Forgetting things is good for your brain

Lost glasses and car keys, and can’t remember names? Don’t worry – these can be the signs of a healthy mind. Jenny Tucker explains

One of the most challenging things about getting older is not being able to remember the name of your cat. You look at her and know it’s your beloved pet of eight years but in that moment you haven’t a clue what she’s called. It comes back to you seconds later but it’s frustrating and scary. Yet according to the latest research and expert opinion, this is a perfectly normal state of affairs. Cognitive scientists believe that forgetting is a key part of how our brain works and a healthy and necessary function.

The experience of “natural forgetting’” (like the name of your cat or where you put your car keys) happens to all, and can become more frequent as we age because, like the rest of the body, our senior selves do not always function as efficiently. But unless there is something more serious going on – like dementia or trauma after a head injury – scrabbling around for the whereabouts of your wallet is all part of living in a busy and complex world.

The human brain has to deal with a lot. Information hits us continuously and we must work extra hard to focus on the matter at hand. It’s no surprise we can’t remember it all.

How your memory works

Dr Tomas Ryan is an associate professor at Trinity College Dublin specialising in neuroscience. He has been studying memory for 18 years and is particularly interested in how individual memories are stored in the brain. He says: “New studies indicate there is more to it because memories have a priority order. They remain ingrained in the brain, but at a specific time, other memories take over. So, when you want to remember a particular thing, the brain might pull up something else. You believe you’ve forgotten it but it’s there, just hidden in the background.”

Recent research by Dr Ryan’s team at Trinity focused on the engram cells (memory cells) of lab mice. The animals were given drugs to cause memory loss, but when the engram cells were stimulated, the memory returned – even in mice that had genetic forms of Alzheimer’s disease. This showed that the memory remained in their brain but was locked in. It strongly suggests that memories don’t have an expiry date and can be permanent. So when we think we are forgetting, it is more likely the brain is going through this process of differential remembering.

How memory works is complicated and there is still so much that neurologists don’t know. There are billions of neurons in our brain and most experts agree memory function is carried out by the hippocampus in the temporal lobe. The prefrontal cortex also plays a role in determining what is retained and what gets lost. The book Why We Remember: The Science of Memory and How It Shapes Us by Dr Charan Ranganath explores the fact that forgetting is OK. Ranganath says: “Rather than fighting the selectivity of memory in a futile attempt to remember more, we can embrace that we are designed to forget and use intention to guide our attention so we can remember what matters.”

Ranganath goes on to explain that the human brain is not a memorisation machine, it is a thinking machine; it helps us make sense of the world we live in. “It is designed for economy and to rapidly deploy memories to make sense of the present and focus on the future. To accomplish these goals, we can’t haul around memories for every moment of our lives. If someone were to ask me what constitutes a highly capable memory, I would say it’s being able to access the information that is important to us and to recall life events that are meaningful in some way. There are certain people who have so-called photographic memory, and they are usually experts in a particular area, like chess grandmasters or professional basketball players, with the ability to generate vivid, detailed memories relevant to their expertise. But to my knowledge, no one has ever been reported to have a comprehensive photographic memory for everything. And to be honest, I wouldn’t wish that upon anyone.”

It’s likely that, given the opportunity, most of us would choose to have a ‘better’ memory. But Rangathan encourages us to keep a perspective. He says we all struggle with memory at some point and there is a big difference between this and more degenerative memory loss. “Most of the time it isn’t a memory problem, it’s what I would call a retrieval failure. This means we are unable to pull up information when we need it. Sometimes we need the right cue to find it; sometimes it can’t be found because memories compete with each other. People who have more serious memory disorders often struggle to lay down new memories. Instead of failing to remember the name of someone they just met, they might fail to recall they ever met that person. On average, people with typical memories find it easier to remember recent events than events from long ago, but people with memory disorders have the opposite problem.”

And while Ranganath acknowledges that some types of memory can decline with age – notably ‘episodic memory’, the ability to remember an event – there are super-agers who have a sharp memory well into their latter years.

Stop worrying!

The message in Ranganath’s book is clear. Stop worrying about what you can’t remember and focus on the here and now. “Life is short,” he states. “The transient nature of memory can make life seem much shorter. We tend to think of memory as something that allows us to hold onto the past, when in fact the human brain was designed to be more simply an archive of our experiences. Forgetting isn’t a failure of memory; it’s a consequence of processes that allow our brains to prioritise information that helps us navigate and make sense of the world.

“We can play an active role in managing forgetting by making mindful choices in the present in order to curate a rich set of memories to take with us into the future.”