Is age the best indicator for emotional and cognitive brain development?

Strict age deadlines for developmental milestones can cause unnecessary stress for both parents and children.

The use of broad age ranges to outline when certain developmental stages usually occur are a useful tool for early detection of learning difficulties and disorders. 

What’s going on in the brain?

Brain development is a complex process that begins before birth. Almost all of the major structures in the brain and the majority of it’s the neurons (brain cells) are formed while a person is still in utero.

The processes that occur after birth build up from these structures, creating links and pathways between different parts of the brain. One of the most important ways these connections are created is through synapses, which are specialised junctions used to transmit signals between cells. The build-up of synapses in the brain allows for different behaviours and actions to be learnt and retained.

"If you think about the brain as a house, all the major structures are formed first, and this is what is happening in utero. What happens next is the interior of the house needs to get developed. Lots of different pathways around the house are built, and these represents white matter in the brain which is developed through both myelination and synaptic development. These connections are created in abundance, so what needs to then happen is the relevant ones need to be differentiated from the irrelevant; the signal needs to be separated from the noise," says Professor Suncica Lah,  Professor of Clinical Neuropsychology.

As a child grows and interacts with the outside world synapses are being created constantly, in fact there are more synapses created than the child will actually need. So while the brain is in the process of creating and strengthening relevant synapses a process called pruning is also occurring. This is where brain cells called microglia differentiate and reject the irrelevant and unused synapses, so that the brain can work as efficiently as possible.

The combination of all these different processes happening in parallel with one another allows a child to go from being unable to hold their own head up to crawling and walking by themselves.


The developmental processes that are occurring in a child’s brain happen in part as a result of the natural maturation of the brain however a large proportion of this growth and development is the result of their interaction with the outside world.

Many of the actions and behaviours that are often thought of as implicit are in fact still learned practices. If a child is kept in a high chair or strapped in a cot all the time and is not provided the opportunity to learn to walk and crawl then they won’t learn those behaviours.

It has been shown that excessive stimulation of a child doesn’t necessarily result in them achieving certain milestones faster; holding a child up to practice walking doesn’t necessarily mean they will learn to walk faster. However, if a child is not given the opportunities to learn these skills then they are at a higher risk of developing a learning difficulty.

It is not possible to give exact age markers for emotional and cognitive development as the process and speed of development differs greatly from child to child and is heavily dependent on their genetics and external stimuli. While, most children learn to crawl before they walk it is not uncommon for a child to learn to skip the crawling step and go straight to walking, development is a fairly individualised process.

What to keep in mind

Being aware of the age ranges where certain developmental milestone usually occur is useful in the early detection of learning difficulties and disorders. It’s important to remember that even if a child is delayed in learning one certain thing this does not necessarily mean that it’s a serious or long term difficulty.

There isn’t always a need to identify a child with a specific diagnosed disorder. This can often lead to delay and an over-focus on the consequences of receiving a diagnosis. What is often more important is identifying developmental needs for the child and family that then allow for targeted supports in specific developmental domains to provide appropriate intervention
Professor Adam Guastella, Michael Crouch Chair in Child and Youth Mental Health

If a child is does seem to be experiencing a learning delay then taking them to see a professional is important so that the cause of this delay can be understood and actions to support and amend can be put in place. 

Find out more about our research and clinical trials.

If you put a child in a black room with no light for 6 years, they’ll be blind and they won’t be able to recover their vision ever again, even if they are removed from the black room. This is because if a pathway in the brain isn’t used, it is lost. This makes early intervention very important as certain skills and pathways need to be practiced to be retained.
Professor Russell Dale, Professor of Paediatric Neurology