Use it or lose it: The synaptic pruning effect


Kevin Mangelschots

It’s a well-known fact that abilities we don’t use tend to deteriorate after a while since they operate on the “use it or lose it” principle.

But why is it that we need to use these hard-acquired skills to keep them?

Meet the synaptic pruning effect that gets rid of unused excess synapses.

Let me explain what it is, why it occurs, and how we can prevent this natural process from taking place.

What is the use it or lose it principle?

A person holding a question mark in front of their face.
The use it or lose it principle refers to the fact that you must practice a function or skill regularly if you wish to sustain your competency over those abilities and utilities. Each time we use those functions or that skill set, a specific set of nerve pathways in the central nervous system (the brain and spinal cord) get activated.
If we do not use a specific area of our muscles or brain for an extended period, then the use of that muscle or neural structure will start to get lost.
Yet, every brain function that gets lost is not unrecoverable, as was previously thought. Modern research has shown that brain plasticity allows us to retrieve lost skills, and even prevent degeneration by stimulating our brain appropriately.
This is true concerning muscle building and the skills we’ve developed, but it also holds for our brain and its utilities.

What does, “use it or lose it” mean?

Use it or lose it means you have to apply and drill your skills and functions, or you will end up losing those abilities.
For instance, you need to keep using the boxing skills you’ve acquired over the years, or they will inevitably start to deteriorate. If you don’t exercise, then you will end up in worse shape than you were before.
It operates on the use it or lose it principle.

What is synaptic pruning?

Image depicting how neural pruning happens.

Synaptic pruning, also called neural pruning, refers to a naturally occurring biological process in our brains starting in early childhood until well into adulthood.

When synaptic brain pruning occurs, the brain eliminates redundant synapses.

Synapses are brain structures that enable the neurons to transmit a chemical or electrical signal to other nerve cells.

Our pruning brain functions on this use it or lose it principle. Thus, the skills we don’t use tend to get lost, or at the very least decrease in performance.

Why does synaptic pruning occur?

The word “why” written multiple times on a blue background with question marks surrounding it.

The pruning effect is seemingly disadvantageous for our individual and species’ survival chances.

Yet, our body is an efficient, well-oiled machine, and it rarely does something for no reason. Almost everything we do during our lifespan is aimed at increasing our own and our species’ chance of survival.

The leading theory why researchers think brain pruning occurs is because the maintenance of synapses consumes a lot of nutrients, which may be needed at other places when we mature sexually and when we are still growing.

To summarize, it is generally assumed that this effect happens to prevent using up unreasonable amounts of vital resources that might be more useful at other places in the body to increase our odds of survival.

When does synaptic pruning occur?

Synaptic pruning typically occurs very quickly between the age of 2-10. About 50% of the excess synapses get destroyed during this time.
Nevertheless, it is thought that neural pruning continues until our late 20s.

What happens if synaptic pruning fails?

If synaptic pruning fails, it can lead to a variety of neurological and neuropsychiatric disorders, such as depression and schizophrenia.

It will also cause the brain activity to become less efficient. The brain activity might get blocked by the excess synapses if the pruning process doesn’t happen or fails.

How can we prevent synaptic pruning from happening?

The words “use it or lose it” written in white on a blue background

Neural pruning is a naturally occurring process. But there is one simple thing we can do to stave off synaptic pruning. Using our skills we don’t want to lose.

The best way to prevent it from happening and consequently deteriorating our abilities is using these skills since our brain operates on the “use it or lose it” principle.

When certain abilities aren’t used for a prolonged period, the brain starts deeming those skills and the neurological pathways of these skills as “unnecessary and not needed for survival.” Thus, brain pruning starts happening at those unused regions in the brain to prevent spending any unnecessary energy and resources.

This isn’t just the case with practical abilities like walking, riding a bicycle, or driving a car, … either, but it’s also the case with mental skills like memory, concentration, and problem-solving behavior, …

So in short, the skills you don’t want to lose, you better use frequently to keep them in tip-top shape.

Synaptic pruning example

Image of the word “example” being written with a blue marker by someone's hand.

An example of synaptic pruning happening in the real world is learning a new language in school, but not speaking that same language again for 10–20 years.

Those brain connections have likely been pruned by now, which means you don’t know how to speak that language anymore since you forgot most of the words.


The synaptic pruning effect is a natural process that can only be halted by the use it or lose it principle.

From a biological standpoint, it makes sense because we needed to use our scarce resources efficiently to survive in more ancient times.

To conclude, you need to use the skills that you want to keep. This means that slacking off is not an option!