Introduction

The topic about what happens to our brain as it grows older offers a lot of scientific controversy, especially if adult humans are capable of growing new brain cells. The more you learn, the more questions would appear. Scientists still cannot agree upon the actual age our brain is considered “fully mature”.

In the past, studies have suggested that the adult brain is hard-wired and unable to grow new neurons. It was thought that the brain is fully developed in the mid to late teens. This theory was then discarded and new evidence to suggested that development may last until at least age 20. Nowadays, most neuroscientists theorize that brain development likely persists until at least the mid-20s – possibly until the 30s.

When the brain is considered as “fully developed”?

“In most of us, by the age of thirty, the character has set like plaster, and will never soften again.”

As discussed already, experts now avoid talking about precise numbers, as brain development is in fact a subject to individual variation. Despite that, it is strongly suggested that the brain should be fully developed by the age of 25 or around the 30s.

It’s kinda funny that we consider an 18 year old person an adult, while at the same time their brain is not fully developed :)

To be honest, by the age of 18, we are „halfway through” the entire process of developing our brain. In fact, our prefrontal cortex doesn’t have nearly the functional capacity at age 18 as it does at 25. After the age of 25 major changes happen to our brain. Our reward system is most active when we are teenagers. By the age of 25 it gradually drifts back to its normal functioning. This means that 25 year old (or older) adults tend to feel less anxious and be capable to control their impulses, while younger ones would struggle with impulsive decisions and fail to control their behavior to achieve their goals.

What in the hell is the prefrontal cortex and why it’s development is so important ?

As you probably know, when talking about brain areas and their functions, there are no straightforward short answers. The functions which the prefrontal cortex executes are various and even though its development begins during adolescence, scientists suggest that it continues until at least our mid 20s or early 30s.

The prefrontal cortex is responsible for the so called ‘executive functions’ such as:

• Our ability to pay attention: Your ability to focus on one subject, while ignoring others is strictly related to your prefrontal cortex’s development. Usually people who struggle with this ability or suffer from attentional deficits have, could have literally abnormalities in their prefrontal cortex region. Overdosing with particular substances like drugs or alcohol could also physically damage that region, but we will talk more about that later.

• The ability to plan, create abstract ideas and make the right decisions are also functions executed by your prefrontal cortex. Whenever you set a goal, discuss the ways to achieve it and try to find the best decision for it, the prefrontal cortex ‘comes into play’. When this region is not fully developed it could affect your planning capabilities, logical and rational thinking and decision making.
  On the contrary, when it reaches ‘full maturity’, naturally your logical thinking would improve. You would become better at solving problems, making right choices and also be better at controlling your impulsive behavior.

Naturally, it would be easier for you to organize your thoughts and become a better person.

• Short-term or working memory:
  Scientists hypothesize that the peak of our short-term memory is when the prefrontal cortex fully develops (around the age of 25). After that, cognitive decline is observed.

What is cognitive decline?

Whilе thе еxact causе of cognitivе dеclinе is still a mystеry, wе know that it is a natural procеss causеd by thе aging of nеurons and thе dеcrеasеd spееd at which thе brain functions. Vеry fеw population basеd studiеs of cognitivе dеclinе in normal agеing havе usеd sufficiеntly sеnsitivе and broad-ranging tеsts of cognitivе function to еnablе invеstigation of change in different cognitive domains.

Cognitive decline is strongly related to our memory functions. It is important to understand that memory difficulties naturally occur as the brain gets older, and they could happen at any age and under any circumstances. All of us are experiencing memory difficulties on daily basis: remembering the name of a person you met some time ago; where you left your keys etc. Sometimes these difficulties could occur because of depression, anxiety or stress.

On the other side, actions which become automatic like riding a bike, driving a car or swimming, along with cultural knowledge remain intact. The problem begins when a person fails to remember these automatic actions and this disrupts their everyday life.

Such systematical forgetting could lead to incapability to lead a normal life and usually in such situations the person should contact a doctor. In this case we are talking about Mild cognitive impairment. It is important to understand that cognitive decline is not the same as Mild cognitive impаirment аnd does not result in the loss of neurons but rаther chаnges in neurotrаnsmission thаt аffect brаin functioning.

What is mild cognitive impairment?

As I already mentioned, mild cognitive impairment involves cognitive decline beyond what we normally expect in a person of the same age with preservation of function.

Some of the symptoms include

• Losing everyday objеcts too oftеn (e.g. keys, phone, wallet)
• Forgеtting to go to еvеnts or appointmеnts (which are actually important)
• Having morе troublе coming up with words than othеr pеoplе of thе samе agе (literally failing to recall them daily)

While this condition could be irritating for the patient, it is important to know that having MCI is not the same as being diagnosed with Alzheimer’s. The personality of the sufferer remains intact. However, being diagnosed with MCI is often the first step before developing Alzheimer’s. Studies suggest that 8 of 10 people diagnosed with MCI develop Alzheimer’s within seven years, while 1 to 3 % of the people older than 65 who have normal cognitive functions develop Alzheimer’s in 1 year.

Probably the next question should be

What can we do to avoid MCI ?

Today we know that our brain is actually not that hardwired as scientists previously thought. In fact, thanks to “the brain's ability to reorganize itself by forming new neural connections throughout life“ or also called neuroplasticity there are high chances for us to literally build our better cognition.

A new study, published in the journal Cell Stem Cell, suggests that healthy older men and women can generate just as many neurons as teenagers.

“We found that older people have similar ability to make thousands of hippocampal new neurons from progenitor cells as younger people do,” said lead author Dr. Maura Boldrini, associate professor of neurobiology at Columbia University.

“We also found equivalent volumes of the hippocampus (a brain structure used for emotion and cognition) across ages. Nevertheless, older individuals had less vascularization and maybe less ability of new neurons to make connections.”

They have examined the brains of 28 previously healthy cadavers aged 14-79 who had died suddenly. This is the first time researchers have analyzed newly formed neurons and the state of blood vessels within the entire human hippocampus soon after death.

This discovery is really promising and it means that each person has equal chances to improve their cognitive abilities if they train their brain.

Train your brain and remain healthy

Today we have a lot of scientific evidence that factors like physical exercise, good nutrition, social connection with others, and mental stimulation all have huge impact on our cognitive abilities.
Еvidеncе suggеsts that dеspitе advancing agе, our brains, and thus our cognitivе functions, rеtain thе ability to bе maintainеd and strеngthеnеd through thе biological procеss of nеuroplasticity.

Our brain is literally changing. Neurons that wire together – fire together. Active and stimulated neurons receive more nutrition and oxygen. Creating and maintaining new neural connections keeps your brain sharp and agile.
Complex mental activity, memory games and exercises are a great and fun way to keep a good shape. The more diverse connections you create, the more ways you develop for your brain to use when it’s time to solve a problem or make a decision.

Scientific sources:

1. Does Cognitive Training Prevent Cognitive Decline?: A Systematic Review.

2. Mapping cortical change across the human life span

3. Handbook of Young and Adulthood

4. Human Hippocampal Neurogenesis Persists throughout Aging

Articles for further information on this topic:

1. What It Takes To Change Your Brain’s Patterns After Age 25

2. 'Brain training' app improves memory in people with cognitive decline

Pictures: Pixabay