No, age doesn’t eat into your memory

Age is often cast as a bit of a villain – one that will invariably steal not only our memories but our entire identity. Well, that’s the fear at any rate. But it’s not the case. The majority of older people (65+ according to the WHO) retain basic cognitive functions until at least 80 and often longer.

We may well become slower, less mentally agile and less able to learn new things, but these are not signs of dementia or that we are losing everything we ever learned or experienced.

In fact, there’s quite a lot we can do to increase the chances of keeping our memory sharp as we grow older. Neurological researchers are in the process of defining what needs to be done and have even discovered that older brains can do things younger ones can’t.

Important to distinguish between old age and illness

For many years, it was widely believed that age and dementia were inseparable. As we age, we lose brain cells, and memories fade – or so the logic went – but recent research shows something else. Age-related changes in a healthy brain look different from those caused by dementia, which is an illness.

Professor Steen Hasselbalch, expert in cognitive neurology and dementia, knows more than most about what happens inside the brain as we grow older and become more prone to illness.

We meet him on Inge Lehmanns Vej in his office in the Danish Dementia Research Centre, part of Rigshospitalet, one rainy Friday. The street is named after the seismologist Inge Lehmann, who was famous for her research into the core of the Earth. The Centre’s focus is on the core of the brain.

Hasselbalch is used to pulling up scans of brain tissue on his screen and can tell whether they show signs of illness or ‘just’ old age.

One of the things he looks for is atrophy – i.e. brain cells that have wasted away. Atrophy is normal in healthy older people, but if cells waste away in particular parts of the brain – at the back or around the seahorse-shaped structure called the hippocampus – it may be due to the most common form of dementia: Alzheimer’s. Another tell-tale sign is the accumulation of proteins in and around the neurons, the brain’s nerve cells.

‘It’s important to distinguish between dementia and ordinary changes such as normal memory loss, which happens to us all due to age,’ says Hasselbalch.

Although dementia is incurable, the symptoms can be managed, and support provided to help patients cope with the challenges of daily life. And now, for the first time, a drug has been authorised in the US that slows dementia down. It could turn out to be a game-changer.

In Denmark, we have 7–8,000 new cases of dementia every year – a number that is not going up despite the number of older people increasing. In fact, the proportion of the population with dementia has fallen throughout the Western world in recent years, probably due to advances in the treatment of vascular disease.

The brain shrinks

What happens to a healthy brain when age makes its mark?

Despite brains being very different and ageing differently, some physiological processes are universal. Over time, the brain shrinks, more neurons waste away, fewer new ones replace them, and fewer new connections are formed between neurons. Hasselbalch describes this as ‘attrition’. It occurs all over the brain, but here are a few specific examples:

Fewer neurotransmitters, which travel back and forth between the neurons, are produced, leading to poorer communication.

The finely meshed network of blood vessels that provide oxygen and carbohydrates shrinks.

Brains cell DNA is damaged, and repair mechanisms impaired. This affects the cells’ ‘energy factories’, the mitochondria, so less energy is generated.

Waste that would otherwise be flushed away while we sleep piles up in the brain, like rubbish in the streets during a bin strike.

‘When many of the processes that normally cleanse the brain deteriorate, it damages the cells,’ says Hasselbalch.

Looking at the brain scans, the professor can see signs of attrition both in the so-called grey matter (the neurons) and in the white matter (the neurons’ nerve fibres, wrapped in fat). The grey areas thin out in older people, while the white areas remain constant or even increase up to the age of 40–50. After this point, the protective fat around the neural connections begins to fade away, causing brain signals to slow down.

The ‘normal’ ageing process of the brain does not always happen on its own. People often also suffer from illnesses that become more common with age, such as high blood pressure, cardiovascular disease and diabetes, which can affect the blood and oxygen supply and cell renewal or result in inflammation.

Longer periods of illness can also play a role, along with diet, exercise and lifestyle.

