerns, which, it turns out, doesn’t happen the same way for everyone. If you can work out which cohort you belong to, your efforts at fending off the inevitable for as long as possible can be much better focused.

The difference between us as the decades pass is which bit ages fastest. It is like the observation that a chain is as strong as its weakest link. The bit of your physiology that fails first is the bit that should be getting the most remedial attention, and the key takeaway is that it isn’t the same for everyone.

There is a deep well of ageing theory for anyone looking — shortened telomeres, sluggish cell repair, clapped-out mitochondria — but they all treat your organs as one amorphous lump. Which they aren’t.

Your brain might be older than your heart or your liver younger than your kidneys. Hence, the people who can stride up hills well into their 70s or the ones who lose their memory tragically early, and multiple other variations on the theme.The insight is a significant new take on the age-old question of how we come to fall apart, and it has a neologism: “ageotype”. We all have one, and they are not identical. The word was coined by a research group at Stanford University led by Professor Michael Snyder, who laid it all out in a seminal paper in 2020.1 Ageing research has been buzzing
about the theory ever since.

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Professor Snyder’s researchers spent four years following a group of healthy people whose ages ranged from 29 to 75 and bombarding them with investigations. Every iteration of blood constituents, gut bugs and gene samples was probed every three months until more than 18 million data points were in the bag. When the numbers were crunched, a pattern of unexpected elegance emerged: not only do people age differently, which isn’t too much of a surprise, but there were four distinct categories, at least this time round. So, thanks to Professor Snyder, you can now age primarily via your kidneys, liver, immune system or general metabolism. It also seems plausible there are ageotypes for hearts and nervous systems, too, but the data — this is a new idea — didn’t pin them down.

Your metabolism means all the chemical reactions that keep you going, particularly the ones that burn food and turn it into energy. Yes, I mean burn. As a barbecue does with charcoal briquettes, your cells release energy by joining oxygen atoms to organic molecules (food). An ageing metabolism manifests as excess weight and diabetes.

Your immune system is the collection of white blood cells and antibodies that fights off the thorns and viruses that breach your borders. It is also behind the magic of new pink tissue and tendrils of sprouting blood vessels that appear inside a cut and seal it like new. An ageing immune system forgets what the enemy looks like and starts attacking healthy bits of you.

That means rheumatoid arthritis and cancer. Your liver is a multi-tasker that manages nutrients and breaks down toxins. It is your major reservoir of iron and vitamin A, and the first organ blood enters after it leaves your intestine.

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Anything suitable to nourish your tissues, and anything pernicious that shouldn’t get anywhere near them, gets sorted out by the intense scrutiny liver cells bring to bear. A liver that isn’t performing accumulates fat and mismanages multiple vital sorting and detoxifying tasks.

Your kidneys are the other primary conduit for removing toxins, but they also balance your electrolytes and body fluids. When they go wrong, blood pressure goes too high, electrolytes get out of whack, and fluid accumulates. We all have these ageing processes to some extent, but new thinking is that different ones dominate in different people.

The reasons why are not obvious. Sometimes, there is a direct correlation with lifestyle — alcohol and a poisoned liver are pretty obvious — but otherwise, absent some unhealthy habit, your ageotype is just your disposition. Professor Snyder suggests that if we don’t age uniformly, then good health e orts should be individualised. Metabolic agers should emphasise healthy weight and closely monitor blood glucose.

Immune agers need to emphasise a diverse array of coloured plants in their diet, including spices, as there are multiple natural anti-inflammatories to be found therein. e professor also advocates turmeric, one of the plant world’s stand-out anti-inflammatory substances.

Liver agers need to avoid toxins, meaning alcohol. Kidney agers need to make a point of staying hydrated. Brain agers need to maintain cognitive muscles by doing crosswords, playing an instrument, and focusing on new skills. It is never too late to learn one.

Unfortunately, the means for diagnosing these issues in detail remains the preserve of research laboratories, at least for now. Blood work from your doctor can seek markers of kidney and liver function, but these are too basic to detect things going wrong at an early and easily preventable stage — likewise, markers for inflammation. There is, however, a marker for glucose control, and it is straightforward to have your blood pressure done.

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If the ageotype theory continues to intrigue, then new and better methods for making diagnoses are likely to follow. In five or 10 years, your doctor may be much better placed to advise precisely where you stand in the possibilities. It also seems likely that new organs will be brought into the system. There are 78 organs in your makeup if you get down to details like the larynx and pituitary gland, but it is unlikely they will all wind up with a genotype category. However, the clues in the key research that brain age is a distinct category seem likely to be confirmed as new findings roll in. Hearts also seem obvious candidates.

I would put money on bones. Crumbly skeletons are known to afflict some older people, particularly smokers, women and those of slender build. And bowels. Your bowel harbours an elaborate ecosystem of bacteria that manipulate your health in various ways, and the possibility that the correct bugs fend off ageing is being taken seriously.

So give thought to what ageotype you might be. It won’t save your life but it might extend it.

NZ Life and Leisure This article first appeared in NZ Life & Leisure Magazine.

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