Forgetfulness or early dementia? How to decipher your memory loss

Telegraph

a day ago

Illustrations by James Yates
At some point, we've all strode into a room with purpose and proceeded to completely forget what we were about to do. 'It's a very common complaint,' confirms Prof Scott Small, director of the Alzheimer's Disease Research Centre at Columbia University, who has studied memory for more than three decades.
It used to be thought that a forgetful blip like this served no purpose and was simply a malfunction in our memory machinery, but now we know otherwise.
Our memory machinery comprises several stages: our short-term and long-term memory, as well as our ability to save and recall memories.
Prof Small uses the analogy of a computer to explain how we remember and forget: 'If you type something into a document and don't save it, it's gone forever – that's your short-term memory,' he says. 'If you click save, that transfers information from the short-term memory to the long-term memory.
'The other function is to be able to come back to your computer, or brain, and recall what was talked about the day before. For this, you need to have the 'open' function to be able to sift through all your memories and choose the right one.'
Rather than a glitch in this hardwiring, forgetting is a healthy and necessary part of our brain's normal functioning and is vital for our creativity and mental health, as Prof Small explains in his book Forgetting, The New Science of Memory. Not only does forgetting clear cognitive bandwidth and ensure our brains are not overwhelmed with irrelevant information, but 'emotional forgetting' is also necessary to move past traumatic experiences.
Though, there is a catch. As well as normal forgetting, there is also what Prof Small refers to as 'pathological forgetting' – the type that we are right to worry about. Typically caused by neurodegenerative disorders, it indicates a worsening of memory that impacts our ability to live our life fully. 'If you notice worsening of your memory over time from your own baseline, that's probably pathological forgetting, such as Alzheimer's.'
Here, Prof Small shares his expertise on common examples of forgetting to distinguish which fall into the normal category and which could be an early sign of Alzheimer's. 'However, the ultimate diagnosis is when you see a doctor,' he notes.
I've gone upstairs and forgotten why
'That's a super common complaint,' Prof Small says. 'This symptom alone tells me that it's probably the hippocampus, as that's the structure of the brain that's critical for memory.'
The hippocampus is the 'save' button on your computer, transferring information from temporary to long-term.
'If that's always happened to you, it's normal forgetting.' Like height and weight, normal forgetting is a trait that varies between us and it's nothing to worry about if it remains consistent.
However, if you're increasingly catching yourself uncertain about what you're doing mid-task, it could be an early indicator of pathological forgetting, which can be a result of cognitive ageing (forgetting that occurs as part of the normal ageing process) or Alzheimer's, Prof Small says.
'This symptom alone is not enough for me to say whether it's the earliest stages of Alzheimer's or if it's just cognitive ageing,' he notes.
'A rule of thumb in medicine is, if you experience something that really disturbs your life, it might be worth seeing a doctor. But, on its own, forgetting why you've gone upstairs doesn't declare itself as a disorder that's worth seeing a doctor for.'
I'm getting names mixed up
If you've forgotten or mixed up the name of someone you met a couple of times many years ago, it's nothing to worry about, Prof Small says. If you've forgotten the name of a loved one as a one-off, it's also not a cause for concern. 'It may be a bad night's sleep or stress,' he notes.
'But if someone's frequently forgetting the names of loved ones, people in their inner circle, it's time to see a doctor,' he says. It indicates a memory problem and could be a sign of Alzheimer's, he says.
Similarly, if you forget the name of your prime minister or president, that's more concerning than if you forget the name of your local MP, Prof Small says.
I can't remember how to make my favourite recipe
'If someone forgets a recipe that they've been making over and over again, I'm starting to worry about a disease,' Prof Small says. 'It sounds like Alzheimer's.'
The memory decline that occurs with age doesn't affect our memory 'hard drive', where we store key pieces of information that we use regularly, like a favourite recipe.
However, Alzheimer's does. 'It spreads to areas of the memory store, memory retrieval and recall, while ageing does not,' Prof Small says.
'The example of the recipe sounds like Alzheimer's because it's not the 'save' function of our brain,' which is used for new memories, he notes. Instead, it signals a problem with the memory hard drive.
I got lost on a route I've done a million times
Whilst forgetting why you walked into a room or the name of someone you only vaguely know is likely innocuous, Prof Small says that getting lost is a sign of something more serious. 'If someone tells me that they've forgotten where they've parked their car or if they've gotten lost while driving to work, that's a red flag,' he says. 'I start thinking, maybe this is Alzheimer's.'
One way to think about the hippocampus is as a circuit made up of different regions that are all interconnected, Prof Small explains. The area responsible for spatial memory is the region where Alzheimer's takes hold. 'So when I hear people complain about getting lost, I start thinking more about Alzheimer's disease,' he says.
I asked my husband a question but can't remember the answer five minutes later
Forgetting information that we've just been told happens to all of us, Prof Small says. It could be poor attention or, if it's always in relation to your husband, there could be psychological reasons why you're not focusing on what he's saying, he notes.
As a result, this falls into normal forgetting but, if it's becoming more frequent, this could be a worrying symptom.
What can we do to protect our memory?
There are many risk factors that increase the risk of developing Alzheimer's and other forms of dementia, including obesity, poor heart health, high blood pressure and cholesterol and diabetes, Prof Small says. 'That doesn't mean these factors alone will cause Alzheimer's but, if you're going to get it, these may accelerate it,' he explains.
In addition, there are certain genes that are associated with Alzheimer's, most famously Apolipoprotein E (APOE), and a family history also raises the risk. While these can't be changed, living a healthy lifestyle has been shown to benefit brain health and reduce the risk of dementia.
'Exercise seems to be a very strong influencer of maintaining our memory health into late life,' Prof Small notes. Meanwhile, his own research has found that eating a diet rich in flavanols, compounds found in apples, berries and tea, amongst other fruits and vegetables, also protects brain health.
Scientists are also racing to find medicines to ward off memory-robbing diseases. 'Where we are in the field is trying to develop statins for the brain,' Prof Small says.
To do that, researchers need to understand the mechanisms that are causing Alzheimer's, with the brain's immune network and system for moving proteins around our cells (known as the trafficking pathway) under investigation.
So far, development has focused on drugs that work by clearing proteins called amyloid from the brain, which have been shown to disrupt neuron function. However, these have so far been blocked for use on the NHS due to their cost (estimated to be £30,000 per patient per course of treatment) and worries over side effects.
'The next generation of drugs are trying to target either the immune response or the trafficking pathway,' he explains.
'Once the biomedical enterprise has a target, where the field at large is so sophisticated, we should be optimistic that we will have a way to intervene,' Prof Small says.
'It could mean that in a year we'll have effective new drugs that target the pathways that I and others believe will be more beneficial than anti-amyloid drugs. It could take a few years but I don't think it's going to take decades.
'I think we're on the cusp of really translating all the remarkable discoveries that happened in the first 20 years of this century into meaningful therapeutics.'