‘The older we get, the more we feel the impact of the combination of attrition, illness and lifestyle,’ says Hasselbalch.

 

Cognitive tests show effects of age

While Hasselbalch sees attrition, damage and disease on brain scans, clinical neuropsychologist Kasper Jørgensen observes their real-world consequences for patients.

A colleague of Hasselbalch, Jørgensen is an expert in cognitive testing. We meet him in his office at the Centre, where he shows us how age manifests in cognitive terms.

He takes a piece of paper featuring a black-and-white abstract figure composed of both straight and circular lines, which is used to test visual-spatial memory.

‘First you draw a copy of the figure, then we take it away, and you have to draw it freely from memory. The result says a lot about how you remember.’

The test scores range from 0 to 36 points – zero if you remember nothing. Young people score an average of 23 points, older people 15–16.

Another example is a linguistic memory test. A list of words is recited, and the test subject has to remember as many as possible. On this test, young people average nine errors, older people twice as many. Generally speaking, age does take its toll on the memory then.

‘Whatever the test, there’s an age effect. That much is beyond doubt,’ says Jørgensen.

‘The good news is that there’s a great deal of individual variation. Well-educated people in particular can maintain high levels well into old age, perhaps because they have mentally stimulating jobs – they are constantly exercising their brain.’

At this point, the outlook starts to seem more optimistic because there are things that we actually get better at with age and various steps we can take to counteract attrition.

‘Vocabulary, general knowledge and conceptualisation – we get better at these as we grow older and are good at them right to the end,’ says Jørgensen.

This is reflected in how we deal with situations in our daily lives and at work.

‘Older people are better at complex situations, establishing an overview and understanding what’s important,’ says Jørgensen.

Vocabulary, general knowledge and conceptualisation – we get better at these as we grow older and are good at them right to the end

‘If you’re injured and go to A&E, I’d rather be seen by a 60-year-old consultant than a 25-year-old medical student because the consultant will no doubt have seen something similar before and can tell you instantly what tests and treatment you need.’

And there’s also a bonus that has nothing to do with memory.

‘Studies suggest that we become friendlier with age.’

We might not remember as well, but we become nicer

Some people are particularly well protected against dementia

The great variation Jørgensen describes is due to the demographic average including people with severe dementia at one end of the scale and the group called the ‘super-agers’ at the other.

Super-agers avoid the degenerative effects of age on the brain. Even as they grow older, they maintain their cognitive strength. They are keen to take on new challenges and often have an optimistic and positive approach to the future.

Inge Lehmann herself was probably a super-ager. At any rate, she lived to be 104 and conducted research right to the end.

When a super-ager blows out the candles on their 80th-birthday cake, their memory is as fresh as people 20 or 30 years younger. In particular, they have a strong episodic memory – they recall events in their own lives and can connect them to times and places – a visit to a museum last week, what they had for dinner and so on. That’s why they have attracted the attention of researchers.

Scientists from Harvard University have shown that the hippocampus and other parts of particular importance to memory are larger in super-agers than their peers. The larger these areas, the better the memory. Super-agers also have particularly strong neural networks – just as strong as young adults, in fact.

Among the researchers systematically monitoring and studying super-agers is a team from Northwestern University in Chicago. They have established a research programme and are recruiting super-agers aged 80+ with normal IQs and good scores on a range of cognitive tests.

Only 10% of those who express an interest are admitted to this exclusive club. Every year, they are scanned and asked to take various cognitive tests and trials.

In one trial conducted with a control group, the team found that over 18 months, super-agers did not lose as many brain cells as their peers, nor did they lose them as quickly. The control group lost brain cells at twice the speed.

In another study, they dissected the brains of deceased super-agers and made a remarkable discovery – a distinct biological signature. They found cells that were healthier and larger than in peers with age-commensurate memory, peers with cognitive impairment and people 20–30 years younger.

These “super-cells” were found in an area of the brain called the lateral entorhinal cortex, which plays a crucial role in memory – specifically, it gathers large amounts of sensory and other information and relays it to the hippocampus.

This area is also of particular interest because this is where the earliest signs of Alzheimer’s disease show up. Cells here begin to die up to a decade before symptoms are noticed and the condition diagnosed.

The team made another discovery: The super-agers had only a third of the long-tangled protein threads in the neurons, called Tau tangles, which in healthy people are seen as a sign of the onset of Alzheimer’s and other dementias.

The researchers believe that super-agers are more resistant to dementia than their peers, but also to other factors that can exacerbate age-related breakdown of the brain.

Intensive research into super-agers can result in new knowledge of benefit not only to dementia patients but to all of us because finding out what leads to this level of immunity may help doctors intervene to prevent memory disorders and stave off general decline.

The brain renews throughout our lives

But you don’t have to be a super-ager to give age a run for its money. New discoveries in the last two decades have shown that the brain is more malleable than we thought. Scientists describe the adaptable brain as ‘plastic’.

Among other things, they have discovered that the brain can compensate for damage caused by blood clots. Parts of the brain close to the damaged area can take over, at least to a certain extent. In other words, losing brain cells does not always mean diminished abilities.

Another discovery is that the brain can rejuvenate itself. We do not start out with a fixed number of neurons that waste away over time, as was believed until a few years ago. Rather, the brain forms new nerve cells, neurons and connections throughout our lives. Even old brains can grow – which means the memory can be improved.

Researchers talk about a ‘cognitive reserve’ because it is possible to strengthen and maintain cognitive functions throughout our lives. Hasselbalch finds this intriguing.

‘Despite all the damaging processes and the extent of the damage – even if you have Alzheimer’s – we believe it’s possible to strengthen these networks inside the brain,’ he says.

‘It’s a perspective that people perhaps don’t often think about so much.’

But it is also possible to prevent dementia by intervening earlier. We need to start by treating any illnesses effectively in order to limit the damage they cause to the memory. Next, we have to harness the brain’s plasticity – its inherent capacity for change.

‘Population studies show that three factors can strengthen the networks: physical, cognitive and social activity,’ says Hasselbalch.

But what would he recommend if he could only pick one? He has no hesitation: Exercise.

His cycling gear is hanging to dry over a chair in his office because he takes his bike to work every day, even when the rain is streaming down the glass panes of Rigshospitalet – and with good reason.

A brisk walk, 15 repetitions with heavy dumbbells or a long bike ride several times a week – all of these have observable benefits for the brain.

‘Studies measuring the number of neural connections in people who have started exercising show the networks function better and more of them are formed,’ he explains.

Physical activity produces growth factors that help increase brain connectivity. A study has shown that the hippocampus grows by 2% in older people who exercise daily.

‘The beauty of exercise is that it works on two levels,’ explains Hasselbalch.

‘Physical activity can strengthen networks, which helps the brain withstand attacks, and reduces the risk of damage from factors such as high blood pressure, cholesterol and smoking.’

The importance of exercise in avoiding dementia is also to the fore in a brand-new study by the Danish Dementia Research Centre. It shows that lack of physical activity is potentially the risk factor we can do most to prevent in Denmark.

Other risk factors include social isolation and lack of cognitive stimulation. The study suggests that, at least in principle, eliminating all of the risk factors would prevent up to a third of dementia cases.

‘When we interact with others, we use a lot of different networks in different parts of the brain at the same time. We have to read each other’s signals, listen and contribute to the conversation. And that makes the effect greater,’ Hasselbalch says, Stressing the importance of the social aspect.

Cognitive stimulation can take the form, for example, of learning a new language. The key is to stay curious and keep challenging yourself. To return to Inge Lehmann again: She published her last scientific paper at the age of 99.

So the memory’s deadliest enemy isn’t a fading birth certificate but a life without exercise and sensory, intellectual and emotional stimulation.